Prevalence of SARS-CoV-2 IgG antibodies in a population from Veracruz (Southeastern Mexico)

Introduction/Aim Recent studies have shown that seroprevalence is quite variable depending on the country, the population and the time of the pandemic in which the serological tests are performed. Here, we investigated the prevalence of IgG antibodies against SARS-CoV-2 in a population living in Veracruz City, México. Methods From of June 1 to July 31, 2020, the consecutive adult patients (age ≥18 years) that attended 2 ambulatory diagnostic private practice centers for testing were included. Samples were run on the Abbott Architect instrument using the commercial Abbott SARS-CoV-2 IgG assay. The main outcome was seroprevalence. Demographics, previous infection to SARS-CoV-2 (according to a previous positive polymerase-chain reaction nasopharyngeal swab), self-suspicious of virus of infection (according to have in the previous 4 weeks either fever, headache, respiratory symptoms but not a confirmatory PCR) or no having symptoms were also evaluated. Results A total of 2174 subjects were tested, included 53.6% women (mean age 41.8±15.17 years, range 18-98 years). One thousand and forty-one (52.5%) subjects were asymptomatic, 722 (33.2%) had suspicious of infection and 311 (14.3%) had previous infection. Overall, 642 of 2174 (29.5% [95% CI 27.59%-31.47%]) of our population were seropositive. Seropositivity among groups was 21.3% in asymptomatic, 23.4% in self-suspicious patients and 73.9% in previous infection patients. Conclusions We found one of the highest seroprevalences reported for SARS-CoV-2 worldwide in asymptomatic subjects (21.3%) as well in subjects with self-suspicious of COVID-19 (23.4%). The number of infected subjects in our population is not encouraging and it should be interpreted with caution.