Three-quarters attack rate of SARS-CoV-2 in the Brazilian Amazon during a largely unmitigated epidemic.
Buss LF., Prete CA., Abrahim CMM., Mendrone A., Salomon T., de Almeida-Neto C., França RFO., Belotti MC., Carvalho MPSS., Costa AG., Crispim MAE., Ferreira SC., Fraiji NA., Gurzenda S., Whittaker C., Kamaura LT., Takecian PL., da Silva Peixoto P., Oikawa MK., Nishiya AS., Rocha V., Salles NA., de Souza Santos AA., da Silva MA., Custer B., Parag KV., Barral-Netto M., Kraemer MUG., Pereira RHM., Pybus OG., Busch MP., Castro MC., Dye C., Nascimento VH., Faria NR., Sabino EC.
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.