PLoS ONE (Jan 2021)

COVID-19 seroprevalence in military police force, Southern Brazil.

  • Alessandro C Pasqualotto,
  • Paula de Castro Pereira,
  • Daiane F Dalla Lana,
  • Alexandre V Schwarzbold,
  • Marco S Ribeiro,
  • Cezar V W Riche,
  • Cristiani Pilati P Castro,
  • Paula L Korsack,
  • Paulo Emilio B Ferreira,
  • Guilherme de C Domingues,
  • Giorgia T Ribeiro,
  • Marcelo Carneiro,
  • Cassia Ferreira B Caurio,
  • Izadora Clezar da S Vasconcellos,
  • Lidiana M Knebel,
  • Lucas Zamberlan,
  • Andressa P Stolz,
  • Macarthur Vilanova,
  • Guilherme Watte,
  • Antonio N Kalil

DOI
https://doi.org/10.1371/journal.pone.0249672
Journal volume & issue
Vol. 16, no. 4
p. e0249672

Abstract

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BackgroundLimited 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.MethodsSampling 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.ConclusionThe 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.