RESUMO
OBJECTIVES: We aimed to estimate the time-varying transmission dynamics of COVID-19 in China, Wuhan City, and Guangdong province, and compare to that of severe acute respiratory syndrome (SARS). METHODS: Data on COVID-19 cases in China up to 20 March 2020 was collected from epidemiological investigations or official websites. Data on SARS cases in Guangdong Province, Beijing, and Hong Kong during 2002-3 was also obtained. We estimated the doubling time, basic reproduction number (R0), and time-varying reproduction number (Rt) of COVID-19 and SARS. RESULTS: As of 20 March 2020, 80,739 locally acquired COVID-19 cases were identified in mainland China, with most cases reported between 20 January and 29 February 2020. The R0 value of COVID-19 in China and Wuhan was 5.0 and 4.8, respectively, which was greater than the R0 value of SARS in Guangdong (R0 = 2.3), Hong Kong (R0 = 2.3), and Beijing (R0 = 2.6). At the start of the COVID-19 epidemic, the Rt value in China peaked at 8.4 and then declined quickly to below 1.0 in one month. With SARS, the Rt curve saw fluctuations with more than one peak, the highest peak was lower than that for COVID-19. CONCLUSIONS: COVID-19 has much higher transmissibility than SARS, however, a series of prevention and control interventions to suppress the outbreak were effective. Sustained efforts are needed to prevent the rebound of the epidemic in the context of the global pandemic.