Meta-analysis on Serial Intervals and Reproductive Rates for SARS-CoV-2

Objective: The aim of this study was to systematically review and meta-analyze all literature reporting the basic reproductive number (R 0 ), effective reproductive number (R e or R t ), and the serial interval (SI) values of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection. Summary Background Data: To assess the rate at which an infectious disease can spread in a population, the 2 measures, R 0 and R e or R t , are widely used. One of the parameters which influence the calculations is the SI, the period between symptom onset in an infector and an infectee. Methods: Web of Science, PubMed, Scopus, and Science Direct searching up to May 10, 2020, was performed. A continuous random-effect model was applied using the DerSimonian-Laird (inverse variance) method. Heterogeneity and publication bias were assessed. Results: A total of 39 articles met the eligibility criteria. Our results demonstrated the mean SI was 5.45 days, with the 95% confidence interval (CI) of 4.23 to 6.66. Pooled estimates for reproduction rates was 3.14 (95% CI: 2.69–3.59) for R 0 and 3.18 (95% CI: 2.89–3.47) for R t . Subgroup analysis by geographical region and date of publication revealed variations over both time and geography in calculated R 0 and R t values. As time has progressed, predicted R 0 and R t values had decreased globally. Conclusions: The study findings indicate that one SARS-CoV-2-infected person is likely to infect 3 persons, supporting that COVID-19 is a highly contagious disease. As an essential objective metrics implied in risk assessment for this emerging pandemic, monitoring R 0 and R e is necessary to indicate the effectiveness or failures of mitigation efforts.