Understanding the transmission dynamics and the severity of the novel coronavirus disease 2019 (COVID-19) informs public health interventions, surveillance, and planning. Two important parameters, the basic reproduction number (R0) and case fatality rate (CFR) of COVID-19, help in this understanding process. The objective of this study was to estimate the R0 and CFR of COVID-19 and assess whether the parameters vary in different regions of the world. We carried out a systematic review to retrieve the published estimates of the R0 and the CFR in articles from international databases between 1st January and 31st August 2020. Random-effect models and Forest plots were implemented to evaluate the mean effect size of the R0 and the CFR. Furthermore, the R0 and CFR of the studies were quantified based on geographic location, the tests/thousand population, and the median population age of the countries where studies were conducted. The I2 statistic and the Cochran's Q test were applied to assess statistical heterogeneity among the selected studies. Forty-five studies involving R0 and thirty-four studies involving CFR were included. The pooled estimation of the R0 was 2.69 (95% CI: 2.40, 2.98), and that of the CFR was 2.67 (2.25, 3.13). The CFR in different regions of the world varied significantly, from 2.51 (2.12, 2.95) in Asia to 7.11 (6.38, 7.91) in Africa. We observed higher mean CFR values for the countries with lower tests (3.15 vs. 2.16) and greater median population age (3.13 vs. 2.27). However, the R0 did not vary significantly in different regions of the world. An R0 of 2.69 and CFR of 2.67 indicate the severity of the COVID-19. Although R0 and CFR may vary over time, space, and demographics, we recommend considering these figures in control and prevention measures.
Estimation of novel coronavirus (covid-19) reproduction number and case fatality rate: a systematic review and meta-analysis