Seroprevalence of IgG and IgM anti-SARS-CoV-2 among voluntary blood donors in Rio de Janeiro, Brazil

Luiz Amorim Filho; Célia Landmann Szwarcwald; Sheila de Oliveira Garcia Mateos; Antonio Carlos Monteiro Ponce de Leon; Roberto de Andrade Medronho; Valdiléa Gonçalves Veloso; Josiane Iole França Lopes; Luis Cristovão de Moraes Sobrino Porto; Alexandre Chieppe; Guilherme Loureiro Werneck

doi:10.1590/SciELOPreprints.404

##article.authors##

Luiz Amorim Filho Hemorio. Estado do Rio de Janeiro, Brasil https://orcid.org/0000-0002-7714-3531
Célia Landmann Szwarcwald Fundação Instituto Oswaldo Cruz, Instituto de Comunicação e Informação Científica e Tecnológica em Saúde. Rio de Janeiro, Brasil
Sheila de Oliveira Garcia Mateos Hemorio, Estado do Rio de Janeiro, Brasil e Universidade de São Paulo, Faculdade de Medicina da Universidade de São Paulo, Brasil
Antonio Carlos Monteiro Ponce de Leon Universidade do Estado do Rio de Janeiro, Instituto de Medicina Social. Rio de Janeiro, Brasil
Roberto de Andrade Medronho Universidade do Federal do Rio de Janeiro, Faculdade de Medicina. Rio de Janeiro, Brasil
Valdiléa Gonçalves Veloso Fundação Instituto Oswaldo Cruz, Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, Brasil
Josiane Iole França Lopes Hemorio. Estado do Rio de Janeiro, Brasil
Luis Cristovão de Moraes Sobrino Porto Universidade do Estado do Rio de Janeiro, Laboratório de Histocompatibilidade e Criopreservação, Policlínica Piquet Carneiro. Rio de Janeiro, Brasil
Alexandre Chieppe Secretaria de Estado do Rio de Janeiro. Rio de Janeiro, Brasil
Guilherme Loureiro Werneck Universidade do Federal do Rio de Janeiro, Instituto de Estudos em Saúde Coletiva e Universidade do Estado do Rio de Janeiro, Instituto de Medicina Social. Rio de Janeiro, Brasil https://orcid.org/0000-0003-1169-1436

DOI:

https://doi.org/10.1590/SciELOPreprints.404

Keywords:

COVID-19, Blood donors, Prevalence, Serology, SARS-CoV-2

Abstract

Background: In Brazil, mathematical models for deriving estimates and projections of COVID-19 cases have been developed without data on asymptomatic SARS-CoV-2 infection. We estimated the seroprevalence of antibodies to SARS-CoV-2 among blood donors in the State of Rio de Janeiro.

Methods: Data were collected on 2,857 blood donors from April 14 to 27, 2020. We report the crude prevalence of antibodies to SARS-CoV-2, the weighted prevalence by the total state population, and adjusted prevalence estimates for test sensitivity and specificity. To establish the correlates of SARS-CoV-2 prevalence, we used logistic regression models. The analysis included period and site of blood collection, sociodemographic characteristics, and place of residence.

Results: The proportion of SARS-Cov-2 positive tests without any adjustment was 4.0% (95% CI 3.3-4.7%), and the weighted prevalence was 3.8% (95% CI 3.1-4.5%). Further adjustment by test sensitivity and specificity produced lower estimates, 3.6% (95% CI 2.7-4.4%) and 3.3% (95% CI 2.6-4.1%), respectively. The variable most significantly associated with the crude prevalence was the period of blood collection: the later the period, the higher the prevalence. Regarding socio-demographic characteristics, the younger the blood donors, the higher the prevalence, and the lower the educational level, the higher the odds of a positive SARS-Cov-2 antibody. Similar results were found for the weighted prevalence.

Discussion: Although our findings resulted from a convenience sample, they match some basic premises: the increasing trend over time, since the epidemic curve in the state is still on the rise; the higher prevalence among the youngest who are more likely to circulate; and the higher prevalence among the less educated as they have more difficulties in following the social distancing recommendations. Despite the study limitations, it is possible to infer that protective levels of natural herd immunity to SARS-CoV-2 are far from being reached in Rio de Janeiro.