Effectiveness of the severe acute respiratory syndrome coronavirus 2 Omicron BA.5 bivalent vaccine on symptoms in healthcare workers with BA.5 infection

Yosuke Hirotsu; Mika Takatori; Hitoshi Mochizuki; Masao Omata

doi:10.1016/j.jvacx.2024.100433

Effectiveness of the severe acute respiratory syndrome coronavirus 2 Omicron BA.5 bivalent vaccine on symptoms in healthcare workers with BA.5 infection

Vaccine X. 2024 Jan 6:17:100433. doi: 10.1016/j.jvacx.2024.100433. eCollection 2024 Mar.

Authors

Yosuke Hirotsu¹, Mika Takatori², Hitoshi Mochizuki^{1

3

4}, Masao Omata^{4

5}

Affiliations

¹ Genome Analysis Center, Yamanashi Central Hospital, 1-1-1 Fujimi, Kofu, Yamanashi, Japan.
² Division of Infection Control and Prevention, Yamanashi Central Hospital, 1-1-1 Fujimi, Kofu, Yamanashi, Japan.
³ Central Clinical Laboratory, Yamanashi Central Hospital, 1-1-1 Fujimi, Kofu, Yamanashi, Japan.
⁴ Department of Gastroenterology, Yamanashi Central Hospital, 1-1-1 Fujimi, Kofu, Yamanashi, Japan.
⁵ The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.

Abstract

Background: The infection status of healthcare workers (HCWs) with coronavirus disease 2019 has become a major concern worldwide. In this study, we investigated the efficacy of the number of vaccine doses on symptoms after BA.5-adapted bivalent vaccination in HCWs.

Methods: We analyzed the occupation, route of infection, symptoms, and vaccination history of all HCWs who tested positive for severe acute respiratory syndrome coronavirus 2 and worked in our hospital from November 2020 to March 2023. A logistic regression analysis was performed to examine the association between the presence of BA.5-adapted bivalent vaccination and symptoms.

Results: During the observation period, 531 HCWs became infected. Of these, 72 % were women, with a median age of 30 years. Nurses accounted for 57 % of the infected cases, and many of the infection routes were from family members. We examined the relationship between symptoms in 352 HCWs infected with the Omicron BA.5* variant and the number of vaccine doses. As the number of vaccine doses increased, the rate of fever decreased, while symptoms such as a runny nose and sore throat tended to increase. The logistic regression analysis showed that the rate of fever tended to decrease (odds ratio = 0.52, 95 % confidence interval: 0.26-1.01, p = 0.056) and that of a runny nose increased (odds ratio = 3.68, 95 % confidence interval: 1.17-10.6, p = 0.018) after BA.5-adapted bivalent vaccination.

Conclusion: This study shows that fever is reduced and mild symptoms are increased after BA.5-adapted bivalent vaccination in BA.5-infected HCWs. This result highlights the potential effectiveness of tailored vaccination strategies in the management of emerging COVID-19 variants.

Keywords: Bivalent; COVID-19; Omicron; Symptom; Vaccine.