Pregnancy is associated with increased risk for severe illness and complications associated with influenza infection. Insufficient knowledge about the risk for influenza among pregnant women and their health care providers in China is an important barrier to increasing influenza vaccination coverage and treating influenza and its complications among pregnant women. Improved influenza incidence estimates might promote wider vaccine acceptance and higher vaccination coverage. In Suzhou, active population-based surveillance during October 2018-September 2023 estimated that the annual rate of hospitalization for acute respiratory or febrile illness (ARFI) among women who were pregnant or <2 weeks postpartum was 11.1 per 1,000 live births; the annual rate of laboratory-confirmed influenza-associated ARFI (influenza ARFI) hospitalization in this group was 2.1 per 1,000 live births. A majority of hospitalized pregnant or early postpartum patients with ARFI (82.6%; 2,588 of 3,133) or influenza ARFI (85.5%; 423 of 495) were admitted to obstetrics wards rather than respiratory medicine wards. Only one (0.03%) pregnant or postpartum ARFI patient had received influenza vaccination, and 31.3% of pregnant or postpartum women hospitalized for influenza ARFI received antiviral treatment; the lowest percentage of hospitalized women with influenza ARFI who received antiviral treatment was among women admitted to obstetrics and gynecology wards (29.6% and 23.1%, respectively), compared with 54.1% of those admitted to a respiratory medicine ward. These findings highlight the risk for influenza and its associated complications among pregnant and postpartum women, the low rates of influenza vaccination among pregnant women, and of antiviral treatment of women with ARFI admitted to obstetrics and gynecology wards. Increasing awareness of the prevalence of influenza ARFI among pregnant women, the use of empiric antiviral treatment for ARFI, and the infection control in obstetrics wards during influenza seasons might help reduce influenza-associated morbidity among pregnant and postpartum women.

The US Centers for Disease Control and Prevention (CDC) supports international partners in introducing vaccines, including those against SARS-CoV-2 virus. CDC contributes to the development of global technical tools, guidance, and policy for COVID-19 vaccination and has established its COVID-19 International Vaccine Implementation and Evaluation (CIVIE) program. CIVIE supports ministries of health and their partner organizations in developing or strengthening their national capacities for the planning, implementation, and evaluation of COVID-19 vaccination programs. CIVIE's 7 priority areas for country-specific technical assistance are vaccine policy development, program planning, vaccine confidence and demand, data management and use, workforce development, vaccine safety, and evaluation. We discuss CDC's work on global COVID-19 vaccine implementation, including priorities, challenges, opportunities, and applicable lessons learned from prior experiences with Ebola, influenza, and meningococcal serogroup A conjugate vaccine introductions.

On January 6, 2022, a cluster of COVID-19 cases* caused by the Omicron variant of SARS-CoV-2, the virus that causes COVID-19, was detected in Hong Kong Special Administrative Region, China (Hong Kong), resulting in the territory's fifth wave of COVID-19 cases (1). This wave peaked on March 4, 2022, with 8,764 COVID-19 cases per million population (2), resulting in a total of 1,049,959 cases and 5,906 COVID-19-associated deaths reported to the Hong Kong Department of Health during January 6-March 21, 2022.() Throughout this period, the COVID-19 mortality rate in Hong Kong (37.7 per million population) was among the highest reported worldwide since the COVID-19 pandemic began (3). Publicly available data on age-specific vaccination coverage in Hong Kong with a 2-dose primary vaccination series (with either Sinovac-CoronaVac [Sinovac], an inactivated COVID-19 viral vaccine, recommended for persons aged 3 years or BNT162b2 [Pfizer-BioNTech], an mRNA vaccine, for persons aged 5 years), as of December 23, 2021,()(,)() and COVID-19 mortality during January 6-March 21, 2022, were analyzed. By December 23, 2021, 67% of vaccine-eligible persons in Hong Kong had received 1 dose of a COVID-19 vaccine, 64% had received 2 doses, and 5% had received a booster dose. Among persons aged 60 years, these proportions were 52%, 49%, and 7%, respectively. Among those aged 60 years, vaccination coverage declined with age: 48% of persons aged 70-79 years had received 1 dose, 45% received 2 doses, and 7% had received a booster, and among those aged 80 years, 20%, 18%, and 2% had received 1 dose, 2 doses, and a booster dose, respectively. Among 5,906 COVID-19 deaths reported, 5,655 (96%) occurred in persons aged 60 years**; among these decedents, 3,970 (70%) were unvaccinated, 18% (1,023) had received 1 vaccine dose, and 12% (662) had received 2 doses. The overall rates of COVID-19-associated mortality among persons aged 60 years who were unvaccinated, who had received 1 COVID-19 vaccine dose, and who had received 2 vaccine doses were 10,076, 1,099, and 473 per million population, respectively; the risk for COVID-19-associated death among unvaccinated persons was 21.3 times that among recipients of 2-3 doses in this age group. The high overall mortality rate during the ongoing 2022 Hong Kong Omicron COVID-19 outbreak is being driven by deaths among unvaccinated persons aged 60 years. Efforts to identify and address gaps in age-specific vaccination coverage can help prevent high mortality from COVID-19, especially among persons aged 60 years.

Health campaigns are time-bound, intermittent activities that address specific epidemiological challenges, expediently fill delivery gaps or provide surge coverage for health interventions. | They can be used to prevent or respond to disease outbreaks, control or eliminate targeted diseases as a public health problem, eradicate a disease altogether or achieve other health goals. | In 2020, more than 530 health campaigns were planned for 26 different interventions representing 13 diseases and 105 countries. | Due to the COVID-19 pandemic, by the end of last year, about half of planned campaigns were postponed, cancelled, or suspended leaving hundreds of millions of children and families at risk of vaccine-preventable diseases, tropical diseases and malnutrition. | So far in 2021, more than 280 campaigns have been cancelled or delayed. | As health campaigns restart and catch up on the delivery of missed drugs, vaccines and nutritional supplements, and countries roll out COVID-19 vaccines, there is an opportunity to rethink the way we plan and implement campaigns to improve their effectiveness and impact. |

The past decade began with a great deal of promise that after nearly 50 years of measles vaccine use to combat one of the major causes of global child mortality, a world without measles was finally in sight [1]. In 1980, before widespread global use of measles vaccine, an estimated 2.6 million measles deaths occurred worldwide. At the beginning of the 21st century, to accelerate the reduction in measles cases achieved by vaccination, a new strategy to deliver at least 2 doses of measles-containing vaccine (MCV) to all children, either through routine immunization services or supplementary immunization activities (SIAs), and to improve measles surveillance was launched by the founding partners of a new global Measles Initiative—the World Health Organization (WHO), the United Nations Children’s Fund (UNICEF), the Centers for Disease Control and Prevention, the United Nations Foundation, and the American Red Cross (the initiative was renamed the Measles and Rubella Initiative in 2012) [2]. During the first decade of this century, this initiative supported the vaccination of > 900 million children in SIAs and led to a decrease in global mortality attributed to measles by an impressive 78%, from an estimated 733 000 deaths in 2000 to 164 000 in 2008, as well as an increase in MCV first-dose routine immunization coverage (MCV1) from 72% to 85% during 2000–2010 [1]. Moreover, reductions in measles mortality accounted for a remarkable 23% of the overall estimated global decline in all-cause child mortality from 1990 to 2008 [3]. In the United States (US), measles was declared eliminated in 2000 as a result of sustained interruption of transmission.

All World Health Organization (WHO) Regions have goals to interrupt endemic measles circulation on or before 2020. This is a worthy, feasible (already achieved in the Region of the Americas) but formidable challenge, given the unique contagiousness of the measles virus, which demands homogeneous population immunity over 92% in most settings. High population immunity is necessary to ensure that the effective reproduction number is driven below 1, a pre-requisite for achieving and sustaining elimination. | | To provide guidance for verifying measles elimination, the WHO has published a framework that details evidence across five domains required to substantiate an individual country’s or Region’s claim to have interrupted endemic measles virus transmission. These evidence domains are: (1) a careful description of measles epidemiology over an extended period; (2) indicators of the quality of epidemiological and laboratory surveillance; (3) laboratory evidence of the absence of an endemic or, following importation, a sustained transmission measles genotype; (4) confirmation of immunisation program sustainability; and (5) measures of robust population immunity by birth cohort [1]. The accurate determination of population immunity is constrained by the inadequate quality of routinely available administrative data in many settings i.e., recording of vaccine doses administered either during the routine immunisation programme or by supplementary immunisation activities (SIAs) as the numerator, while the denominator is estimated from census data after considering births, deaths, and migration. Although vaccine coverage data appears an efficient means for estimating immunity, the quality of coverage data and routinely reported measles case data is extraordinarily variable globally and this seriously compromises the construction of credible immunity profiles across all age groups, at different spatial scales, and in population sub-groups. Disproportionate delivery of vaccine often occurs during non-selective SIAs with individuals who are already immune from prior vaccination being more readily accessible to the health system. They are thus more commonly revaccinated than persons never previously vaccinated, and this further complicates coverage determination and, by extrapolation, immunity estimation. Use of incomplete or inaccurate surveillance data is a major hurdle to calculating population immunity derived from wild virus infection [2].

The World Health Organization (WHO) Western Pacific Region (WPR) has maintained its polio-free status since 2000. The emergence of vaccine-derived polioviruses (VDPVs), however, remains a risk, as oral polio vaccine (OPV) is still used in many of the region's countries, and pockets of unimmunized or underimmunized children exist in some countries. From 2014 to 2016, the region participated in the globally coordinated efforts to introduce inactivated polio vaccine (IPV) into all countries that did not yet include it in their national immunization schedules, and to "switch" from trivalent OPV (tOPV) to bivalent OPV (bOPV) in all countries still using OPV in 2016. As of September 2016, 15 of 17 countries and areas that did not use IPV by the end of 2014 had introduced IPV. Introduction in the remaining 2 countries has been delayed because of the global shortage of IPV, making it unavailable to select lower-risk countries until the fourth quarter of 2017. All 16 countries using OPV as of 2016 successfully withdrew tOPV during the globally synchronized switch from April to May 2016, and 15 of 16 countries introduced bOPV at the same time, with the remaining country introducing it within 30 days. While countries were primarily responsible for self-funding these activities, additional support was provided. The main challenges encountered in the Western Pacific Region with both IPV introduction and the tOPV-bOPV switch were related to overcoming regulatory policies and challenges with vaccine procurement. As a result, substantial lead time was needed to resolve procurement and regulatory issues before the introductions of IPV and bOPV. As the global community prepares for the full removal of all OPV from immunization programs, this need for lead time and consideration of the impact on national policies should be considered.

Background. The potential to strengthen routine immunization (RI) services through supplementary immunization activities (SIAs) is an important benefit of global measles and rubella elimination and polio eradication strategies. However, little evidence exists on how best to use SIAs to strengthen RI. As part the 2012 Nepal measles-rubella and polio SIA, we developed an intervention package designed to improve RI processes and evaluated its effect on specific RI process measures. Methods. The intervention package was incorporated into existing SIA activities and materials to improve healthcare providers' RI knowledge and practices throughout Nepal. In 1 region (Central Region) we surveyed the same 100 randomly selected health facilities before and after the SIA and evaluated the following RI process measures: vaccine safety, RI planning, RI service delivery, vaccine supply chain, and RI data recording practices. Data collection included observations of vaccination sessions, interviews with the primary healthcare provider who administered vaccines at each facility, and administrative record reviews. Pair-matched analytical methods were used to determine whether statistically significant changes in the selected RI process measures occurred over time. Results. After the SIA, significant positive changes were measured in healthcare provider knowledge of adverse events following immunization (11% increase), availability of RI microplans (+17%) and maps (+12%), and awareness of how long a reconstituted measles vial can be used before it must be discarded (+14%). For the SIA, 42% of providers created an SIA high-risk villages list, and >50% incorporated this information into RI outreach session site planning. Significant negative changes occurred in correct knowledge of measles vaccination contraindications ( -11%), correct definition for a measles outbreak ( -21%), and how to treat a child with a severe adverse event following immunization ( -10%). Twenty percent of providers reported cancelling >=1 RI sessions during the SIA. Many RI process measures were at high proportions (>90%) before the SIA and remained high afterward, including proper vaccine administration techniques, proper vaccine waste management, and availability of vaccine carriers and vaccine registers. Conclusions. Focusing on activities that are easily linked between SIAs and RI services, such as using SIA high-risk village list to strengthen RI microplanning and examining ways to minimize the impact of an SIA on RI session scheduling, should be prioritized when implementing SIAs.

BACKGROUND: A globally-coordinated phase out of all type 2 containing oral polio vaccine (OPV) is planned for April 2016 during which bivalent 1+3 OPV (bOPV) will replace trivalent OPV (tOPV) in routine immunization schedules and campaigns. Diarrhea impairs the immune response to tOPV, but the effect of diarrhea on bOPV is unknown. METHODS: Infants aged 6 weeks to 11 months, who had received <3 doses of OPV and had mild-moderate diarrhea or no diarrhea, were recruited at five health facilities in Nepal. Neutralizing antibody titers to poliovirus types 1 and 3 were measured before and 28 days after bOPV administration. The effect of diarrhea and other factors on seroconversion or boosting in antibody titers to poliovirus was assessed by multivariable analysis. RESULTS: Infants with diarrhea, versus those without diarrhea, had reduced response for poliovirus types 1 (56% [87/156] vs 66% [109/164]) and 3 (34% [70/209] vs 52% [122/236]). After adjusting for other factors, infants with diarrhea had significantly reduced response for type 3 (odds ratio [OR]=0.44, 95% CI 0.29-0.68), as did infants with >5 loose stools per day (OR=0.36, 95% CI 0.21-0.62). CONCLUSIONS: Diarrhea reduced the immune response to bOPV. Provision of additional doses of polio vaccine is necessary to maintain high population immunity in areas with high prevalence of diarrheal disease. CLINICAL TRIAL REGISTRY: This study is registered at clinicaltrials.gov as NCT01559636.

In 2012, the World Health Organization Regional Committee for the Western Pacific Region (WPR) reaffirmed its commitment to eliminate measles and urged WPR member states to interrupt endemic measles virus transmission as rapidly as possible. In 2013, a large measles outbreak occurred in the Philippines despite implementation of measles elimination strategies including a nationwide supplemental immunization activity (SIA) in 2011 using measles- and rubella-containing vaccine and targeting children aged nine months to seven years. To prevent future measles outbreaks a new tool was developed to assess district-level risk for measles outbreaks, based on the WPR polio risk assessment tool previously applied in the Philippines. Risk was assessed as a function of combined indicator scores from four data input categories: population immunity, surveillance quality, program performance, and threat assessment. On the basis of the overall score, the tool assigned each district a risk category of low, medium, high, or very high. Of the 122 districts and highly urbanized cities in the Philippines, 58 (48%) were classified as high risk or very high risk, including the district of the Metro Manila area and Region 4A where the outbreak began in 2013. Risk assessment results were used to guide the monitoring and supervision during the nationwide SIA conducted in 2014. The initial tool drafted in the Philippines served as a template for development of the global risk assessment tool. Regular annual measles programmatic risk assessments can be used to help plan risk mitigation activities and measure progress toward measles elimination.

All six World Health Organization (WHO) regions have now set goals for measles elimination by or before 2020. To prioritize measles elimination efforts and use available resources efficiently, there is a need to identify at-risk areas that are offtrack from meeting performance targets and require strengthening of programmatic efforts. This article describes the development of a WHO measles programmatic risk assessment tool to be used for monitoring, guiding, and sustaining measles elimination efforts at the subnational level. We outline the tool development process; the tool specifications and requirements for data inputs; the framework of risk categories, indicators, and scoring; and the risk category assignment. Overall risk was assessed as a function of indicator scores that fall into four main categories: population immunity, surveillance quality, program performance, and threat assessment. On the basis of the overall score, the tool assigns each district a risk of either low, medium, high, or very high. The cut-off criteria for the risk assignment categories were based on the distribution of scores from all possible combinations of individual indicator cutoffs. The results may be used for advocacy to communicate risk to policymakers, mobilize resources for corrective actions, manage population immunity, and prioritize programmatic activities. Ongoing evaluation of indicators will be needed to evaluate programmatic performance and plan risk mitigation activities effectively. The availability of a comprehensive tool that can identify at-risk districts will enhance efforts to prioritize resources and implement strategies for achieving the Global Vaccine Action Plan goals for measles elimination.

In 2005, the Regional Committee for the World Health Organization (WHO) Western Pacific Region (WPR) established a goal to eliminate measles by 2012.The recommended elimination strategies in WPR include 1) ≥95% 2-dose coverage with measles-containing vaccine (MCV) through routine immunization services and supplementary immunization activities (SIAs)dagger; 2) high-quality case-based measles surveillance; 3) laboratory surveillance with timely and accurate testing of specimens to confirm or discard suspected cases and detect measles virus genotypes; and 4) measles outbreak preparedness, rapid response, and appropriate case management. In the WPR, the Philippines set a national goal in 1998 to eliminate measles by 2008. This report describes progress toward measles elimination in the Philippines during 1998-2014 and challenges remaining to achieve the goal. WHO-United Nations Children's Fund (UNICEF)-estimated coverage with the routine first dose of MCV (MCV1) increased from 80% in 1998 to 90% in 2013, and coverage with the routine second dose of MCV (MCV2) increased from 10% after nationwide introduction in 2010 to 53% in 2013. After nationwide SIAs in 1998 and 2004, historic lows in the numbers and incidence of reported measles cases occurred in 2006. Despite nationwide SIAs in 2007 and 2011, the number of reported cases and incidence generally increased during 2007-2012, and large measles outbreaks occurred during 2013-2014 that affected infants, young children, older children, and young adults and that were prolonged by delayed and geographically limited outbreak response immunization activities during 2013-2014. For the goal of measles elimination in WPR to be achieved, sustained investments are required in the Philippines to strengthen health systems, implement the recommended elimination strategies, and develop additional strategies to identify and reduce measles susceptibility in specific geographic areas and older age groups.

BACKGROUND: In Nepal, an estimated 2-4% of the population has chronic hepatitis B virus (HBV) infection. To combat this problem, from 2002 to 2004, a national three dose hepatitis B vaccination program was implemented to decrease infection rates among children. The program does not currently include a birth dose to prevent perinatal HBV transmission. In 2012, to assess the impact of the program, we conducted a serosurvey among children born before and after vaccine introduction. METHODS: In 2012, a cross-sectional nationally representative stratified cluster survey was conducted to estimate hepatitis B surface antigen (HBsAg) prevalence among children born from 2006 to 2007 (post-vaccine cohort) and among children born from 2000 to 2002 (pre-vaccine cohort). Demographic data, as well as written and oral vaccination history were collected. All children were tested for HBsAg; mothers of HBsAg positive children were also tested. Furthermore, we evaluated the field sensitivity and specificity of the SD Bioline HBsAg rapid diagnostic test by comparing results with an enzyme immunoassay. RESULTS: Among 2181 post-vaccination cohort children with vaccination data by either card or recall, 86% (95% confidence interval [CI] 77-95%) received ≥3 hepatitis B vaccine doses. Of 1200 children born in the pre-vaccination cohort, 0.28% (95% CI 0.09-0.85%) were positive for HBsAg; of 2187 children born in the post-vaccination cohort, 0.13% (95% CI 0.04-0.39%) were positive for HBsAg (p=0.39). Of the six children who tested positive for HBsAg, two had mothers who were positive for HBsAg. Finally, we found the SD Bioline HBsAg rapid diagnostic test to have a sensitivity of 100% and a specificity of 100%. CONCLUSIONS: This is the first nationally representative hepatitis B serosurvey conducted in Nepal. Overall, a low burden of chronic HBV infection was found in children born in both the pre and post-vaccination cohorts. Current vaccination strategies should be continued.

Wider availability of the live, attenuated SA 14-14-2 Japanese encephalitis (JE) vaccine has facilitated introduction or expansion of immunization programs in many countries. However, information on their impact is limited. In 2006, Nepal launched a JE immunization program, and by 2009, mass campaigns had been implemented in 23 districts. To describe the impact, we analyzed surveillance data from 2004 to 2009 on laboratory-confirmed JE and clinical acute encephalitis syndrome (AES) cases. The post-campaign JE incidence rate of 1.3 per 100,000 population was 72% lower than expected if no campaigns had occurred, and an estimated 891 JE cases were prevented. In addition, AES incidence was 58% lower, with an estimated 2,787 AES cases prevented, suggesting that three times as many disease cases may have been prevented than indicated by the laboratory-confirmed JE cases alone. These results provide useful information on preventable JE disease burden and the potential value of JE immunization programs.