Modelling fatality curves of COVID-19 and the effectiveness of intervention strategies

Giovani L. Vasconcelos; Antônio M. S. Macêdo; Raydonal Ospina; Francisco A. G. Almeida; Gerson C. Duarte-Filho; Inês C. L. Souza

To summarize, this paper provides important insights into the time evolution of the accumulated number of deaths attributed to COVID-19, specially for countries, such as Italy, which are in the middle of the outbreak. Our modelling of the fatality curves is particularly relevant for the COVID-19 outbreak, because the actual number of infections remains largely unknown, so one is required to turn to proxy measures, such as mortality data, to gain a better understanding of the epidemics. The paper also shows how simple and soluble mathematical models can provide a rich theoretical framework in which to investigate some basic and deep aspects of epidemics dynamics. In particular, we have successfully applied the Richards growth model to describe the fatalities curves for four different countries, at different stages of the COVID-19 outbreak, namely China, Italy, Spain, Iran, and Germany. We also analysed the case of Brazil, which is in a much earlier stage of the outbreak, so here we resorted to a modified exponential growth model, also known as the generalized growth model. This model gave a good fit of the rising fatality curve of Brazil, from which we could estimate that as of this writing the time for doubling the number of fatalities from COVID-19 in Brazil is about 4 days.