Growth rate and acceleration analysis of the COVID-19 pandemic reveals the effect of public health measures in real time

We used moving regression to model the growth rate (cases/day) and acceleration (cases/day2) of COVID-19 cases in 123 countries as of March 25th 2020. In countries entering stationary growth (China and South Korea) decline in acceleration was observable up to 1 week after severe restriction to human mobility was adopted as a preventive measure. Deceleration was detectable within 2 weeks, whereas stationary growth was reached within 6 weeks. These results corroborate that mass social isolation is a highly effective measure against the dissemination of SARS-CoV-2. We also found that the impact of public health measures could be evaluated in seemingly real-time by monitoring COVID-19 growth curves. Moreover, reasonable daily predictions of new cases were obtained (R2 ~ 0.95). Apart from the analysis of prevalence partitioned by country, moving regression can be easily applied to city, state, region or arbitrary territory data to help monitoring the local behavior of COVID-19 cases.