The latent period of coronavirus disease 2019 with SARS‐CoV‐2 B.1.617.2 Delta variant of concern in the postvaccination era

INTRODUCTION: Emerging variants of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) have resulted in new challenges for epidemic prevention and control worldwide. However, little is known about the latent period of coronavirus disease by the SARS‐CoV‐2 Delta variant of concern (VOC) in the postvaccination era. METHODS: The epidemiology and clinical data of cases with confirmed SARS‐CoV‐2 Delta VOC infection were retrospective collected. Dates of the first positive PCR test were collected to estimate the distribution of latent period. RESULTS: Of the 40 patients, 16 were male (40%). The median age of patients was 47.5 years. The median latent period of patients was 6.0 days (interquartile range [IQR], 4.0−9.0 days) and the longest latent period was 13.0 days after exposure. The latent periods were longer in male patients compared to female patients (median, 8.5 days vs. 5.0 days, p = .041). The median latent period was comparable among fully vaccinated cases (6.5 days), no vaccinated cases (7.5 days), and partially vaccinated cases (5.5 days). CONCLUSIONS: The median latent period of SARS‐CoV‐2 Delta VOC infection was 6.0 days. The latent period between vaccinated and non‐vaccinated patients was not significantly different. The 14‐day quarantine program is sufficient to prevent the transmission of COVID‐19 by Delta VOC in the postvaccination era.