Seroprevalence and predictors of Hepatitis A virus immunity among young MSM in urban Brazil: a cross-sectional study at a referral center

In addition, the usual socioeconomic and sanitary exposures to Hepatitis A Virus (HAV), men who have sex with men (MSM) are also exposed through sexual behavior. ObjectiveThis research aims to estimate the HAV seroprevalence and its predictors among young MSM. MethodsThis cross-sectional study, conducted in Rio de Janeiro/Brazil, included participants sequentially between 2019 and 2022. Inclusion criteria were cisgender males aged 18 to 35 who reported sex with men in the previous six months, had never received the HAV vaccine, and had no chronic immune-mediated conditions. Predictors represented sexual practices, use of different substances, sexually transmitted infections, signs or symptoms, water consumption and sanitation, and socio-demographic. The outcome of all the analyses was HAV serology (positive vs. negative). The main analysis compared the prediction performances of the random forest regression model with penalized GLM with internal cross-validation or bootstrap. ResultsThe HAV seroprevalence was 39.6%. The compared models included from 16 to 42 predictors, always representing all predictor dimensions. "Chemsex" was identified as a predictor of HAV seroprevalence. A generation effect, interactions among race, education, and source of income were also identified as HAV predictors. The best model had excellent calibration and a moderate discrimination with an area under the ROC curve of 0.714 and an R2 of 0.187. We provide a web calculator at https://pedrobrasil.shinyapps.io/INDWELL/. ConclusionThis study reveals a high susceptibility of cisgender young MSM to HAV infection. These findings highlight the enduring impact of socioeconomic inequities on enteric virus exposure and underscore the need for targeted public health strategies. One may use the prediction model to estimate the risk of seropositivity/susceptibility to HAV in aid of deciding either to perform a HAV test or to vaccinate against HAV, or even to estimate HAV seroprevalence in MSM populations where the HAV test is not easily available. HIGHLIGHTSO_LIThe susceptibility to Hepatitis A infection among men who have sex with men (MSM) in Rio de Janeiro is approximately 60%. C_LIO_LIUsual exposures to Hepatitis A, such as socio-economic, sanitary, and the generation effect, are linked to Hepatitis A seroprevalence similarly in the MSM population. C_LIO_LIIn addition to the traditional exposures to Hepatitis A virus, there is evidence linking directly sexual behaviors and preferences, and use of drugs to engaging in sex ("chemsex") to Hepatitis A seropositivity. C_LIO_LIWe developed an instrument to predict Hepatitis A seropositivity among men who have sex with men with good performance. C_LI ETHICS STATEMENTAll procedures were performed in compliance with the good clinical practice document of the Americas (PAHO) and the Brazilian national Resolution n{degrees} 510/2016 and Resolution n{degrees} 466/2012 from the National Health Council (Conselho Nacional de Saude - CNS). The institutional Ethics Committee (Instituto Nacional de Infectologia Evandro Chagas - Fundacao Oswaldo Cruz) approved this research on March 22nd, 2018, with the number CAAE 80901917.0.0000.5262 (accessible at https://plataformabrasil.saude.gov.br/login.jsf). All participants gave written informed consent, and the privacy rights of human subjects were always observed.