First wave of SARS-CoV-2 in Santiago Chile: Seroprevalence, asymptomatic infection and infection fatality rate

The main objective of this study was to estimate the attack rate during the first wave of SARS-CoV-2 that reached a peak by the end of June 2020 in Santiago Chile. In a population based study antibodies against SARS-CoV-2 were measured to assess infection prevalence, as well as estimate asymptomatic cases, and infection fatality ratio. Immunochromatographic assays were used to detect IgM and IgG antibody isotypes.Seroprevalence reached 6.79 % (95 %CI 5.58 %−8.26 %) in the first 107 days of the pandemic, without significant differences among sex and age groups; this figure indicates an attack rate 2.8 times higher than the one calculated with registered cases. It also changes the fatality rate estimates, from 2.33 % case fatality rate to an estimated crude 1.00 % (CI95 % 0.97–1.03) infection fatality rate (adjusted for test performance 1.66 % [CI95 % 1.61–1.71]). Most seropositive were symptomatic (81,1 %).Our results provide better information to design early strategies that counterattack new health challenges in urban contexts.ga1