We followed the COVID-19 pandemic in Manaus, one of the epicenters of COVID-19 in Brazil, using an epidemiological mathematical model and made five main conclusions. First, in early 2022, the actual cases exceed officially reported data by up to 8 times. Second, despite vaccination campaigns, the collective immunity threshold necessary was insufficient to contain severe cases of COVID-19. Next, the low observed mortality demonstrated the effectiveness of vaccination. Next, the drop in the vaccination rate combined with immune escape by the Omicron sub-variants (BA.2.12.1, BA.4, and BA.5) resulted in new wave after November 2022. Finally, to minimize severe cases of COVID-19, we need to raise vaccination thresholds above 90-95% of the entire population including children aged 6 months and older and require booster doses at least in four-month intervals. This approach would help to prevent severe cases of COVID-19 that cause hospitalizations and deaths.
Keywords: Amazonas; Brazil; COVID-19; Delta variant; Epidemiological risk; Manaus; Omicron variants; Pandemic; Vaccination.
© 2024. The Author(s), under exclusive licence to Springer Nature Limited.