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Background/Objectives: Enzyme-linked immunosorbent assays (ELISAs) have been used to measure anti-human-papillomavirus (HPV) immunoglobulin IgG. The goal of this study was to evaluate the reproducibility of ELISAs measuring different HPV immunoglobulin isotypes, IgG1, 2, 3, and 4, IgA, and IgM, against HPV16. Methods: Seventy-two serum samples collected from participants in the Costa Rica HPV Vaccine Trial (CVT) and immunized with bivalent HPV vaccine (2vHPV) were used for reproducibility assessment. IgG2 and IgG4 levels were too low to be detected. Levels of IgG1, IgG3, IgA, and IgM were measured, and the data were used to calculate intraclass correlation coefficients (ICCs) and coefficients of variation (CVs). Results: CVs were assessed between technicians (12.8–22.7%) and across days (6.2–30.6%). The overall CVs ranged from 7.7–31.1%. IgM ELISA showed higher CVs (15.8–31.1%) than IgG1, IgG3, and IgA (6.2–22.7%). All ICC values were >98.7%. IgG3 was detected in all samples, while IgG1 and IgA had >86.3% detectability and IgM had 62.1% detectability. Pearson correlational analyses between different antibodies all showed significant correlations (p ≤ 0.001), except when comparing IgGs or IgA to IgM (p = 0.29–0.53). Conclusions: Our data showed that these ELISAs are reproducible and detect isotype antibodies to HPV16 L1 across a range of concentrations in 2vHPV-vaccinated participants.

Summary: Background: The true incidence of SARS-CoV-2 infection in Costa Rica was likely much higher than officially reported, because infection is often associated with mild symptoms and testing was limited by official guidelines and socio-economic factors. Methods: Using serology to define natural infection, we developed a statistical model to estimate the true cumulative incidence of SARS-CoV-2 in Costa Rica early in the pandemic. We estimated seroprevalence from 2223 blood samples collected from November 2020 to October 2021 from 1976 population-based controls from the RESPIRA study. Samples were tested for antibodies against SARS-CoV-2 nucleocapsid and the receptor-binding-domain of the spike proteins. Using a generalized linear model, we estimated the ratio of true infections to officially reported cases. Applying these ratios to officially reported totals by age, sex, and geographic area, we estimated the true number of infections in the study area, where 70% of Costa Ricans reside. We adjusted the seroprevalence estimates for antibody decay over time, estimated from 1562 blood samples from 996 PCR-confirmed COVID-19 cases. Findings: The estimated total proportion infected (ETPI) was 4.0 times higher than the officially reported total proportion infected (OTPI). By December 16th, 2021, the ETPI was 47% [42–52] while the OTPI was 12%. In children and adolescents, the ETPI was 11.0 times higher than the OTPI. Interpretation: Our findings suggest that nearly half the population had been infected by the end of 2021. By the end of 2022, it is likely that a large majority of the population had been infected. Funding: This work was sponsored and funded by the National Institute of Allergy and Infectious Diseases through the National Cancer Institute, the Science, Innovation, Technology and Telecommunications Ministry of Costa Rica, and Costa Rican Biomedical Research Agency-Fundacion INCIENSA (grant N/A).

Objective. To describe the rationale and the method­ology of a multicenter project to study the etiology of breast cancer in young Latin American women. Materials and methods. The International Agency for Research on Cancer has established an international collaborative population-based case-control study in four countries in Latin America: Chile, Colombia, Costa Rica, and Mexico (the PRECAMA study). Standardized methodologies were developed to collect information on reproductive variables, lifestyle, anthropometry, diet, clinical and pathological data, and biological specimens. The study will be extended to other countries in the region. Conclusion. PRECAMA is unique in its multidisciplinary approach that combines genet­ics, genomics, and metabolomics with lifestyle factors. The data generated through this project will be instrumental to identify major risk factors for molecular subtypes of breast cancer in young women, which will be important for pre­vention and targeted screening programs in Latin America.