Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Apr;29(4):814-817.
doi: 10.3201/eid2904.220854. Epub 2023 Mar 6.

Serial Intervals and Incubation Periods of SARS-CoV-2 Omicron and Delta Variants, Singapore

Kangwei Zeng, Santhya Santhya, Aijia Soong, Nitika Malhotra, Dhanushanth Pushparajah, Koh Cheng Thoon, Benny Yeo, Zheng Jie Marc Ho, Mark Chen I Cheng

Serial Intervals and Incubation Periods of SARS-CoV-2 Omicron and Delta Variants, Singapore

Kangwei Zeng et al. Emerg Infect Dis. 2023 Apr.

Abstract

We compared serial intervals and incubation periods for SARS-CoV-2 Omicron BA.1 and BA.2 subvariants and Delta variants in Singapore. Median incubation period was 3 days for BA.1 versus 4 days for Delta. Serial interval was 2 days for BA.1 and 3 days for BA.2 but 4 days for Delta.

Keywords: COVID-19; Delta; Omicron; SARS-CoV-2; Singapore; coronavirus disease; incubation period; respiratory infections; serial interval; severe acute respiratory syndrome coronavirus 2; variant of concern; viruses; zoonoses.

PubMed Disclaimer

Figures

Figure
Figure
Comparative analysis of serial interval of SARS-CoV-2 Delta and Omicron variants, Singapore. A) Incubation period using only transmission pairs with clear epidemiological links and single-day source exposure to primary case. B) Serial interval of all symptomatic transmission pairs. C) Serial interval of all symptomatic transmission pairs with transmissions within households. D) Serial interval of all symptomatic transmission pairs with transmissions outside of households (workplace, social events). Means and 95% CIs are based on fitting a Gamma distribution using the maximum-likelihood method. p values were calculated using Wilcoxon rank-sum test.
See this image and copyright information in PMC

References

    1. World Health Organization. Classification of Omicron (B.1.1.529): SARS-CoV-2 variant of concern [cited 2022 May 27]. https://www.who.int/news/item/26-11-2021-classification-of-omicron-(b.1....
    1. Pung R, Chiew CJ, Young BE, Chin S, Chen MI, Clapham HE, et al.; Singapore 2019 Novel Coronavirus Outbreak Research Team. Investigation of three clusters of COVID-19 in Singapore: implications for surveillance and response measures. Lancet. 2020;395:1039–46. 10.1016/S0140-6736(20)30528-6 - DOI - PMC - PubMed
    1. Kim D, Ali ST, Kim S, Jo J, Lim JS, Lee S, et al. Estimation of serial interval and reproduction number to quantify the transmissibility of SARS-CoV-2 Omicron variant in South Korea. Viruses. 2022;14:533. 10.3390/v14030533 - DOI - PMC - PubMed
    1. Brandal LT, MacDonald E, Veneti L, Ravlo T, Lange H, Naseer U, et al. Outbreak caused by the SARS-CoV-2 Omicron variant in Norway, November to December 2021. Euro Surveill. 2021;26:2101147. 10.2807/1560-7917.ES.2021.26.50.2101147 - DOI - PMC - PubMed
    1. Mefsin YM, Chen D, Bond HS, Lin Y, Cheung JK, Wong JY, et al. Epidemiology of Infections with SARS-CoV-2 Omicron BA.2 Variant, Hong Kong, January-March 2022. Emerg Infect Dis. 2022;28:1856–8. 10.3201/eid2809.220613 - DOI - PMC - PubMed

Supplementary concepts