A cross-sectional study of SARS-CoV-2 antibodies among healthcare workers in a tertiary care hospital in Taiwan: implications for protection against the Omicron variants

Chang-Hua Chen; Day-Yu Chao; Chew-Teng Kor; Su-Feng Kuo; Jen-Shiou Lin; Huei-Wen Lai; Yen-Tze Liu; Ching-Hsiung Lin; Mu-Kuan Chen

doi:10.1186/s12879-024-09411-z

A cross-sectional study of SARS-CoV-2 antibodies among healthcare workers in a tertiary care hospital in Taiwan: implications for protection against the Omicron variants

BMC Infect Dis. 2024 May 27;24(1):529. doi: 10.1186/s12879-024-09411-z.

Authors

Chang-Hua Chen^{1

2

3}, Day-Yu Chao⁴, Chew-Teng Kor^{5

6}, Su-Feng Kuo⁷, Jen-Shiou Lin⁷, Huei-Wen Lai⁸, Yen-Tze Liu^{9

10}, Ching-Hsiung Lin¹¹, Mu-Kuan Chen^{12

13}

Affiliations

¹ Division of Infectious Diseases, Department of Internal Medicine, Changhua Christian Hospital, Changhua; No.135, Nanxiao St., Changhua City, Changhua County, 50006, Taiwan. [email protected].
² Department of Post-Baccalaureate Medicine, College of Medicine, National Chung-Hsing University, No. 145 Xingda Rd., South Dist, Taichung City, 40227, Taiwan. [email protected].
³ Doctoral Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, No. 145 Xingda Rd., South Dist., Taichung City, 40227, Taiwan. [email protected].
⁴ Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung-Hsing University, No. 145 Xingda Rd., South Dist, Taichung City, 40227, Taiwan.
⁵ Big Data Center, Changhua Christian Hospital, No.135, Nanxiao St., Changhua City, Changhua County, 50006, Taiwan.
⁶ Institute of Statistics and Information Science, National Changhua University of Education, Changhua County, No.1, Jinde Rd, Changhua City, Changhua County, 50074, Taiwan.
⁷ Clinical Microbiology Laboratory, Changhua Christian Hospital, No.135, Nanxiao St., Changhua City, Changhua County, 50006, Taiwan.
⁸ Center for Infection Prevention and Control, Changhua Christian Hospital, No.135, Nanxiao St., Changhua City, Changhua County, 50006, Taiwan.
⁹ Department of Post-Baccalaureate Medicine, College of Medicine, National Chung-Hsing University, No. 145 Xingda Rd., South Dist, Taichung City, 40227, Taiwan.
¹⁰ Department of Family Medicine, Changhua Christian Hospital, No.135, Nanxiao St., Changhua City, Changhua County, 50006, Taiwan.
¹¹ Division of Chest Medicine, Department of Internal Medicine, Changhua Christian Hospital, No.135, Nanxiao St., Changhua City, Changhua County, 50006, Taiwan.
¹² Department of Post-Baccalaureate Medicine, College of Medicine, National Chung-Hsing University, No. 145 Xingda Rd., South Dist, Taichung City, 40227, Taiwan. [email protected].
¹³ Department Of Otorhinolaryngology - Head & Neck Surgery, Changhua Christian Hospital, No.135, Nanxiao St., Changhua City, Changhua County, 50006, Taiwan. [email protected].

Abstract

Background: Taiwan, deeply impacted by the 2003 SARS outbreak, promptly implemented rigorous infection control and prevention (ICP) measures in January 2020 to combat the global COVID-19 pandemic. This cross-sectional serologic study was conducted among healthcare workers (HCWs) in a tertiary care hospital in Taiwan from August 1, 2022, to February 28, 2023. The study aimed to assess HCWs' antibody responses to COVID-19 vaccination against Omicron subvariants BA.1, BA.4, and BA.5, considering variations in prior infection. Additionally, it evaluated the effectiveness of ICP and vaccination policies within the hospital setting in Taiwan.

Methods: A cross-sectional serology study was conducted in Taiwan to investigate the seroprevalence rates of Omicron subvariants BA.1, BA.4, and BA.5 among HCWs. A total of 777 HCWs participated in this study. A structured questionnaire was collected to obtain the epidemiological characteristics and risk factors for potential exposure. Enzyme-linked immunosorbent assay was used to detect antibody responses. Serum samples were selected for protection against Omicron subvariants BA.1, BA.4, and BA.5 by using a pseudotyped-based neutralization assay.

Results: More than 99% of the participants had received SARS-CoV-2 vaccination. Overall, 57.7% had been infected with SARS-CoV-2, with some being asymptomatic. The SARS-CoV-2 Anti-Spike S1 protein IgG (Anti-S) distribution was 40,000 AU/mL for 20.2% (157/777) of participants, with a mean ± standard deviation of 23,442 ± 22,086. The decay curve for Anti-S was less than 20,000 AU/ml after 120 days. The probability curve of 50% neutralization showed an Anti-S of 55,000 AU/ml. The optimum Anti-S was 41,328 AU/mL (equal to 5,869 WHO's standard BAU/mL), with 86.1% sensitivity and 63.5% specificity.

Conclusions: In this significant study, 20.2% of HCWs achieved seroprotection against Omicron subvariants BA.1, BA.4, and BA.5. Their immunity against Omicron subvariants was further reinforced through recommended vaccinations and the development of natural immunity from SARS-CoV-2 exposure, collectively enhancing their protection against Omicron.

Keywords: COVID-19; Healthcare workers; Omicron variant; SARS-CoV-2; Serology.

MeSH terms

Adult
Antibodies, Viral* / blood
COVID-19 Vaccines / administration & dosage
COVID-19 Vaccines / immunology
COVID-19* / epidemiology
COVID-19* / immunology
COVID-19* / prevention & control
Cross-Sectional Studies
Female
Health Personnel* / statistics & numerical data
Humans
Male
Middle Aged
SARS-CoV-2* / immunology
Seroepidemiologic Studies
Taiwan / epidemiology
Tertiary Care Centers*

A cross-sectional study of SARS-CoV-2 antibodies among healthcare workers in a tertiary care hospital in Taiwan: implications for protection against the Omicron variants

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