Three-quarters attack rate of SARS-CoV-2 in the Brazilian Amazon during a largely unmitigated epidemic
Lewis Buss, Carlos A. Prete, Claudia M. M. Abrahim, Alfredo Mendrone, Tassila Salomon, Cesar de Almeida‐Neto, Rafael Freitas de Oliveira França, Maria Carolina T. D. Belotti, Maria P. S. S. Carvalho, Allyson Guimarães Costa, Myuki Alfaia Esashika Crispim, Suzete C. Ferreira, Nelson Abrahim Fraiji, Susie Gurzenda, Charles Whittaker, Leonardo Tadashi Kamaura, Pedro Losco Takecian, Pedro S. Peixoto, Márcio K. Oikawa, Anna S. Nishiya, Vanderson Rocha, Nanci A. Salles, Andreza Aruska de Souza Santos, Martirene A. da Silva, Brian Custer, Kris V. Parag, Manoel Barral‐Netto, Moritz U. G. Kraemer, Rafael H. M. Pereira, Oliver G. Pybus, Michael P. Busch, Márcia C. Castro, Christopher Dye, Vítor H. Nascimento, Nuno R. Faria, Éster Cerdeira Sabino
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread rapidly in Manaus, the capital of Amazonas state in northern Brazil. The attack rate there is an estimate of the final size of the largely unmitigated epidemic that occurred in Manaus. We use a convenience sample of blood donors to show that by June 2020, 1 month after the epidemic peak in Manaus, 44% of the population had detectable immunoglobulin G (IgG) antibodies. Correcting for cases without a detectable antibody response and for antibody waning, we estimate a 66% attack rate in June, rising to 76% in October. This is higher than in São Paulo, in southeastern Brazil, where the estimated attack rate in October was 29%. These results confirm that when poorly controlled, COVID-19 can infect a large proportion of the population, causing high mortality.