Prevalence of IgG antibodies induced by the SARS‐COV‐2 virus in asymptomatic adults in Nuevo Leon, Mexico

Rodríguez‐Vidales, Edgar P.; Garza‐Carrillo, Denise; Pérez‐Trujillo, José J.; Robles‐Rodríguez, Olivia A.; Salinas‐Martínez, Ana María; Montes de Oca‐Luna, Roberto; Treviño‐Garza, Consuelo; De la O‐Cavazos, Manuel E.

Population‐based immunoglobulin G (IgG) seroprevalence studies in asymptomatic individuals in Latin America are scarce. The objective of the study was to estimate the prevalence and geographic distribution of IgG antibodies induced by natural SARS‐CoV‐2 infection in asymptomatic adults, 5–8 months after the first case was reported in a northeastern state of Mexico. This was a population‐based cross‐sectional study carried out in Nuevo Leon during August–November 2020. Individuals ≥18 years with no previous diagnosis or symptoms suggestive of COVID‐19 were consecutively screened in one of the busiest subway stations. Also, a search for eligible individuals was done from house‐to‐house, after selecting densely populated geographic sectors of each of the municipalities of the metropolitan area (n = 4495). The IgG antibodies to SARS‐CoV‐2 nucleocapsid protein were analyzed. The IgG antibody positivity rate was 27.1% (95% confidence interval [CI]: 25.8, 28.4); there were no differences by sex or age (p > 0.05). Analysis by month showed a gradual increase from 11.9% (August) to 31.9% (November); Week 39 had the highest positivity rate (42.2%, 95% CI: 34.2, 50.7). Most people did not have evidence of previous SARS‐CoV‐2 infection. Preventive measures and promotion of the COVID‐19 vaccine should be strengthened.