The Impact of SARS-CoV-2 Variant to COVID-19 Epidemic in Brazil
AbstractThe impact of SARS-CoV-2 dominant global lineages to COVID-19 epidemics is for the first time modeled by an adaptation of the deterministic SEIR Model. Such a strategy may be applied worldwide to predict forecasts of the outbreak in any infected country. The objective of this study is to forecast the outcome of the epidemic in Brazil as a first cohort study case. The basic modeling design takes under consideration two of SARS-CoV-2 dominant strains, and a time-varying reproduction number to forecast the disease transmission behavior. The study is set as a country population-based analysis. Brazilian official published data from February 25 to August 30 2020 was employed to adjust a couple of epidemiological parameters in this cohort study. The population-based sample in this study, 4.2 Million Brazilians during the study period, is the number of confirmed cases on exposed individuals. Model parameters were estimated by minimizing the mean squared quadratic errors. The main outcomes of the study follows: The percentage values of non-symptomatic and symptomatic COVID-19 hosts were estimated to be respectively (54 ± 9) % and (46 ± 9) %. By the end of 2020, the number of confirmed cases in Brazil, within 95% CI, is predicted to reach 6 Million (5-7), and fatalities would account for 180.103 (160–200).103. Estimated forecast obtained preserving or releasing the NPIs during the last quarter of 2020, are included. Data points for extra three weeks were added after the model was complete, granting confidence on the outcomes. In 2020 the total number of exposures individuals is estimated to reach 13 ± 1 Million, 6.2% of the Brazilian population. Regarding the original SARS-CoV-2 form and its variant, the only model assumption is their distinct incubation rates. The variant SARS-CoV-2 form, as predicted by the SEIR adopted model, reaches a maximum of 96% of exposed individuals as previously reported for South America. By the end of 2020, a fraction in the range of 15–35 percentages of susceptible Brazilian individuals is to be depleted. Sufficient depletion of susceptibility (by NPIs or not) has to be achieved to weaken the global dynamics spread.