Factors Associated With a Persistent Seronegative Status 1 Year After a SARS-CoV-2 Massive Infection Outbreak in Community Dwellers Living in Rural Ecuador: A Prospective Population-based Study

BACKGROUND: The SARS-CoV-2 pandemic is affecting millions of people living in rural areas of Low- and Middle-Income Countries and is causing an already anticipated devastating effect on the health and economics of these populations. More information is needed to modify behaviors that may counterbalance the consequences of mass spread of the virus in these underserved communities. This study aimed to identify factors associated with a persistent SARS-CoV-2 seronegative status 1 year after a massive infection outbreak in middle-aged and older adults living in rural Ecuador. METHODS: Individuals enrolled in the Atahualpa Project Cohort as of March 2020 received 5 rounds of tests for determination of SARS-CoV-2 antibodies in blood. Individuals who remained seronegative up to April 2021 were considered “persistently seronegative.” An adjusted Poisson regression model was fitted to estimate the incidence risk ratio of factors directly or inversely associated with a persistent seronegative status. RESULTS: A total of 673 individuals received baseline tests. Thirty-one declined consent or died and 429 seroconverted, leaving 213 seronegative subjects. Average SARS-CoV-2 incidence rate was 9.87 events (95% C.I.: 8.91-10.83) per 100 person-months of observation. The use of flushing toilet systems (instead of open latrines) increased 1.5 times the possibility of remaining seronegative. Likewise, every additional bedroom in the house increased by 15% the possibility of remaining seronegative. In contrast, every additional person in the house and having high cholesterol levels significantly reduced the possibility of remaining seronegative. CONCLUSIONS: The use of flushing toilet systems and the number of bedrooms in the house directly influenced the possibility of remaining seronegative among individuals living in this rural setting. Study results also demonstrated a sustained transmission of the virus even after a significant proportion of the population has been infected. Our findings reinforce the mass spread of SARS-CoV-2 in rural communities.