Quarantine, relaxation and mutation explaining the CoViD-19 epidemic in Sao Paulo State (Brazil)

Yang, H. M.; Lombardi Junior, L. P. P.; Castro, F. F. M.; Yang, A. C.

Background: The continuous SARS-CoV-2 transmission in several countries could contribute to the mutations' appearance. The circulation of more virulent variants may increase the number of severe CoViD-19 needing hospital care and fatalities hugely. Methods: The partial quarantine in Sao Paulo State and further relaxation associated with the mutations are explained by a mathematical model based on the CoViD-19 natural history encompassing the age-dependent fatality. The model parameters were fitted considering the observed data from Sao Paulo State. Results: The partial quarantine was explained by the less virulent SARS-CoV-2 transmission, but the relaxation alone could not explain the epidemic observed in Sao Paulo State. However, more virulent variants plus the transmission among isolated individuals explained the increased CoViD-19 fatalities. Conclusions: The model described the CoViD-19 epidemic in Sao Paulo State by considering the partial quarantine, relaxation and mutations. The model provided a potential epidemiological scenario in the absence of mass vaccination.