Anti-SARS-CoV-2 antibodies among indigenous populations of the Brazilian Amazon: a cross-sectional study

Abstract

ObjectivesThe emergence of SARS-CoV-2 and its pandemic spread generated serious concern about the impact of the infection on vulnerable indigenous populations of the Brazilian Amazon. Thus, this study aimed to perform a seroepidemiological survey of anti-SARS-CoV-2 antibodies in those populations.SettingSix indigenous ethnic groups living in the State of Pará (Northern Brazil) were investigated. The villages of Xikrin do Bacajá, Assurini, Araweté, Parakanã, Munduruku and Kararaô were visited from October 2020 to January 2021.Design and participantsWe performed a cross-sectional study to investigate the prevalence of anti-spike (S1) IgG antibodies. Plasma was tested for the presence of anti-SARS-CoV-2 IgM and IgG antibodies using two assays (a lateral flow rapid test and an ELISA). A total of 1185 individuals of both sexes were enrolled in the study.ResultsThe prevalences of IgM and IgG antibodies were 6.9% and 68.1%, respectively, ranging from 0% to 79.6%, with significant differences (p<0.001) between age groups in three communities (Araweté, Xikrin and Munduruku) and a virulence rate of 0.86%. The overall IgG prevalence obtained by rapid tests and ELISAs were similar, and the agreement of the results between the two tests was 80%, which was classified as good (kappa=0.4987; p<0.001; sensitivity of 82.1% and specificity of 71.6%). Herd immunity was probably attained, similar to that found in other communities of the Amazon.ConclusionsSARS-CoV-2 spread rapidly among the indigenous populations investigated, but it had a low mortality rate. It is necessary to expand serological investigations to other communities in the Amazon region of Brazil.

Seroepidemiology of SARS-CoV-2 on a partially vaccinated island in Brazil: Determinants of infection and vaccine response

“…Compared to surveys conducted in Brazil around mid-2021 the seroprevalence of antibodies against SARS-CoV-2 in our sample (53.61%) was higher than other studies reported in the South and Southeast regions of Brazil ( 14 , 16 , 17 ), being closer to rates observed at that time in the North region ( 18 , 19 ) and in indigenous populations ( 20 , 21 ). With a vaccine coverage of 37% in our study population, the large difference in seroprevalence between vaccinated (90.5%) and unvaccinated (31%) residents confirmed findings from other studies ( 22 ) of how vaccination decisively contributes to the population's immunity, even in an area with a high prevalence of infection-induced antibodies after exposure to a pandemic for more than a year.…”

COVID-19 vaccination, incidence, and mortality rates among indigenous populations compared to the general population in Brazil: Describing trends over time

“…Difficulties in access to healthcare, along with characteristics of social organization and genetic susceptibilities intrinsic to indigenous peoples, may have contributed to these outcomes. 4 , 38…”

“…The introduction of new infectious agents among indigenous groups is alarming due to the potentially lower variability of immune response and other genetic susceptibilities, leading to increased disease severity and mortality. 4 In addition, cultural aspects such as the social organization in indigenous villages may challenge physical distancing measures and facilitate the spread of SARS-CoV-2. 3 Economic activities in indigenous lands, such as commercial agriculture, mining, and road constructions, increased under Bolsonaro's government in Brazil, exponentiating the likelihood of exposure of indigenous populations to the virus.…”

“…Furthermore, data from Kaiapó indigenous population shows that SARS-CoV2 infection spread rapidly in the population, highlighting the importance of indigenous health policies to minimize the impact of pandemic on these communities. 3 , 4 …”

The dynamics and determinants of specific systemic and mucosal antibody responses to SARS-CoV-2 in three adult cohorts in the Ecuadorian Andes: a study protocol

“…[1][2][3] Numerous seroprevalence studies have been conducted in the Latin American region, both population-based studies and studies focusing on specific populations (healthcare (HCW) or first-line workers, prison workers, indigenous populations, elderly populations, etc). [4][5][6][7][8][9][10][11][12][13][14][15] The reported seroprevalence is highly heterogenous between studies (10,4% -68,1 %), varying by study population, characteristics of the COVID-19 epidemic at the time of sampling, and differences in sociodemographic factors. [4][5][6][7][8][9][10][11][12][13][14][15] Factors associated with increasing risk of seropositivity include ethnicity (indigenous or Afro-descent), presence of COVID-19 symptoms, past history of COVID-19 or close contacts, lower educational level, and working night shifts (for HCW) or in a prison.…”