Affiliations 

  • 1 Universiti Putra Malaysia, Faculty of Medicine & Health Sciences, Department of Pathology, Selangor, Malaysia
  • 2 Hospital Pengajar Universiti Putra Malaysia, Department of Medical Microbiology, Universiti Putra, Selangor, Malaysia
  • 3 Hospital Pengajar Universiti Putra Malaysia, Department of Pathology, Universiti Putra, Selangor, Malaysia
  • 4 Hospital Pengajar Universiti Putra Malaysia, Nursing Unit, Universiti Putra, Selangor, Malaysia
  • 5 Institute for Public Health, Centre for Communicable Diseases Research, Ministry of Health, Malaysia
  • 6 Universiti Putra Malaysia, Faculty of Medicine and Health Sciences, Department of Biomedical Sciences, Selangor, Malaysia
  • 7 Universiti Putra Malaysia, Faculty of Medicine and Health Sciences, Department of Community Health, Selangor, Malaysia
  • 8 Universiti Putra Malaysia, Faculty of Medicine & Health Sciences, Department of Ophthalmology, Selangor, Malaysia. mmi@upm.edu.my
Med J Malaysia, 2023 Jan;78(1):20-24.
PMID: 36715186

Abstract

INTRODUCTION: Healthcare workers (HCWs) were among the first to be fully vaccinated against SARS-CoV-2. However, the antibody responses to the vaccines and potential decline among Malaysian HCW are still unclear. The objective of this study is to follow-up anti-S antibody levels among HCW vaccinated with mRNA vaccine (BTN162b2) and inactivated vaccine (CoronaVac).

MATERIALS AND METHODS: Plasma samples were collected prevaccination, 2 weeks and 6 months post-vaccination and tested for total immunoglobulin levels using ELISA method.

RESULTS: A small percentage of HCW (2.2%, 15/677) had elevated anti-S antibody levels in their pre-vaccination plasma samples (median 20.4, IQR 5.8), indicating that they were exposed to SARS-CoV-2 infection prior to vaccination. The mRNA vaccine significantly increased anti-S levels of both previously infected and uninfected individuals to saturation levels (median 21.88, IQR.0.88) at 2 weeks postsecond dose of the vaccine. At 6 months post-vaccination, the antibody levels appeared to be maintained among the recipients of the mRNA vaccine. However, at this time point, anti-S antibody levels were lower in individuals given inactivated vaccine (median 20.39, IQR 7.31, n=28), and interestingly, their antibody levels were similar to anti-S levels in pre-vaccination exposed individuals. Antibody levels were not different between the sexes.

CONCLUSION: Anti-S levels differ in individuals given the different vaccines. While further study is required to determine the threshold level for protection against SARSCoV- 2, individuals with low antibody levels may be considered for boosters.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.