Shorter Incubation Period among COVID-19 Cases with the BA.1 Omicron Variant

Hideo Tanaka, Tsuyoshi Ogata, Toshiyuki Shibata, Hitomi Nagai, Yuki Takahashi, Masaru Kinoshita, Keisuke Matsubayashi, Sanae Hattori and Chie Taniguchi
Additional contact information
Hideo Tanaka: Public Health Center of Neyagawa City, Neyagawa 572-0838, Japan
Tsuyoshi Ogata: Itako Public Health Center of Ibaraki Prefectural Government, Itako 311-2422, Japan
Toshiyuki Shibata: Public Health Center of Suita City, Suita 564-0072, Japan
Hitomi Nagai: Ibaraki Public Health Center of Osaka Prefectural Government, Ibaraki 567-8585, Japan
Yuki Takahashi: Fujiidera Public Health Center of Osaka Prefectural Government, Fujiidera 583-0024, Japan
Masaru Kinoshita: Fujiidera Public Health Center of Osaka Prefectural Government, Fujiidera 583-0024, Japan
Keisuke Matsubayashi: Public Health Center of Suita City, Suita 564-0072, Japan
Sanae Hattori: Ibaraki Prefetural Office, Mito 310-0852, Japan
Chie Taniguchi: College of Nursing, Aichi Medical University, Nagakute 480-1195, Japan

IJERPH, 2022, vol. 19, issue 10, 1-7

Abstract: We aimed to elucidate the range of the incubation period in patients infected with the SARS-CoV-2 Omicron variant in comparison with the Alpha variant. Contact tracing data from three Japanese public health centers (total residents, 1.06 million) collected following the guidelines of the Infectious Diseases Control Law were reviewed for 1589 PCR-confirmed COVID-19 cases diagnosed in January 2022. We identified 77 eligible symptomatic patients for whom the date and setting of transmission were known, in the absence of any other probable routes of transmission. The observed incubation period was 3.03 ± 1.35 days (mean ± SDM). In the log-normal distribution, 5th, 50th and 95th percentile values were 1.3 days (95% CI: 1.0–1.6), 2.8 days (2.5–3.1) and 5.8 days (4.8–7.5), significantly shorter than among the 51 patients with the Alpha variant diagnosed in April and May in 2021 (4.94 days ± 2.19, 2.1 days (1.5–2.7), 4.5 days (4.0–5.1) and 9.6 days (7.4–13.0), p < 0.001). As this incubation period, mainly of sublineage BA.1, is even shorter than that in the Delta variant, it is thought to partially explain the variant replacement occurring in late 2021 to early 2022 in many countries.

Keywords: SARS-CoV-2; COVID-19; Omicron variant; incubation period; Alpha variant; Japanese Public Health Center; contact tracing (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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