High-quality, representative serological surveys allow direct estimates of immunity profiles to inform vaccination strategies but can be costly and logistically challenging. Leveraging residual serum samples is one way to increase their feasibility. We subsampled 9854 residual sera from a 2016 national HIV survey in Zambia and tested these specimens for anti-measles and anti-rubella virus IgG antibodies using indirect enzyme immunoassays. We demonstrate innovative methods for sampling residual sera and analyzing seroprevalence data, as well as the value of seroprevalence estimates to understand and control measles and rubella. National measles and rubella seroprevalence for individuals younger than 50 years was 82.8% (95% CI 81.6, 83.9%) and 74.9% (95% CI 73.7, 76.0%), respectively. Despite a successful childhood vaccination program, measles immunity gaps persisted across age groups and districts, indicating the need for additional activities to complement routine immunization. Prior to vaccine introduction, we estimated a rubella burden of 96 congenital rubella syndrome cases per 100,000 live births. Residual samples from large-scale surveys can reduce the cost and challenges of conducting serosurveys, and multiple pathogens can be tested. Procedures to access quality specimens, ensure ethical approvals, and link sociodemographic data can improve the timeliness and value of results.

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Author summary The use of biomarkers to measure immune responses in serum is crucial for understanding population-level exposure and susceptibility to human pathogens. Advances in sample collection, multiplex testing, and computational modeling are transforming serosurveillance into a powerful tool for public health program design and response to infectious threats. In July 2018, 70 scientists from 16 countries met to perform a landscape analysis of approaches that support an integrated serosurveillance platform, including the consideration of issues for successful implementation. Here, we summarize the group’s insights and proposed roadmap for implementation, including objectives, technical requirements, ethical issues, logistical considerations, and monitoring and evaluation.

Introduction: This study estimates the annual population-level impact of 13-valent pneumococcal conjugate vaccine (PCV13) infant national immunization programs (NIPs) on vaccine-type and non-vaccine type invasive pneumococcal disease (IPD) incidence across all ages using national surveillance data. Methods: We identified countries (Australia, Canada, England and Wales, Israel, and the US) with national IPD active surveillance data that introduced the seven-valent PCV (PCV7) followed by PCV13, which also reported annual serotype-and age group-specific incidence. We extracted IPD incidence by serotype groupings [PCV13 minus PCV7 (PCV13-7) serotypes;

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Background After a decade of 13-valent pneumococcal conjugate vaccine (PCV13) use in children, many observational studies have evaluated PCV13 vaccine effectiveness (VE) in various epidemiologic and geographic settings. The objective of this study was to systematically review the global evidence on VE of PCV13 against IPD in children. Methods A systematic literature review using Cochrane methods was conducted in November 2021 to evaluate PCV13 VE against vaccine-type and serotype-specific IPD in children. A search of Medline, Embase, the Cochrane Library (CENTRAL and CDSR), and 5 key conferences (2019-2021) was conducted, and eligible English-language articles were abstracted. Results 15 studies on PCV13 VE were included, primarily from Europe (n=7) and North America (n=3) as well as Africa (n=2), Australasia (n=2), and Asia (n=1). 11 reported VE in children who completed the full vaccination schedule [3+1 (n=3), 2+1 (n=4), 3+0 (n=3), and mixed 3+1 or 2+1 schedules (n=1)] (Table 1). 4 studies did not report VE after the complete vaccination schedule. 8 studies reported PCV13-type VE, 3 reported PCV7-type VE, and 6 reported PCV13 non-PCV7 VE. PCV13-type VE was 90 and 91% in studies using a 3+1 schedule (n=2), 76% and 79% in studies using a 2+1 schedule (n=2) and ranged from 59% to 94% in a 3+0 schedule (n=3), with variability by study design and age range (Table 1). One study reported 100% PCV13-type VE in Spain where mixed 3+1 and 2+1 schedules were used. All PCV13-type VE results were statistically significant except two outcomes restricted to children 12-24 month of age from a single study in Australia. High VE was reported against PCV13 non-PCV7 serotype IPD for fully vaccinated children across all schedules, ranging from 60% to 100% (n=6). PCV13 was effective against the shared PCV7 serotypes, ranging from 75% to 83% (n=3). Conclusion Children fully vaccinated with PCV13 have a high level of direct protection against vaccine-type IPD, irrespective of geographic variation. PCV13 VE against the shared PCV7 serotypes remained high and PCV13 VE was also high for the 6 additional PCV13-non PCV7 serotypes. PCV13 VE tended to be higher in 3+1 schedules and additional analyses by dosing schedule are needed. Disclosures Johnna Perdrizet, MPH, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Iwona Pustulka, MSc, Pfizer Inc.: I'm an employee of Evidera who have been paid by Pfizer Inc. to conduct an SLR which results are presented in the abstract Carol A. Forbes, PhD, Evidera (part of Thermo Fisher Scientific): Employee|Pfizer Inc: I am an employee of Evidera (part of Thermo Fisher Scientific)who have been paid by Pfizer Inc. to carry out the work reported in this abstract|Thermo Fisher Scientific: Stocks/Bonds Emily Horn, MSc, Pfizer Inc: Employee Bradford J. Gessner, M.D., M.P.H., Pfizer Inc.: Employee|Pfizer Inc.: Stocks/Bonds Kyla hayford, PhD, Pfizer Vaccines: Employed|Pfizer Vaccines: Stocks/Bonds.