Last data update: May 30, 2025. (Total: 49382 publications since 2009)
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Estimated Current and Future Congenital Rubella Syndrome Incidence with and Without Rubella Vaccine Introduction - 19 Countries, 2019-2055
Lebo E , Vynnycky E , Alexander JP Jr , Ferrari MJ , Winter AK , Frey K , Papadopoulos T , Grant GB , O'Connor P , Reef SE , Crowcroft NS , Zimmerman LA . MMWR Morb Mortal Wkly Rep 2025 74 (18) 305-311 ![]() Rubella is a leading cause of vaccine-preventable birth defects. Rubella virus infection during early pregnancy can result in miscarriage, fetal death, stillbirth, or a constellation of birth defects known as congenital rubella syndrome (CRS). This report describes current and future estimated CRS incidence in countries that have not yet introduced rubella-containing vaccine (RCV) into their national childhood immunization schedules and the estimated effect of implementing a recent recommendation to introduce RCV into these programs even if population coverage with measles-containing vaccine is <80%. During 2000-2022, the number of countries that introduced RCV increased from 99 (52%) of 191 in 2000 to 175 (90%) of 194 in 2022. By the end of 2023, 19 lower- and middle-income countries had not yet introduced RCV. In 2019, an estimated 24,000 CRS cases occurred in these countries, representing 75% of the estimated 32,000 cases worldwide. In a modeling study estimating the effect of RCV introduction in these countries during 2025-2055, an estimated 1.03 million CRS cases are projected to occur without RCV. In contrast, fewer than 60,000 cases are estimated if RCV is introduced with catch-up and follow-up supplementary immunization activities, averting more than an estimated 986,000 CRS cases over 30 years. Based in part on these estimates, in September 2024, the World Health Organization Strategic Advisory Group of Experts on Immunization recommended removing the ≥80% coverage threshold and instituting universal RCV introduction in these countries. RCV introduction in these 19 countries during 2025-2030 could rapidly accelerate progress toward rubella and CRS elimination worldwide. |
On the path to measles and rubella elimination following rubella-containing vaccine introduction, 2000-2023, Namibia
Masresha BG , Shibeshi ME , de Wee R , Shapumba N , Sayi T , Reef SE , Goodson JL . Vaccines (Basel) 2024 12 (9) INTRODUCTION: The WHO Measles and Rubella Strategic Framework 2021-2030 within the Immunization Agenda 2030 includes both measles and rubella elimination goals and provides guidance to countries for planning and implementing the measles and rubella elimination strategies. Namibia has been implementing measles elimination strategies since 1997. METHODS: We reviewed and described the implementation of measles and rubella elimination strategies and the programmatic and epidemiological situation in Namibia during 2000-2023. Namibia introduced a rubella-containing vaccine (RCV) in 2016 as a combined measles-rubella (MR) vaccine using a MR catch-up campaign, targeting a wide age range based on detailed analysis and triangulation of multiple key data sources including MR vaccination coverage, MR case-based surveillance, detailed measles outbreak investigations, and serosurveys. RESULTS: In 2020, estimated MCV1 coverage in Namibia reached 90% and has been sustained at 91% in 2021 and 2022. MCV2 was introduced in 2016, and the estimated MCV2 coverage has steadily increased to 79% in 2022. Following the MCV2 introduction and the implementation of the wide age range MR catch-up campaign in 2016, annual measles and rubella incidence decreased substantially. During 2017-2023, the period following the implementation of the catch-up MR vaccination SIA in 2016, average annual measles incidence per million population in Namibia decreased by 97% from the average during 2010-2016. Similarly, the average annual rubella incidence decreased by 95% from 2010-2016 to 2017-2023. DISCUSSION: Successful implementation of the 2016 wide age range campaign and maintaining high routine immunization coverage likely led to the significant reduction in measles and rubella incidence in Namibia. To sustain the reduction in measles and rubella incidence and attain the elimination targets, Namibia needs to attain and maintain high routine immunization coverage with both doses of the MR vaccine and implement timely and high-quality periodic MR follow-up SIAs. High-quality elimination-standard measles and rubella surveillance will help guide strategies and serve as the basis for the eventual verification of measles and rubella elimination in Namibia according to the WHO-recommended framework. |
The path to eradication of rubella
Reef SE , Icenogle JP , Plotkin SA . Vaccine 2023 41 (50) 7525-7531 Since 1969, rubella and its harmful effect on fetuses infected in utero can be prevented by rubella vaccine, usually given in combination with measles vaccine. The rubella vaccine is highly protective both in children and in adults including women intending to become pregnant. Owing to the use of combined measles and rubella vaccines, congenital rubella infection has been eliminated from the Western Hemisphere and nearly all of Europe. Such combined vaccination is now being applied throughout the world, posing the possibility of eventual rubella eradication. The existence of viruses of animals related to rubella does not appear to be a barrier to eradication of the human virus. However, persistent rubella virus in infants infected in utero and of immunosuppressed patients with granulomas may pose a problem for eradication. Nevertheless, this review posits that eradication of rubella is now feasible if routine vaccination of infants and surveillance for chronic infection are correctly applied. |
Estimates of the global burden of Congenital Rubella Syndrome, 1996-2019
Vynnycky EPhD , Knapp JKPhD , Papadopoulos TPhD , Cutts Ft Md , Hachiya MPhD , Miyano SPhD , Reef Se Md . Int J Infect Dis 2023 137 149-156 OBJECTIVES: Many countries introduced rubella-containing vaccination (RCV) after 2011, following changes in recommended World Health Organization (WHO) vaccination strategies and external support. We evaluated the impact of these introductions. METHODS: We estimated the country-specific, region-specific and global Congenital Rubella Syndrome (CRS) incidence during 1996-2019 using mathematical modelling, including routine and campaign vaccination coverage and seroprevalence data. RESULTS: In 2019, WHO African and Eastern Mediterranean regions had the highest estimated CRS incidence (64 (95% CI: 24-123) and 27 (95% CI: 4-67) per 100,000 live births respectively), where nearly half of births occur in countries that have introduced RCV. Other regions, where >95% of births occurred in countries which had introduced RCV, had a low estimated CRS incidence (<1 (95% CI: <1-8) and <1 (95% CI: <1-12) per 100,000 live births in South East Asia (SEAR) and the Western Pacific (WPR) respectively, and similarly in Europe and the Americas). The estimated number of CRS births globally declined by approximately two thirds during 2010-2019, from 100,000 (95% CI: 54,000-166,000) to 32,000 (95% CI: 13,000-60,000), representing a 73% reduction since 1996, largely following RCV introductions in WPR and SEAR, where the greatest reductions occurred. CONCLUSIONS: Further reductions can occur by introducing RCV in remaining countries and maintaining high RCV coverage. |
Combining serological and contact data to derive target immunity levels for achieving and maintaining measles elimination (preprint)
Funk S , Knapp JK , Lebo E , Reef SE , Dabbagh AJ , Kretsinger K , Jit M , Edmunds WJ , Strebel PM . bioRxiv 2019 201574 Background Vaccination has reduced the global incidence of measles to the lowest rates in history. However, local interruption of measles virus transmission requires sustained high levels of population immunity that can be challenging to achieve and maintain. The herd immunity threshold for measles is typically stipulated at 90–95%. This figure does not easily translate into age-specific immunity levels required to interrupt transmission. Previous estimates of such levels were based on speculative contact patterns based on historical data from high-income countries. The aim of this study was to determine age-specific immunity levels that would ensure elimination of measles when taking into account empirically observed contact patterns.Methods We combined estimated immunity levels from serological data in 17 countries with studies of age-specific mixing patterns to derive contact-adjusted immunity levels. We then compared these to case data from the 10 years following the seroprevalence studies to establish a contact-adjusted immunity threshold for elimination. We lastly combined a range of hypothetical immunity profiles with contact data from a wide range of socioeconomic and demographic settings to determine whether they would be sufficient for elimination.Results We found that contact-adjusted immunity levels were able to predict whether countries would experience outbreaks in the decade following the serological studies in about 70% of countries. The corresponding threshold level of contact-adjusted immunity was found to be 93%, corresponding to an average basic reproduction number of approximately 14. Testing different scenarios of immunity with this threshold level using contact studies from around the world, we found that 95% immunity would have to be achieved by the age of five and maintained across older age groups to guarantee elimination. This reflects a greater level of immunity required in 5–9 year olds than established previously.Conclusions The immunity levels we found necessary for measles elimination are higher than previous guidance. The importance of achieving high immunity levels in 5–9 year olds presents both a challenge and an opportunity. While such high levels can be difficult to achieve, school entry provides an opportunity to ensure sufficient vaccination coverage. Combined with observations of contact patterns, further national and sub-national serological studies could serve to highlight key gaps in immunity that need to be filled in order to achieve national and regional measles elimination.ESEN2European Sero-Epidemiology Network 2EUROEuropean RegionMCEMisclassification errorWHOWorld Health Organization |
Past as prologue-use of rubella vaccination program lessons to inform COVID-19 vaccination
Dixon MG , Reef SE , Zimmerman LA , Grant GB . Emerg Infect Dis 2022 28 (13) S225-s231 The rapid rollout of vaccines against COVID-19 as a key mitigation strategy to end the global pandemic might be informed by lessons learned from rubella vaccine implementation in response to the global rubella epidemic of 1963-1965. That rubella epidemic led to the development of a rubella vaccine that has been introduced in all but 21 countries worldwide and has led to elimination of rubella in 93 countries. Although widespread introduction and use of rubella vaccines was slower than that for COVID-19 vaccines, the process can provide valuable insights for the continued battle against COVID-19. Experiences from the rubella disease control program highlight the critical and evolving elements of a vaccination program, including clearly delineated goals and strategies, regular data-driven revisions to the program based on disease and vaccine safety surveillance, and evaluations to identify the vaccine most capable of achieving disease control targets. |
Feasibility of measles and rubella vaccination programmes for disease elimination: a modelling study
Winter AK , Lambert B , Klein D , Klepac P , Papadopoulos T , Truelove S , Burgess C , Santos H , Knapp JK , Reef SE , Kayembe LK , Shendale S , Kretsinger K , Lessler J , Vynnycky E , McCarthy K , Ferrari M , Jit M . Lancet Glob Health 2022 10 (10) e1412-e1422 BACKGROUND: Marked reductions in the incidence of measles and rubella have been observed since the widespread use of the measles and rubella vaccines. Although no global goal for measles eradication has been established, all six WHO regions have set measles elimination targets. However, a gap remains between current control levels and elimination targets, as shown by large measles outbreaks between 2017 and 2019. We aimed to model the potential for measles and rubella elimination globally to inform a WHO report to the 73rd World Health Assembly on the feasibility of measles and rubella eradication. METHODS: In this study, we modelled the probability of measles and rubella elimination between 2020 and 2100 under different vaccination scenarios in 93 countries of interest. We evaluated measles and rubella burden and elimination across two national transmission models each (Dynamic Measles Immunisation Calculation Engine [DynaMICE], Pennsylvania State University [PSU], Johns Hopkins University, and Public Health England models), and one subnational measles transmission model (Institute for Disease Modeling model). The vaccination scenarios included a so-called business as usual approach, which continues present vaccination coverage, and an intensified investment approach, which increases coverage into the future. The annual numbers of infections projected by each model, country, and vaccination scenario were used to explore if, when, and for how long the infections would be below a threshold for elimination. FINDINGS: The intensified investment scenario led to large reductions in measles and rubella incidence and burden. Rubella elimination is likely to be achievable in all countries and measles elimination is likely in some countries, but not all. The PSU and DynaMICE national measles models estimated that by 2050, the probability of elimination would exceed 75% in 14 (16%) and 36 (39%) of 93 modelled countries, respectively. The subnational model of measles transmission highlighted inequity in routine coverage as a likely driver of the continuance of endemic measles transmission in a subset of countries. INTERPRETATION: To reach regional elimination goals, it will be necessary to innovate vaccination strategies and technologies that increase spatial equity of routine vaccination, in addition to investing in existing surveillance and outbreak response programmes. FUNDING: WHO, Gavi, the Vaccine Alliance, US Centers for Disease Control and Prevention, and the Bill & Melinda Gates Foundation. |
Progress toward rubella and congenital rubella syndrome control and elimination - worldwide, 2012-2020
Zimmerman LA , Knapp JK , Antoni S , Grant GB , Reef SE . MMWR Morb Mortal Wkly Rep 2022 71 (6) 196-201 Rubella virus is a leading cause of vaccine-preventable birth defects and can cause epidemics. Although rubella virus infection usually produces a mild febrile rash illness in children and adults, infection during pregnancy, especially during the first trimester, can result in miscarriage, fetal death, stillbirth, or an infant born with a constellation of birth defects known as congenital rubella syndrome (CRS). A single dose of rubella-containing vaccine (RCV) can provide lifelong protection against rubella (1). The Global Vaccine Action Plan 2011-2020 (GVAP) included a target to achieve elimination of rubella in at least five of the six World Health Organization (WHO) regions* by 2020 (2), and WHO recommends capitalizing on the accelerated measles elimination activities as an opportunity to introduce RCV (1). This report updates a previous report (3) and summarizes global progress toward control and elimination of rubella and CRS from 2012, when accelerated rubella control activities were initiated, through 2020. Among 194 WHO Member States, the number with RCV in their immunization schedules has increased from 132 (68%) in 2012 to 173 (89%) in 2020; 70% of the world's infants were vaccinated against rubella in 2020. Reported rubella cases declined by 48%, from 94,277 in 2012 to 49,136 in 2019, and decreased further to 10,194 in 2020. Rubella elimination has been verified in 93 (48%) of 194 countries including the entire Region of the Americas (AMR). To increase the equity of protection and make further progress to eliminate rubella, it is important that the 21 countries that have not yet done so should introduce RCV. Likewise, countries that have introduced RCV can achieve and maintain rubella elimination with high vaccination coverage and surveillance for rubella and CRS. Four of six WHO regions have established rubella elimination goals; the two WHO regions that have not yet established an elimination goal (the African [AFR] and Eastern Mediterranean [EMR] regions) have expressed a commitment to rubella elimination and should consider establishing a goal. |
Progress toward rubella elimination - Western Pacific Region, 2000-2019
Knapp JK , Mariano KM , Pastore R , Grabovac V , Takashima Y , Alexander JP Jr , Reef SE , Hagan JE . MMWR Morb Mortal Wkly Rep 2020 69 (24) 744-750 Rubella is the leading vaccine-preventable cause of birth defects. Rubella typically manifests as a mild febrile rash illness; however, infection during pregnancy, particularly during the first trimester, can result in miscarriage, fetal death, or a constellation of malformations known as congenital rubella syndrome (CRS), commonly including one or more visual, auditory, or cardiac defects (1). In 2012, the Regional Committee of the World Health Organization (WHO) Western Pacific Region (WPR)* committed to accelerate rubella control, and in 2017, resolved that all countries or areas (countries) in WPR should aim for rubella elimination(dagger) as soon as possible (2,3). WPR countries are capitalizing on measles elimination activities, using a combined measles and rubella vaccine, case-based surveillance for febrile rash illness, and integrated diagnostic testing for measles and rubella. This report summarizes progress toward rubella elimination and CRS prevention in WPR during 2000-2019. Coverage with a first dose of rubella-containing vaccine (RCV1) increased from 11% in 2000 to 96% in 2019. During 1970-2019, approximately 84 million persons were vaccinated through 62 supplementary immunization activities (SIAs) conducted in 27 countries. Reported rubella incidence increased from 35.5 to 71.3 cases per million population among reporting countries during 2000-2008, decreased to 2.1 in 2017, and then increased to 18.4 in 2019 as a result of outbreaks in China and Japan. Strong sustainable immunization programs, closing of existing immunity gaps, and maintenance of high-quality surveillance to respond rapidly to and contain outbreaks are needed in every WPR country to achieve rubella elimination in the region. |
Progress toward rubella and congenital rubella syndrome control and elimination - worldwide, 2000-2018
Grant GB , Desai S , Dumolard L , Kretsinger K , Reef SE . MMWR Morb Mortal Wkly Rep 2019 68 (39) 855-859 Rubella is a leading cause of vaccine-preventable birth defects. Although rubella virus infection usually causes a mild febrile rash illness in children and adults, infection during pregnancy, especially during the first trimester, can result in miscarriage, fetal death, stillbirth, or a constellation of birth defects known as congenital rubella syndrome (CRS). A single dose of rubella-containing vaccine (RCV) can provide lifelong protection (1). In 2011, the World Health Organization (WHO) updated guidance on the use of RCV and recommended capitalizing on the accelerated measles elimination activities as an opportunity to introduce RCV (1). The Global Vaccine Action Plan 2011-2020 (GVAP) includes a target to achieve elimination of rubella in at least five of the six WHO regions by 2020 (2). This report on the progress toward rubella and CRS control and elimination updates the 2017 report (3), summarizing global progress toward the control and elimination of rubella and CRS from 2000 (the initiation of accelerated measles control activities) and 2012 (the initiation of accelerated rubella control activities) to 2018 (the most recent data) using WHO immunization and surveillance data. Among WHO Member States,* the number with RCV in their immunization schedules has increased from 99 (52% of 191) in 2000 to 168 (87% of 194) in 2018(dagger); 69% of the world's infants were vaccinated against rubella in 2018. Rubella elimination has been verified in 81 (42%) countries. To make further progress to control and eliminate rubella, and to reduce the equity gap, introduction of RCV in all countries is important. Likewise, countries that have introduced RCV can achieve and maintain elimination with high vaccination coverage and surveillance for rubella and CRS. The two WHO regions that have not established an elimination goal (African [AFR] and Eastern Mediterranean [EMR]) should consider establishing a goal.( section sign). |
Combining serological and contact data to derive target immunity levels for achieving and maintaining measles elimination
Funk S , Knapp JK , Lebo E , Reef SE , Dabbagh AJ , Kretsinger K , Jit M , Edmunds WJ , Strebel PM . BMC Med 2019 17 (1) 180 BACKGROUND: Vaccination has reduced the global incidence of measles to the lowest rates in history. However, local interruption of measles virus transmission requires sustained high levels of population immunity that can be challenging to achieve and maintain. The herd immunity threshold for measles is typically stipulated at 90-95%. This figure does not easily translate into age-specific immunity levels required to interrupt transmission. Previous estimates of such levels were based on speculative contact patterns based on historical data from high-income countries. The aim of this study was to determine age-specific immunity levels that would ensure elimination of measles when taking into account empirically observed contact patterns. METHODS: We combined estimated immunity levels from serological data in 17 countries with studies of age-specific mixing patterns to derive contact-adjusted immunity levels. We then compared these to case data from the 10 years following the seroprevalence studies to establish a contact-adjusted immunity threshold for elimination. We lastly combined a range of hypothetical immunity profiles with contact data from a wide range of socioeconomic and demographic settings to determine whether they would be sufficient for elimination. RESULTS: We found that contact-adjusted immunity levels were able to predict whether countries would experience outbreaks in the decade following the serological studies in about 70% of countries. The corresponding threshold level of contact-adjusted immunity was found to be 93%, corresponding to an average basic reproduction number of approximately 14. Testing different scenarios of immunity with this threshold level using contact studies from around the world, we found that 95% immunity would have to be achieved by the age of five and maintained across older age groups to guarantee elimination. This reflects a greater level of immunity required in 5-9-year-olds than established previously. CONCLUSIONS: The immunity levels we found necessary for measles elimination are higher than previous guidance. The importance of achieving high immunity levels in 5-9-year-olds presents both a challenge and an opportunity. While such high levels can be difficult to achieve, school entry provides an opportunity to ensure sufficient vaccination coverage. Combined with observations of contact patterns, further national and sub-national serological studies could serve to highlight key gaps in immunity that need to be filled in order to achieve national and regional measles elimination. |
Rubella vaccine - a tale of appropriate caution and remarkable success
Zimmerman LA , Reef SE , Orenstein WA . JAMA Pediatr 2018 172 (1) 95-96 Lyerly et al refer to historical aspects of the rubella vaccination program as “a cautionary tale about caution” concerning Zika vaccine research.1 The US rubella vaccination program has been a tale of appropriate caution and a remarkable success in rubella and congenital rubella syndrome (CRS) elimination2. We concur with the authors' assertion that safety studies in pregnant women are important and could have overcome the initial reluctance to give rubella vaccine to women of childbearing age (WCBA). However, points within the article warrant comment. |
Progress in rubella and congenital rubella syndrome control and elimination - worldwide, 2000-2016
Grant GB , Reef SE , Patel M , Knapp JK , Dabbagh A . MMWR Morb Mortal Wkly Rep 2017 66 (45) 1256-1260 Although rubella virus infection usually causes a mild fever and rash illness in children and adults, infection during pregnancy, especially during the first trimester, can result in miscarriage, fetal death, stillbirth, or infants with a constellation of congenital malformations known as congenital rubella syndrome (CRS) (1). Rubella is a leading vaccine-preventable cause of birth defects. Preventing these adverse pregnancy outcomes is the focus of rubella vaccination programs. In 2011, the World Health Organization (WHO) updated guidance on the preferred strategy for introduction of rubella-containing vaccine (RCV) into national immunization schedules and recommended an initial vaccination campaign, usually targeting children aged 9 months-14 years (1). The Global Vaccine Action Plan 2011-2020 (GVAP), endorsed by the World Health Assembly in 2012, includes goals to eliminate rubella in at least five of the six WHO regions by 2020 (2). This report updates a previous report (3) and summarizes global progress toward rubella and CRS control and elimination from 2000 to 2016. As of December 2016, 152 (78%) of 194 countries had introduced RCV into the national immunization schedule, representing an increase of 53 countries since 2000, including 20 countries that introduced RCV after 2012. |
Hospital-based surveillance of congenital rubella syndrome in Indonesia
Herini ES , Gunadi , Triono A , Mulyadi AW , Mardin N , Rusipah , Soenarto Y , Reef SE . Eur J Pediatr 2017 176 (3) 387-393 Congenital rubella syndrome (CRS) has serious consequences, such as miscarriage, stillbirth, and severe birth defects in infants, resulting from rubella virus infection during pregnancy. However, rubella vaccine has not yet been implemented in Indonesia. This study aimed (1) to estimate the incidence of CRS in Indonesia, (2) describe the clinical features of CRS at our referral hospital, and (3) pilot a CRS surveillance system to be extended to other hospitals. We conducted a 4-month prospective surveillance study of infants aged <1 year with suspected CRS in 2013 at an Indonesian hospital. Infants with suspected CRS were examined for rubella-specific IgM antibody or rubella IgG antibody levels. Of 47 suspected cases of CRS, 11/47 (23.4%), 9/47 (19.1%), and 27/47 (57.5%) were diagnosed as laboratory-confirmed, clinically compatible, and discarded CRS, respectively. The most common defects among laboratory-confirmed CRS cases were hearing impairment (100%), congenital cataracts (72.7%), microcephaly (72.7%), and congenital heart defects (45.5%). CONCLUSION: The number of laboratory-confirmed CRS cases among Indonesian infants is high. Furthermore, hearing impairment is the most common clinical feature of CRS in infants. Our findings indicate the importance of implementation of rubella vaccine in Indonesia. Conducting hospital-based surveillance of CRS in other hospitals in Indonesia may be appropriate. What is Known: *Congenital rubella syndrome (CRS) has serious consequences in infants resulting from rubella virus infection during pregnancy. *The incidence of CRS in most developed countries has greatly decreased since implementation of rubella vaccination. *Rubella vaccine has not yet been implemented in many developing countries. What is New: *The number of laboratory-confirmed CRS cases among Indonesian infants was high. *Implementation of rubella vaccine into immunization programs in Indonesia is important because of the high number of CRS cases. *Our study highlights the need for ongoing prospective surveillance of CRS in Indonesia. |
Estimating the burden of rubella virus infection and congenital rubella syndrome through a rubella immunity assessment among pregnant women in the Democratic Republic of the Congo: Potential impact on vaccination policy
Alleman MM , Wannemuehler KA , Hao L , Perelygina L , Icenogle JP , Vynnycky E , Fwamba F , Edidi S , Mulumba A , Sidibe K , Reef SE . Vaccine 2016 34 (51) 6502-6511 BACKGROUND: Rubella-containing vaccines (RCV) are not yet part of the Democratic Republic of the Congo's (DRC) vaccination program; however RCV introduction is planned before 2020. Because documentation of DRC's historical burden of rubella virus infection and congenital rubella syndrome (CRS) has been minimal, estimates of the burden of rubella virus infection and of CRS would help inform the country's strategy for RCV introduction. METHODS: A rubella antibody seroprevalence assessment was conducted using serum collected during 2008-2009 from 1605 pregnant women aged 15-46years attending 7 antenatal care sites in 3 of DRC's provinces. Estimates of age- and site-specific rubella antibody seroprevalence, population, and fertility rates were used in catalytic models to estimate the incidence of CRS per 100,000 live births and the number of CRS cases born in 2013 in DRC. RESULTS: Overall 84% (95% CI 82, 86) of the women tested were estimated to be rubella antibody seropositive. The association between age and estimated antibody seroprevalence, adjusting for study site, was not significant (p=0.10). Differences in overall estimated seroprevalence by study site were observed indicating variation by geographical area (p0.03 for all). Estimated seroprevalence was similar for women declaring residence in urban (84%) versus rural (83%) settings (p=0.67). In 2013 for DRC nationally, the estimated incidence of CRS was 69/100,000 live births (95% CI 0, 186), corresponding to 2886 infants (95% CI 342, 6395) born with CRS. CONCLUSIONS: In the 3 provinces, rubella virus transmission is endemic, and most viral exposure and seroconversion occurs before age 15years. However, approximately 10-20% of the women were susceptible to rubella virus infection and thus at risk for having an infant with CRS. This analysis can guide plans for introduction of RCV in DRC. Per World Health Organization recommendations, introduction of RCV should be accompanied by a campaign targeting all children 9months to 14years of age as well as vaccination of women of child bearing age through routine services. |
Characterization of the risks of adverse outcomes following rubella infection in pregnancy
Thompson KM , Simons EA , Badizadegan K , Reef SE , Cooper LZ . Risk Anal 2016 36 (7) 1315-31 Although most infections with the rubella virus result in relatively minor sequelae, rubella infection in early pregnancy may lead to severe adverse outcomes for the fetus. First recognized in 1941, congenital rubella syndrome (CRS) can manifest with a diverse range of symptoms, including congenital cataracts, glaucoma, and cardiac defects, as well as hearing and intellectual disability. The gestational age of the fetus at the time of the maternal rubella infection impacts the probability and severity of outcomes, with infection in early pregnancy increasing the risks of spontaneous termination (miscarriage), fetal death (stillbirth), birth defects, and reduced survival for live-born infants. Rubella vaccination continues to change the epidemiology of rubella and CRS globally, but no models currently exist to evaluate the economic benefits of rubella management. This systematic review provides an overall assessment of the weight of the evidence for the outcomes associated with rubella infections in the first 20 weeks of pregnancy. We identified, evaluated, and graded 31 studies (all from developed countries) that reported on the pregnancy outcomes of at least 30 maternal rubella infections. We used the available evidence to estimate the increased risks of spontaneous termination, fetal death, infant death, and CRS as a function of the timing of rubella infection in pregnancy and decisions about induced termination. These data support the characterization of the disability-adjusted life years for outcomes associated with rubella infection in pregnancy. We find significant impacts associated with maternal rubella infections in early pregnancy, which economic analyses will miss if they only focus on live births of CRS cases. Our estimates of fetal loss from increased induced terminations due to maternal rubella infections provide context that may help to explain the relatively low numbers of observed CRS cases per year despite potentially large burdens of disease. Our comprehensive review of the weight of the evidence of all pregnancy outcomes demonstrates the importance of including all outcomes in models that characterize rubella-related disease burdens and costs. |
Systematic review of the manifestations of congenital rubella syndrome in infants and characterization of disability-adjusted life years (DALYs)
Simons EA , Reef SE , Cooper LZ , Zimmerman L , Thompson KM . Risk Anal 2016 36 (7) 1332-56 Congenital rubella syndrome (CRS) continues to cause disability among unvaccinated populations in countries with no or insufficient rubella vaccine coverage to prevent transmission. We systematically reviewed the literature on birth outcomes associated with CRS to estimate the duration, severity, and frequency of combinations of morbidities. We searched PubMed, the Science Citation Index, and references from relevant articles for studies in English with primary data on the frequency of CRS manifestations for ≥20 cases and identified 65 studies representing 66 study populations that met our inclusion criteria. We abstracted available data on CRS cases with one or more hearing, heart, and/or eye defect following maternal rubella infection during the period of 0-20 weeks since the last menstrual period. We assessed the quality and weight of the available evidence using a modified Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Most of the evidence originates from studies in developed countries of cohorts of infants identified with CRS in the 1960s and 1970s, prior to the development of standardized definitions for CRS and widespread use of vaccine. We developed estimates of undiscounted disability-adjusted life years (DALYs) lost per CRS case for countries of different income levels. The estimates ranged from approximately 19 to 39 for high-income countries assuming optimal treatment and from approximately 29 to 39 DALYs lost per CRS case in low- and lower- middle-income countries assuming minimal treatment, with the lower bound based on 2010 general global burden of disease disability weights and the upper bound based on 1990 age-specific and treatment-specific global burden of disease disability weights. Policymakers and analysts should appreciate the significant burden of disability caused by CRS as they evaluate opportunities to manage rubella. |
Using seroprevalence and immunisation coverage data to estimate the global burden of Congenital Rubella Syndrome, 1996-2010: A systematic review
Vynnycky E , Adams EJ , Cutts FT , Reef SE , Navar AM , Simons E , Yoshida LM , Brown DW , Jackson C , Strebel PM , Dabbagh AJ . PLoS One 2016 11 (3) e0149160 BACKGROUND: The burden of Congenital Rubella Syndrome (CRS) is typically underestimated in routine surveillance. Updated estimates are needed following the recent WHO position paper on rubella and recent GAVI initiatives, funding rubella vaccination in eligible countries. Previous estimates considered the year 1996 and only 78 (developing) countries. METHODS: We reviewed the literature to identify rubella seroprevalence studies conducted before countries introduced rubella-containing vaccination (RCV). These data and the estimated vaccination coverage in the routine schedule and mass campaigns were incorporated in mathematical models to estimate the CRS incidence in 1996 and 2000-2010 for each country, region and globally. RESULTS: The estimated CRS decreased in the three regions (Americas, Europe and Eastern Mediterranean) which had introduced widespread RCV by 2010, reaching <2 per 100,000 live births (the Americas and Europe) and 25 (95% CI 4-61) per 100,000 live births (the Eastern Mediterranean). The estimated incidence in 2010 ranged from 90 (95% CI: 46-195) in the Western Pacific, excluding China, to 116 (95% CI: 56-235) and 121 (95% CI: 31-238) per 100,000 live births in Africa and SE Asia respectively. Highest numbers of cases were predicted in Africa (39,000, 95% CI: 18,000-80,000) and SE Asia (49,000, 95% CI: 11,000-97,000). In 2010, 105,000 (95% CI: 54,000-158,000) CRS cases were estimated globally, compared to 119,000 (95% CI: 72,000-169,000) in 1996. CONCLUSIONS: Whilst falling dramatically in the Americas, Europe and the Eastern Mediterranean after vaccination, the estimated CRS incidence remains high elsewhere. Well-conducted seroprevalence studies can help to improve the reliability of these estimates and monitor the impact of rubella vaccination. |
Identification of Serologic Markers for School-Aged Children With Congenital Rubella Syndrome
Hyde TB , Sato HK , Hao L , Flannery B , Zheng Q , Wannemuehler K , Ciccone FH , de Sousa Marques H , Weckx LY , Sáfadi MA , de Oliveira Moraes E , Pinhata MM , Olbrich Neto J , Bevilacqua MC , Tabith Junior A , Monteiro TA , Figueiredo CA , Andrus JK , Reef SE , Toscano CM , Castillo-Solorzano C , Icenogle JP . J Infect Dis 2015 212 (1) 57-66 BACKGROUND: Congenital rubella syndrome (CRS) case identification is challenging in older children since laboratory markers of congenital rubella virus (RUBV) infection do not persist beyond age 12 months. METHODS: We enrolled children with CRS born between 1998 and 2003 and compared their immune responses to RUBV with those of their mothers and a group of similarly aged children without CRS. Demographic data and sera were collected. Sera were tested for anti-RUBV immunoglobulin G (IgG), IgG avidity, and IgG response to the 3 viral structural proteins (E1, E2, and C), reflected by immunoblot fluorescent signals. RESULTS: We enrolled 32 children with CRS, 31 mothers, and 62 children without CRS. The immunoblot signal strength to C and the ratio of the C signal to the RUBV-specific IgG concentration were higher (P < .029 for both) and the ratio of the E1 signal to the RUBV-specific IgG concentration lower (P = .001) in children with CRS, compared with their mothers. Compared with children without CRS, children with CRS had more RUBV-specific IgG (P < .001), a stronger C signal (P < .001), and a stronger E2 signal (P ≤ .001). Two classification rules for children with versus children without CRS gave 100% specificity with >65% sensitivity. CONCLUSIONS: This study was the first to establish classification rules for identifying CRS in school-aged children, using laboratory biomarkers. These biomarkers should allow improved burden of disease estimates and monitoring of CRS control programs. |
Global progress toward rubella and congenital rubella syndrome control and elimination - 2000-2014
Grant GB , Reef SE , Dabbagh A , Gacic-Dobo M , Strebel PM . MMWR Morb Mortal Wkly Rep 2015 64 (37) 1052-1055 Rubella virus usually causes a mild fever and rash in children and adults. However, infection during pregnancy, especially during the first trimester, can result in miscarriage, fetal death, stillbirth, or a constellation of congenital malformations known as congenital rubella syndrome (CRS). In 2011, the World Health Organization (WHO) updated guidance on the preferred strategy for introduction of rubella-containing vaccine (RCV) into national routine immunization schedules, including an initial vaccination campaign usually targeting children aged 9 months-15 years . The Global Vaccine Action Plan endorsed by the World Health Assembly in 2012 and the Global Measles and Rubella Strategic Plan (2012-2020) published by Measles and Rubella Initiative partners in 2012 both include goals to eliminate rubella and CRS in at least two WHO regions by 2015, and at least five WHO regions by 2020 (2,3). This report updates a previous report and summarizes global progress toward rubella and CRS control and elimination during 2000-2014. As of December 2014, RCV had been introduced in 140 (72%) countries, an increase from 99 (51%) countries in 2000 (for this report, WHO member states are referred to as countries). Reported rubella cases declined 95%, from 670,894 cases in 102 countries in 2000 to 33,068 cases in 162 countries in 2014, although reporting is inconsistent. To achieve the 2020 Global Vaccine Action Plan rubella and CRS elimination goals, RCV introduction needs to continue as country criteria indicating readiness are met, and rubella and CRS surveillance need to be strengthened to ensure that progress toward elimination can be measured. |
Synthesis of evidence to characterize national measles and rubella exposure and immunization histories
Thompson KM , Odahowski CL , Goodson JL , Reef SE , Perry RT . Risk Anal 2015 36 (7) 1427-58 Population immunity depends on the dynamic levels of immunization coverage that countries achieve over time and any transmission of viruses that occur within the population that induce immunity. In the context of developing a dynamic transmission model for measles and rubella to support analyses of future immunization policy options, we assessed the model inputs required to reproduce past behavior and to provide some confidence about model performance at the national level. We reviewed the data available from the World Health Organization (WHO) and existing measles and rubella literature for evidence of historical reported routine and supplemental immunization activities and reported cases and outbreaks. We constructed model input profiles for 180 WHO member states and three other areas to support disease transmission model development and calibration. The profiles demonstrate the significant variability in immunization strategies used historically by regions and member states and the epidemiological implications of these historical choices. The profiles provide a historical perspective on measles and rubella immunization globally at the national level, and they may help immunization program managers identify existing immunity and/or knowledge gaps. |
Elimination of endemic measles, rubella, and congenital rubella syndrome from the Western hemisphere: the US experience.
Papania MJ , Wallace GS , Rota PA , Icenogle JP , Fiebelkorn AP , Armstrong GL , Reef SE , Redd SB , Abernathy ES , Barskey AE , Hao L , McLean HQ , Rota JS , Bellini WJ , Seward JF . JAMA Pediatr 2013 168 (2) 148-55 ![]() IMPORTANCE: To verify the elimination of endemic measles, rubella, and congenital rubella syndrome (CRS) from the Western hemisphere, the Pan American Health Organization requested each member country to compile a national elimination report. The United States documented the elimination of endemic measles in 2000 and of endemic rubella and CRS in 2004. In December 2011, the Centers for Disease Control and Prevention convened an external expert panel to review the evidence and determine whether elimination of endemic measles, rubella, and CRS had been sustained. OBJECTIVE: To review the evidence for sustained elimination of endemic measles, rubella, and CRS from the United States through 2011. DESIGN, SETTING, AND PARTICIPANTS: Review of data for measles from 2001 to 2011 and for rubella and CRS from 2004 to 2011 covering the US resident population and international visitors, including disease epidemiology, importation status of cases, molecular epidemiology, adequacy of surveillance, and population immunity as estimated by national vaccination coverage and serologic surveys. MAIN OUTCOMES AND MEASURES: Annual numbers of measles, rubella, and CRS cases, by importation status, outbreak size, and distribution; proportions of US population seropositive for measles and rubella; and measles-mumps-rubella vaccination coverage levels. RESULTS: Since 2001, US reported measles incidence has remained below 1 case per 1 000 000 population. Since 2004, rubella incidence has been below 1 case per 10 000 000 population, and CRS incidence has been below 1 case per 5 000 000 births. Eighty-eight percent of measles cases and 54% of rubella cases were internationally imported or epidemiologically or virologically linked to importation. The few cases not linked to importation were insufficient to represent endemic transmission. Molecular epidemiology indicated no endemic genotypes. The US surveillance system is adequate to detect endemic measles or rubella. Seroprevalence and vaccination coverage data indicate high levels of population immunity to measles and rubella. CONCLUSIONS AND RELEVANCE: The external expert panel concluded that the elimination of endemic measles, rubella, and CRS from the United States was sustained through 2011. However, international importation continues, and health care providers should suspect measles or rubella in patients with febrile rash illness, especially when associated with international travel or international visitors, and should report suspected cases to the local health department. |
The estimated mortality impact of vaccinations forecast to be administered during 2011-2020 in 73 countries supported by the GAVI Alliance
Lee LA , Franzel L , Atwell J , Datta SD , Friberg IK , Goldie SJ , Reef SE , Schwalbe N , Simons E , Strebel PM , Sweet S , Suraratdecha C , Tam Y , Vynnycky E , Walker N , Walker DG , Hansen PM . Vaccine 2013 31 Suppl 2 B61-72 INTRODUCTION: From August to December 2011, a multidisciplinary group with expertise in mathematical modeling was constituted by the GAVI Alliance and the Bill & Melinda Gates Foundation to estimate the impact of vaccination in 73 countries supported by the GAVI Alliance. METHODS: The number of deaths averted in persons projected to be vaccinated during 2011-2020 was estimated for ten antigens: hepatitis B, yellow fever, Haemophilus influenzae type B (Hib), Streptococcus pneumoniae, rotavirus, Neisseria meningitidis serogroup A, Japanese encephalitis, human papillomavirus, measles, and rubella. Impact was calculated as the difference in the number of deaths expected over the lifetime of vaccinated cohorts compared to the number of deaths expected in those cohorts with no vaccination. Numbers of persons vaccinated were based on 2011 GAVI Strategic Demand Forecasts with projected dates of vaccine introductions, vaccination coverage, and target population size in each country. RESULTS: By 2020, nearly all GAVI-supported countries with endemic disease are projected to have introduced hepatitis B, Hib, pneumococcal, rotavirus, rubella, yellow fever, N. meningitidis serogroup A, and Japanese encephalitis-containing vaccines; 55 (75 percent) countries are projected to have introduced human papillomavirus vaccine. Projected use of these vaccines during 2011-2020 is expected to avert an estimated 9.9 million deaths. Routine and supplementary immunization activities with measles vaccine are expected to avert an additional 13.4 million deaths. Estimated numbers of deaths averted per 1000 persons vaccinated were highest for first-dose measles (16.5), human papillomavirus (15.1), and hepatitis B (8.3) vaccination. Approximately 52 percent of the expected deaths averted will be in Africa, 27 percent in Southeast Asia, and 13 percent in the Eastern Mediterranean. CONCLUSION: Vaccination of persons during 2011-2020 in 73 GAVI-eligible countries is expected to have substantial public health impact, particularly in Africa and Southeast Asia, two regions with high mortality. The actual impact of vaccination in these countries may be higher than our estimates because several widely used antigens were not included in the analysis. The quality of our estimates is limited by lack of data on underlying disease burden and vaccine effectiveness against fatal disease outcomes in developing countries. We plan to update the estimates annually to reflect updated demand forecasts, to refine model assumptions based on results of new information, and to extend the analysis to include morbidity and economic benefits. |
Reducing the global burden of congenital rubella syndrome
Reef SE , Chu SY , Cochi SL , Kezaala R , van den Ent M , Gay A , de Quadros C , Strebel PM . Lancet 2012 380 (9848) 1145-6 In their Correspondence letter (July 21, p 217),1 F T Cutts and colleagues highlight challenges to rubella vaccination programmes that might arise with GAVI Alliance support for eligible countries to introduce rubella-containing vaccines. We wholeheartedly agree that expansion of rubella vaccination programmes cannot be “business as usual”. | Issues such as disparities in coverage, pockets of susceptibility, and targeted vaccination of women of childbearing age highlighted by Cutts and colleagues were also addressed in a recently published WHO position paper on rubella vaccine.2 The position paper stresses the need for strong routine vaccination programmes and supplemental immunisation activities to achieve high rubella vaccination coverage (≥80%), and efforts to reach women of childbearing age. Although GAVI Alliance support does not directly fund strategies for vaccination of such women, the board called on governments to fund additional vaccination efforts for this group. |
Measles, rubella, and varicella among the crew of a cruise ship sailing from Florida, United States, 2006
Mitruka K , Felsen CB , Tomianovic D , Inman B , Street K , Yambor P , Reef SE . J Travel Med 2012 19 (4) 233-7 BACKGROUND: Cruise ship outbreaks of vaccine-preventable diseases (VPD) such as rubella and varicella have been previously associated with introduction and spread among susceptible crew members originating from countries with endemic transmission of these diseases. METHODS: During February to April 2006, we investigated a cluster of rash illnesses due to measles, rubella, or varicella on a cruise ship sailing from Florida to the Caribbean. Case-finding measures included review of medical logs, active surveillance for rash illness among crew members, and passive surveillance for rash illness in the ship's infirmary lasting two incubation periods from the last case of measles. Passengers with potential exposure to these VPD were notified by letters. All susceptible crew members with potential exposure were administered the measles, mumps, and rubella vaccine after informed consent. RESULTS: A total of 16 cases were identified only among crew members: 1 rubella, 3 measles (two-generation spread), 11 varicella (three-generation spread), and 1 unknown diagnosis. Of 1,197 crew members evaluated, 4 had proof of immunity to measles and rubella. Based on passive surveillance, no cases were identified among passengers, the majority of whom resided in the United States. CONCLUSION: The international makeup of the population aboard cruise ships combined with their semi-enclosed environment has the potential to facilitate introduction and spread of VPD such as measles, rubella, and varicella onboard and into communities. Cruise lines should ensure crew members have evidence of immunity to these diseases. Passengers should be up to date with all vaccinations, including those that are travel-specific, prior to embarking on cruise travel. |
Virologic surveillance for wild-type rubella viruses in the Americas
Icenogle JP , Siqueira MM , Abernathy ES , Lemos XR , Fasce RA , Torres G , Reef SE . J Infect Dis 2011 204 Suppl 2 S647-51 The goal of eliminating rubella from the Americas by 2010 was established in 2003. Subsequently, a systematic nomenclature for wild-type rubella viruses (wtRVs) was established, wtRVs circulating in the region were catalogued, and importations of wtRVs into a number of countries were documented. The geographic distribution of wtRVs of various genotypes in the Americas, interpreted in the context of the global distribution of these viruses, contributed to the documentation of rubella elimination from some countries. Data from virologic surveillance also contributed to the conclusion that viruses of genotype 2B began circulating endemically in the Americas during 2006-2007. Viruses of one genotype (1C), which are restricted to the Americas, will likely disappear completely from the world as they are eliminated from the Americas. Efforts to expand virologic surveillance for wtRVs in the Americas will also provide additional data aiding the elimination of rubella from the region. For example, identification of vaccine virus in specimens from rash and fever cases found during elimination can identify such cases as vaccine associated. |
Evidence used to support the achievement and maintenance of elimination of rubella and congenital rubella syndrome in the United States
Reef SE , Redd SB , Abernathy E , Kutty P , Icenogle JP . J Infect Dis 2011 204 Suppl 2 S593-7 On 29 October 2004, an expert panel was convened to review the status of elimination of rubella and congenital rubella syndrome (CRS) in the United States. Primarily based on 5 types of information presented-epidemiology of reported cases, molecular epidemiology, seroprevalence, vaccine coverage, and adequacy of surveillance-the panel unanimously agreed that rubella virus is no longer endemic in the United States. Since 2004, new data continue to support the conclusion that elimination has been achieved and maintained. In documenting elimination in the United States, each of the 5 types of data provided evidence for elimination and collectively provided much stronger evidence than any one type could individually. As countries document the elimination of rubella and CRS, many sources and types of data will likely be necessary. Rigorous data evaluation must be conducted to look for inconsistencies among the available data. To maintain elimination, countries should maintain high vaccine coverage, adequate surveillance, and rapid response to outbreaks. |
Guidelines for the documentation and verification of measles, rubella, and congenital rubella syndrome elimination in the region of the Americas
Castillo-Solorzano C , Reef SE , Morice A , Andrus JK , Ruiz Matus C , Tambini G , Gross-Galiano S . J Infect Dis 2011 204 Suppl 2 S683-9 In the region of the Americas, goals for the elimination of endemic measles and rubella/congenital rubella syndrome (CRS) by the year 2000 and 2010, respectively were established. The successful implementation of measles elimination strategies in the region of the Americas resulted in the interruption of endemic measles transmission in 2002 and tremendous progress toward rubella and CRS elimination. In October 2007, the 27th Pan American Sanitary Conference adopted Resolution CSP27.R2 urging member states to begin documenting and verifying the interruption of endemic transmission of the measles and rubella viruses in the Americas. To ensure a standardized approach for the process of documentation and verification, the Pan American Health Organization/World Health Organization (PAHO/WHO) developed a regional plan of action to guide countries and their national commissions as they prepare and consolidate evidence of the interruption of endemic measles and rubella transmission. This article summarizes the plan of action including the essential criteria and components of the guidelines. |
Progress toward control of rubella and prevention of congenital rubella syndrome--worldwide, 2009
Reef SE , Strebel P , Dabbagh A , Gacic-Dobo M , Cochi S . J Infect Dis 2011 204 Suppl 1 S24-7 Rubella, usually a mild rash illness in children and adults, can cause serious consequences when a pregnant woman is infected, particularly in early pregnancy. These serious consequences include miscarriage, fetal death or an infant born with birth defects (i.e., congenital rubella syndrome (CRS)). The primary purpose for rubella vaccination is the prevention of congenital rubella infection including CRS. Since 1969, several rubella virus vaccines have been licensed for use; however, until the 1990s, use of rubella-containing vaccine (RCV) was limited primarily to developed countries. In 1996, it was estimated that 110,000 infants with CRS were born annually in developing countries. In 2000, the first World Health Organization rubella vaccine position paper was published to guide introduction of RCV in national childhood immunization schedules. From 1996 to 2009, the number of countries that introduced RCV into their national routine childhood immunization programs increased by 57% from 83 countries in 1996 to 130 countries in 2009. In addition, three of the six WHO regions established rubella control and CRS prevention goals: Region of the Americas and Europe rubella elimination by 2010 and 2015, respectively, and Western Pacific Region-accelerated rubella control and CRS prevention by 2015. Also, during this time period, the number of rubella cases reported decreased from 670,894 in 2000 to 121,344 in 2009. Rubella control and prevention of CRS can be accelerated by integrating with current global measles mortality reduction and regional elimination activities. |
Measles outbreak associated with an international youth sporting event in the United States, 2007
Chen TH , Kutty P , Lowe LE , Hunt EA , Blostein J , Espinoza R , Dykewicz CA , Redd S , Rota JS , Rota PA , Lute JR , Lurie P , Nguyen MD , Moll M , Reef SE , Sinclair JR , Bellini WJ , Seward JF , Ostroff SM . Pediatr Infect Dis J 2010 29 (9) 794-800 ![]() BACKGROUND: Despite elimination of endemic measles in the United States (US), outbreaks associated with imported measles continue to occur. In 2007, the initiation of a multistate measles outbreak was associated with an imported case occurring in a participant at an international youth sporting event held in Pennsylvania. METHODS: Case finding and contact tracing were conducted. Control measures included isolating ill persons and administering postexposure prophylaxis to exposed persons without documented measles immunity. Laboratory evaluation of suspected cases and contacts included measles serologic testing, viral culture, detection of viral RNA by reverse-transcription polymerase chain reaction, and viral genotyping. RESULTS: The index case occurred in a child from Japan aged 12 years. Contact tracing among 1250 persons in 8 states identified 7 measles cases; 5 (71%) cases occurred among persons without documented measles vaccination. Epidemiologic and laboratory investigation supported a single chain of transmission, linking the outbreak to contemporaneous measles virus genotype D5 transmission in Japan. Of the 471 event participants, 193 (41%) lacked documentation of presumed measles immunity, 94 (49%) of 193 were US-resident adults, 19 (10%) were non-US-resident adults (aged >18 years), and 80 (41%) were non-US-resident children. DISCUSSION: Measles outbreaks associated with imported disease are likely to continue in the US. Participants in international events, international travelers, and persons with routine exposure to such travelers might be at greater risk of measles. To reduce the impact of imported cases, high measles, mumps, and rubella vaccine coverage rates should be maintained throughout the US, and support should continue for global measles control and elimination. |
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