High anti-SARS-CoV-2 antibody seroconversion rates before the second wave in Manaus, Brazil, and the protective effect of social behavior measures: Results from the DETECTCoV-19 cohort.

Abstract

We report anti-SARS-CoV-2 nucleocapsid IgG seroconversion rates from a population-based cohort in Manaus, between August and November 2020, before the COVID-19 second wave in Brazil. Among seronegative and uninfected participants, we observed an overall incidence of 13.06% (95%CI, 11.52-14.79) and 6.78% (95%CI, 5.61-8.10) for symptomatic seroconversion. Risk factors for seroconversion were: having a COVID-19 case in the household, not wearing a mask during contact, relaxation of protective measures, and non-remote work. We observed an intense infection transmission period that preceded the second wave of COVID-19 in Manaus, and identified several modifiable behaviors that increased the risk of seroconversion.

SARS-CoV-2 antibody dynamics in blood donors and COVID-19 epidemiology in eight Brazilian state capitals

“…By contrast, among older women, who reached less than half the attack rate seen in men by June, the seroprevalence continued to increase. This heterogeneity in transmission in a location with high overall antibody prevalence meant that some groups remained relatively susceptible and perpetuated transmission at a lower level 24,25 . Other works suggest that socioeconomic condition also contributed to heterogeneity of SARS-CoV-2 spread in Manaus 25 , which is con rmed by the high seroprevalence observed in Black and less-educated donors (Supplementary Fig.…”

Intense SARS-CoV-2 transmission among affluent Manaus residents preceded the second wave of the epidemic in Brazil

“…In The Lancet Global Health , Pritesh Lalwani and colleagues 5 publish results from the DETECTCoV-19 cohort of adult Manaus residents tested for anti-SARS-CoV-2 nucleocapsid IgG antibodies using an in-house serology assay. Participants who provided a blood sample at the first study visit, between Aug 19 and Oct 2, 2020, were recalled for a second blood draw between Oct 19 and Nov 27, 2020.…”

“…9 Indeed, backing up this observation is the fact that 142 (20%) of the 712 positive cases at visit 1 had become negative by visit 2. 5 As most cases in the first wave in Manaus occurred in March and April, 2020, 4 months had elapsed before visit 1 in August. This allowed for significant positive–negative transition to have occurred before this blood draw.…”