Risk Management and Healthcare Policy (Aug 2020)
Probable Longer Incubation Period for Elderly COVID-19 Cases: Analysis of 180 Contact Tracing Data in Hubei Province, China
Abstract
Jingyi Dai,1 Lin Yang,2 Jun Zhao2 1Department of Infectious Diseases, The Third People’s Hospital of Kunming City, Kunming, Yunnan Province, People’s Republic of China; 2School of Public Health and Management, Hubei University of Medicine, Shiyan, Hubei Province, People’s Republic of ChinaCorrespondence: Jun ZhaoSchool of Public Health and Management, Hubei University of Medicine, 30 South Renmin Road, Shiyan, Hubei 442000, People’s Republic of ChinaEmail [email protected]: Factors associated with the incubation period of COVID-19 are not fully known. The aim of this study was to estimate the incubation period of COVID-19 using epidemiological contact tracing data, and to explore whether there were different incubation periods among different age gr1oups.Methods: We collected contact tracing data in a municipality in Hubei province during the full outbreak period of COVID-19. The exposure periods were inferred from the history of travel in Wuhan and/or history of exposure to confirmed cases. The incubation periods were estimated using parametric accelerated failure time models accounting for interval censoring of exposures.Results: The incubation period of COVID-19 follows a Weibull distribution and has a median of 5.8 days with a bootstrap 95% CI: 5.4– 6.7 days. Of the symptomatic cases, 95% showed symptoms by 14.3 days (95% CI: 13.0– 15.7), and 99% showed symptoms by 18.7 days (95% CI: 16.7– 20.9). The incubation periods were not found significantly different between male and female. Elderly cases had significant longer incubation periods than young age cases (HR 1.49 with 95% CI: 1.09– 2.05). The median incubation period was estimated at 4.0 days (95% CI: 3.5– 4.4) for cases aged under 30, 5.8 days (95% CI: 5.6– 6.0) for cases aged between 30 and 59, and 7.7 days (95% CI: 6.9– 8.4) for cases aged greater than or equal to 60.Conclusion: The current practice of a 14-day quarantine period in many regions is reasonable for any age. Older people infected with SARS-CoV2 have longer incubation period than that of younger people. Thus, more attention should be paid to asymptomatic elderly people who had a history of exposure.Keywords: infectious disease, coronavirus, incubation period, epidemiology
