JMIR Publications

ABSTRACT

Background:

Data on how SARS-CoV-2 enters and spreads in a population are essential for guiding public policies.

Objective:

This study sought to understand the transmission dynamics of SARS-CoV-2 in Brazilian small towns during the early phase of the epidemic, to identify core groups that can serve as initial source of infection as well as factors associated with higher risk of Covid-19.

Methods:

Two population-based seroprevalence studies, one household survey and a case-control study were conducted in two small towns in the southeastern Brazil. In the population-based studies, 400 people were evaluated in each town, there were 40 homes in the household survey, and 95 cases and 450 controls in the case-control study. SARS-CoV-2 serology testing was performed on participants and a questionnaire was applied. Prevalence, household secondary infection rate and factors associated with infection were assessed.

Results:

Higher seroprevalence of SARS-CoV-2 was observed in the town with greater proportion of logistics workers. The secondary household infection rate was 49.1% and it was observed that in most households (70%) the index case was a logistics worker. The case-control study revealed that being a logistics worker (OR=13.1) or living with one (OR=4.6) increases the risk of infection. In addition, having contact with a confirmed case and living with more than four people were also risk factors.

Conclusions:

Our study shows a strong association between logistics workers and the risk of SARS-CoV-2 infection as well as highlights the key role of these workers for viral spread in small towns. These findings indicate the need to focus on this population to determine Covid-19 prevention and control strategies.