Last data update: Oct 28, 2024. (Total: 48004 publications since 2009)
Records 1-9 (of 9 Records) |
Query Trace: Pollock ED[original query] |
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Modelling the impact of vaccination and sexual behaviour adaptations on mpox cases in the USA during the 2022 outbreak
Clay PA , Asher JM , Carnes N , Copen CE , Delaney KP , Payne DC , Pollock ED , Mermin J , Nakazawa Y , Still W , Mangla AT , Spicknall IH . Sex Transm Infect 2023 BACKGROUND: The 2022 mpox outbreak has infected over 30 000 people in the USA, with cases declining since mid-August. Infections were commonly associated with sexual contact between men. Interventions to mitigate the outbreak included vaccination and a reduction in sexual partnerships. Understanding the contributions of these interventions to decreasing cases can inform future public health efforts. METHODS: We fit a dynamic network transmission model to mpox cases reported by Washington DC through 10 January 2023. This model incorporated both vaccine administration data and reported reductions in sexual partner acquisition by gay, bisexual or other men who have sex with men (MSM). The model output consisted of daily cases over time with or without vaccination and/or behavioural adaptation. RESULTS: We found that initial declines in cases were likely caused by behavioural adaptations. One year into the outbreak, vaccination and behavioural adaptation together prevented an estimated 84% (IQR 67% to 91%) of cases. Vaccination alone averted 79% (IQR 64% to 88%) of cases and behavioural adaptation alone averted 25% (IQR 10% to 42%) of cases. We further found that in the absence of vaccination, behavioural adaptation would have reduced the number of cases, but would have prolonged the outbreak. CONCLUSIONS: We found that initial declines in cases were likely caused by behavioural adaptation, but vaccination averted more cases overall and was key to hastening outbreak conclusion. Overall, this indicates that outreach to encourage individuals to protect themselves from infection was vital in the early stages of the mpox outbreak, but that combination with a robust vaccination programme hastened outbreak conclusion. |
Using infection prevalence, seroprevalence and case report data to estimate chlamydial infection incidence
Clay PA , Pollock ED , Copen CE , Anyalechi GE , Danavall DC , Hong J , Khosropour CM , Galloway E , Spicknall IH . Sex Transm Infect 2023 99 (8) 513-519 OBJECTIVES: To measure the effectiveness of chlamydia control strategies, we must estimate infection incidence over time. Available data, including survey-based infection prevalence and case reports, have limitations as proxies for infection incidence. We therefore developed a novel method for estimating chlamydial incidence. METHODS: We linked a susceptible infectious mathematical model to serodynamics data from the National Health and Nutritional Examination Survey, as well as to annual case reports. We created four iterations of this model, varying assumptions about how the method of infection clearance (via treatment seeking, routine screening or natural clearance) relates to long-term seropositivity. Using these models, we estimated annual infection incidence for women aged 18-24 and 25-37 years in 2014. To assess model plausibility, we also estimated natural clearance for the same groups. RESULTS: Of the four models we analysed, the model that best explained the empirical data was the one in which longer-lasting infections, natural clearance and symptomatic infections all increased the probability of long-term seroconversion. Using this model, we estimated 5910 (quartile (Q)1, 5330; Q3, 6500) incident infections per 100 000 women aged 18-24 years and 2790 (Q1, 2500; Q3, 3090) incident infections per 100 000 women aged 25-37 years in 2014. Furthermore, we estimated that natural clearance rates increased with age. CONCLUSIONS: Our method can be used to estimate the number of chlamydia infections each year, and thus whether infection incidence increases or decreases over time and after policy changes. Furthermore, our results suggest that clearance via medical intervention may lead to short-term or no seroconversion, and the duration of untreated chlamydial infection may vary with age, underlining the complexity of chlamydial infection dynamics. |
Modelling the impact of vaccination and sexual behavior change on reported cases of mpox in Washington D.C (preprint)
Clay PA , Asher JM , Carnes N , Copen CE , Delaney KP , Payne DC , Pollock ED , Mermin J , Nakazawa Y , Still W , Mangla AT , Spicknall IH . medRxiv 2023 14 Background: The 2022 mpox outbreak infected over 30,000 people in the United States. Infections were commonly associated with sexual contact between men. Interventions included vaccination and reductions in sexual partnerships. We estimated the averted infections attributable to each intervention using mathematical modeling. Method(s): We fit a dynamic network transmission model to mpox cases reported by the District of Columbia through January 2023. We incorporated vaccine administration data and reported reductions in sexual partnerships among gay, bisexual, or other men who have sex with men (MSM). Model output consisted of predicted cases over time with or without vaccination and/or behavior change. Result(s): We estimated initial case reductions were due to behavior change. Vaccination alone averted 64% [IQR:57%-72%] and behavior change alone averted 21% [IQR:11%-29%] of cases. Vaccination and behavior change together averted 80% [IQR:74%-85%] of cases. In the absence of vaccination, behavior change reduced cumulative cases but also prolonged the outbreak. Conclusion(s): Initial case declines were likely caused by behavior change, but vaccination averted more cases overall. Overall, this indicates that encouraging individuals to protect themselves was vital in the early outbreak, but that combination with a robust vaccination program was ultimately required for control. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available for use under a CC0 license. |
Potential for recurrent mpox outbreaks among gay, bisexual, and other men who have sex with men - United States, 2023
Pollock ED , Clay PA , Keen A , Currie DW , Carter RJ , Quilter LAS , Gundlapalli AV , Mermin J , Spicknall IH . MMWR Morb Mortal Wkly Rep 2023 72 (21) 568-573 More than 30,000 monkeypox (mpox) cases have been diagnosed in the United States since May 2022, primarily among gay, bisexual, and other men who have sex with men (MSM) (1,2). In recent months, diagnoses have declined to one case per day on average. However, mpox vaccination coverage varies regionally, suggesting variable potential risk for mpox outbreak recurrence (3). CDC simulated dynamic network models representing sexual behavior among MSM to estimate the risk for and potential size of recurrent mpox outbreaks at the jurisdiction level for 2023 and to evaluate the benefits of vaccination for preparedness against mpox reintroduction. The risk for outbreak recurrence after mpox reintroduction is linearly (inversely) related to the proportion of MSM who have some form of protective immunity: the higher the population prevalence of immunity (from vaccination or natural infection), the lower the likelihood of recurrence in that jurisdiction across all immunity levels modeled. In contrast, the size of a potential recurrent outbreak might have thresholds: very small recurrences are predicted for jurisdictions with mpox immunity of 50%-100%; exponentially increasing sizes of recurrences are predicted for jurisdictions with 25%-50% immunity; and linearly increasing sizes of recurrences are predicted for jurisdictions with <25% immunity. Among the 50 jurisdictions examined, 15 are predicted to be at minimal risk for recurrence because of their high levels of population immunity. This analysis underscores the ongoing need for accessible and sustained mpox vaccination to decrease the risk for and potential size of future mpox recurrences. |
Estimated Incidence and Prevalence of Gonorrhea in the United States, 2006-2019.
Pollock ED , Clay PA , Kreisel KM , Spicknall IH . Sex Transm Dis 2023 50 (4) 188-195 BACKGROUND: We extend recent work estimating incidence and prevalence of gonococcal infections among men and women aged 15-39 years in the US in 2018 by applying the same modeling framework to estimate gonococcal incidence and prevalence during 2006-2019. METHODS: The model is informed by cases from the Nationally Notifiable Disease Surveillance System, data from the National Survey of Family Growth, and data on other factors known to impact gonococcal incidence and prevalence. We use Monte Carlo simulation to account for uncertainty in input parameters. Results are reported as median annual per-capita incidence and prevalence; uncertainty intervals are characterized by the 25th and 75th simulated percentiles. RESULTS: 1,603,473 (1,467,801-1,767,779) incident cases of gonorrhea were estimated in 2019. Per-capita incidence increased 32%, from 1101 (1002-1221) to 1456 (1333-1605) infections per 100,000 persons. This trend in per-capita incidence had three phrases: an initial decline during 2006-2009, a plateau through 2013, and a rapid increase of 66% through 2019. Men aged 25-39 experienced the greatest increase in incidence (125%, 541 (467-651) to 1212 infections (1046-1458) per 100,000 men). Women aged 25-39 had the lowest incidence in 2019, with 1040 infections (882-1241) per 100,000 women. Prevalence increased more slowly among those aged 25-39 vs. 15-24. The incidence ratio comparing men to women aged 25-39 increased from 0.76 to 1.18. CONCLUSIONS: The burden of gonorrhea has increased among men and women aged 15-39 years since 2013. An increasing proportion of incident infections are among men. Additional biomedical and behavioral interventions are needed to control gonococcal transmission. |
Modeling the impact of sexual networks in the transmission of monkeypox virus among gay, bisexual, and other men who have sex with men - United States, 2022
Spicknall IH , Pollock ED , Clay PA , Oster AM , Charniga K , Masters N , Nakazawa YJ , Rainisch G , Gundlapalli AV , Gift TL . MMWR Morb Mortal Wkly Rep 2022 71 (35) 1131-1135 What is already known about this topic? The 2022 monkeypox outbreak is associated with sexual and intimate contact. Survey data suggest that gay, bisexual, and other men who have sex with men (MSM), who have been disproportionately affected, are reducing one-time partnerships. What is added by this report? Modeling of sexual infection transmission between men indicates that one-time partnerships, which account for 3% of daily sexual partnerships and 16% of daily sex acts, account for approximately 50% of daily Monkeypox virus (MPXV) transmission. A 40% reduction in one-time partnerships might delay the spread of monkeypox and reduce the percentage of persons infected by 20% to 31%. What are the implications for public health practice? Reductions in one-time partnerships, already being reported by MSM, might significantly reduce MPXV transmission. © 2022 Department of Health and Human Services. All rights reserved. |
Declines in pregnancies among US adolescents from 2007 to 2017: Behavioral contributors to the trend
Goodreau SM , Pollock ED , Wang LY , Li J , Aslam MV , Katz DA , Hamilton DT , Rosenberg ES . J Pediatr Adolesc Gynecol 2022 35 (6) 676-684 STUDY OBJECTIVES: Adolescents in the United States have undergone dramatic declines in pregnancies and births in recent decades. We aimed to estimate the contribution of changes in three proximal behaviors to these declines among 14-18-year-olds for 2007-2017: 1) delays in age at first sexual intercourse, 2) declines in number of sexual partners, and 3) changes in contraceptive use, particularly uptake of long-acting reversible contraception (LARC). DESIGN: We adapted an existing iterative dynamic population model and parameterized it using six waves of the Centers for Disease Control and Prevention's Youth Risk Behavior Survey. We compared pregnancies from observed behavioral trends with counterfactual scenarios that assumed constant behaviors over the decade. We calculated outcomes by cause, year and age. RESULTS: We found that changes in these behaviors could explain reductions of 496,200, 78,500, and 40,700 pregnancies over the decade, respectively, with total medical and societal cost savings of $9.71 billion, $1.54 billion, and $796 million. LARC adoption, particularly among 18-year-olds, could explain much of the improvements from contraception use. The three factors together did not fully explain observed birth declines; adding a 50% decline in sex acts per partner did. CONCLUSIONS: Delays in first sexual intercourse contributed the most to declining births over this decade, although all behaviors considered had major effects. Differences from earlier models may result from differences in years and ages covered. Evidence-based teen pregnancy prevention programs, including comprehensive sex education, youth-friendly reproductive health services and parental and community support can continue to address these drivers and reduce teen pregnancy. |
Impacts of changing sexual behavior on chlamydia and gonorrhea burden among US high school students, 2007-2017
Goodreau SM , Pollock ED , Wang LY , Aslam MV , Barrios LC , Dunville RL , Rosenthal EM , Hamilton DT , Katz DA , Rosenberg ES . Sex Transm Dis 2021 48 (9) 635-642 BACKGROUND: Rates of adolescent sexual activity have long been declining in the United States. We sought to estimate the number of cases of gonorrhea and chlamydia averted over one decade associated with these declines, and associated costs saved. METHODS: We analyzed data from the CDC's Youth Risk Behavior Survey of US high-school students from 2007-2017 and combined it with epidemiological estimates drawn from the literature to parameterize a dynamic population transmission model. We compared transmissions from observed behavioral trends to a counterfactual scenario that assumed sexual behaviors from 2007 remained constant over 10 years. We calculated outcomes by age and for three racial/ethnic groups (Hispanic, non-Hispanic Black, and non-Hispanic White adolescents) who vary on underlying burden and amount of behavioral change. RESULTS: We estimated 1,118,483 cases of chlamydia and 214,762 cases of gonorrhea were averted (19.5% of burden across all ages). This yielded $474 million (2017 dollars) savings in medical costs over the decade. The largest number of averted cases (767,543) was among Black adolescents, but the largest proportion (28.7%) was among Hispanic adolescents. CONCLUSIONS: Whatever its origins, changing sexual behavior among adolescents results in large estimated reductions in STI burden and medical costs relative to previous cohorts. Although diagnoses among adolescents have not declined at this rate, multiple explanations could make these apparently divergent trends consistent. Efforts to continue supporting effective sex education in and out of school along with STI screening for adolescents should reinforce these gains. |
Predicting the impact of sexual behavior change on adolescent STI in the US and New York State: a case study of the teen-SPARC tool
Goodreau SM , Pollock ED , Wang LY , Barrios LC , Dunville RL , Aslam MV , Katz DA , Hart-Malloy R , Rosenthal EM , Trigg M , Fields M , Hamilton DT , Rosenberg ES . Ann Epidemiol 2020 47 13-18 Purpose: Adolescents aged 13–18 years bear a large burden of sexually transmitted infections (STIs) and changing adolescent sexual risk behavior is a key component of reducing this burden. We demonstrate a novel publicly available modeling tool (teen-SPARC) to help state and local health departments predict the impact of behavioral change on gonorrhea, chlamydia, and HIV burden among adolescents. Methods: Teen-SPARC is built in Excel for familiarity and ease and parameterized using data from CDC's Youth Risk Behavior Surveillance System. We present teen-SPARC's methods, including derivation of national parameters and instructions to obtain local parameters. We model multiple scenarios of increasing condom use and estimate the impact on gonorrhea, chlamydia, and HIV incidence, comparing national and New York State (NYS) results. Results: A 1% annual increase in condom use (consistent with Healthy People 2020 goals) could prevent nearly 10,000 cases of STIs nationwide. Increases in condom use of 17.1%, 2.2%, and 25.5% in NYS would be necessary to avert 1000 cases of gonorrhea, 1000 cases of chlamydia, and 10 cases of HIV infection, respectively. Additional results disaggregate outcomes by age, sex, partner sex, jurisdiction, and pathogen. Conclusion: Teen-SPARC may be able to assist health departments aiming to tailor behavioral interventions for STI prevention among adolescents. |
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