COVID-19 seroprevalence in military police force, Southern Brazil

• Published in: PloS one 2021-04, Vol.16 (4), p.e0249672-e0249672
• Main Authors: Pasqualotto, Alessandro C, Pereira, Paula de Castro, Lana, Daiane F Dalla, Schwarzbold, Alexandre V, Ribeiro, Marco S, Riche, Cezar V W, Castro, Cristiani Pilati P, Korsack, Paula L, Ferreira, Paulo Emilio B, Domingues, Guilherme de C, Ribeiro, Giorgia T, Carneiro, Marcelo, Caurio, Cassia Ferreira B, Vasconcellos, Izadora Clezar da S, Knebel, Lidiana M, Zamberlan, Lucas, Stolz, Andressa P, Vilanova, Macarthur, Watte, Guilherme, Kalil, Antonio N
• Format: Article
• Language: English
• Subjects: Adult; Antibodies; Asymptomatic; Biology and life sciences; Brazil; Brazil - epidemiology; Computer programs; Coronaviruses; COVID-19; COVID-19 - diagnosis; COVID-19 - epidemiology; COVID-19 Serological Testing; Cross-Sectional Studies; Demographic aspects; Distribution; Earth Sciences; Editing; Enzyme-linked immunosorbent assay; Epidemics; Ethylenediaminetetraacetic acids; Female; Gels; Genetic aspects; Health aspects; Humans; IgG antibody; Immunoglobulin A; Immunoglobulin G; Male; Medical supplies; Medicine and Health Sciences; Middle Aged; Military; Military Personnel; Military police; Pandemics; People and places; Police; Research and Analysis Methods; Reviews; SARS-CoV-2 - isolation & purification; Separators; Seroepidemiologic Studies; Serology; Severe acute respiratory syndrome coronavirus 2; Social Sciences; Software; Standard deviation; Tubes; Viral diseases
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0249672

Limited data is available regarding the frequency of COVID-19 in populations that are highly exposed to SARS-CoV-2. In this cross-section study we evaluated COVID-19 seroprevalence in military police forces of 10 major cities in Rio Grande do Sul, South of Brazil. Sampling was randomly performed in clusters, in respect to the number of professionals at service per city and military unit. Research subjects were evaluated on July 23, 2020 (first wave peak in Brazil). Clinical information was obtained, and venous blood was taken for ELISA testing (IgA, and IgG antibodies). Sample size consisted of 1,592 military workers (33.6% of study population). They were mostly man (81.2%) and young (median 34 years-old). Most had been asymptomatic (75.3%) during pandemic, and 27.5% reported close contact with COVID-19 cases (after a median time of 21 days). Antibodies were detected in 3.3% of the participants, mostly IgA (2.7%), and IgG (1.7%). After 3 weeks, 66.7% of IgA and IgG results turned negative, in addition to 78.3% and 100% of borderline IgA and IgG results, respectively. The seroprevalence of COVID-19 amongst military police was at least 3.4 higher than the findings of other studies performed in the general population, in the same cities and dates. Most detectable antibodies were of IgA class, which implies recent exposure. Asymptomatic people were more prone to have negative antibody titters in the second run.