Serial interval and incubation period of COVID-19: a systematic review and meta-analysis

Author address

Author name: Muluneh Alene (MPH in Biostatistics)

Affiliation:  Debre Markos University

P.O.Box: 296

Phone: +251922894376

Email: mulunehadis@gmail.com

Abstract

Background: Understanding epidemiological parameters that determine the transmission dynamics of COVID-19 is essential for public health practices. Globally, a number of studies were conducted to estimate the average serial interval and incubation period of COVID-19.  Pooling findings of existing studies that estimate the average serial interval and incubation period of COVID-19 significantly strengthen the quality of evidence. Thus, this meta-analysis was aimed to determine the overall pooled average estimate of serial interval and incubation period of COVID-19 using existing literatures.

Methods: We followed the preferred reporting items for systematic review and meta-analysis (PRISMA) checklist to present this systematic review and meta-analysis. A comprehensive search strategy was carried out from international electronic databases (Google Scholar, PubMed, Science Direct, Web of Science, CINAHL, and Cochrane Library) by two experienced review (MAA and DBK) authors. We included articles that satisfied the eligibility criteria of the study. The risk of bias of the original studies was assessed using the Newcastle-Ottawa Scale (NOS) adapted for cross-sectional studies. After extracting all relevant data using Microsoft Excel, it was analyzed using R software. Primary estimates were pooled using a random-effects model for each outcome. The pooled estimates with 95% confidence interval was presented using forest plots. Funnel plots and Egger’s test were used to assess publication bias.

Results: We combined a total of 23 studies to estimate the overall mean serial interval of COVID-19. The mean serial interval of COVID-19 ranged from 4. 2 to 7.5 days. Our meta-analysis showed that the weighted pooled mean serial interval of COVID-19 was 5.2 (95%CI: 4.9-5.5) days. Additionally, to pool the mean incubation period of COVID-19, we included 14 articles. The mean incubation period of COVID-19 also ranged from 4.8 to 9 days. Accordingly, the weighted pooled mean incubation period of COVID-19 was 6.5 (95%CI: 5.9-7.1) days.

Conclusions: This systematic review and meta-analysis showed that the weighted pooled mean serial interval and incubation period of COVID-19 were 5.2, and 6.5 days, respectively. This study concluded that the mean serial interval of COVID-19 is shorter than the mean serial interval of SARS and MERS. However, the mean incubation period of COVID-19 is longer than the mean incubation period of SARS and MERS. This finding suggests that substantial numbers of COVID-19 cases will be attributed to presymptomatic transmission.

Keywords: COVID-19, Serial interval, Incubation period, Meta-analysis