IgG seroprevalence against SARS-CoV-2 in a cohort of 449 non-hospitalized, high-risk exposure individuals

COVID-19 pandemic caused by SARS-CoV-2 led the Spanish government to impose a national lockdown in an attempt to control the spread of the infection. Mobility restrictions but also the requirement of a medical prescription to gain access to serological testing for COVID-19 were included among the measures. Under this scenario, between April 15th to June 15th, 2020, we performed a seroprevalence observational study including 449 individuals that fulfill prescription requirements: manifesting COVID-19 compatible symptoms, being in contact with a COVID-19 confirmed case or belonging to essential occupations including healthcare workers, firefighters or public safety personnel such as police. Importantly, none of the participants was hospitalized. Altogether, we studied this specific, non-commonly addressed cohort for SARS-CoV-2 seroprevalence, uncovering intrinsic features of great demographic interest. The overall rate of IgG seropositivity was 33.69% (95% CI: 29.27 – 38.21). This seroprevalence was comparable between different occupations performed by the participants. However, contacts with confirmed cases associated positively with IgG+ results, with stronger correlation if being a household member. The number of symptoms also correlated positively with IgG+ prevalence. Ageusia/anosmia, pneumonia and cutaneous manifestations were the top-three symptoms that most strongly associated with IgG+ seroprevalence. However, while pneumonia and cutaneous manifestations were barely present in our cohort, fever, ageusia/anosmia and asthenia were the most frequently symptoms described within IgG+ subjects. Therefore, our data illustrate how specific cohorts display heterogeneous characteristics that should be taken into account when identifying population seroprevalence against SARS-CoV-2 and key defining symptoms for COVID-19.