Estimate of the Basic Reproduction Number for COVID-19: A Systematic Review and Meta-analysis

OBJECTIVES: The outbreak of coronavirus disease 2019 (COVID-19) is one of the main public health challenges currently facing the world. Because of its high transmissibility, COVID-19 has already caused extensive morbidity and mortality in many countries throughout the world. An accurate estimation of the basic reproduction number (R(0)) of COVID-19 would be beneficial for prevention programs. In light of discrepancies in original research on this issue, this systematic review and meta-analysis aimed to estimate the pooled R(0) for COVID-19 in the current outbreak. METHODS: International databases (including Google Scholar, Science Direct, PubMed, and Scopus) were searched to identify studies conducted regarding the R(0) of COVID-19. Articles were searched using the following keywords: “COVID-19” and “basic reproduction number” or “R(0).” The heterogeneity among studies was assessed using the I(2) index, the Cochran Q test, and T(2). A random-effects model was used to estimate R(0) in this study. RESULTS: The mean reported R(0) in the identified articles was 3.38±1.40, with a range of 1.90 to 6.49. According to the results of the random-effects model, the pooled R(0) for COVID-19 was estimated as 3.32 (95% confidence interval, 2.81 to 3.82). According to the results of the meta-regression analysis, the type of model used to estimate R(0) did not have a significant effect on heterogeneity among studies (p=0.81). CONCLUSIONS: Considering the estimated R(0) for COVID-19, reducing the number of contacts within the population is a necessary step to control the epidemic. The estimated overall R(0) was higher than the World Health Organization estimate.