ภาควิชาอายุรศาสตร์

Background: The first COVID-19 vaccination campaign in Thailand began in April 2020, with healthcare
workers receiving two doses of inactivate .

Background: The first COVID-19 vaccination campaign in Thailand began in April 2020, with healthcare
workers receiving two doses of inactivated COVID-19 vaccine (CoronaVac). However, the emergence of
the delta and omicron variants raised concerns about vaccine effectiveness. The Thai Ministry of Public
Health provided the first booster dose (third dose) and second booster dose (fourth dose) of the mRNA
vaccine (BNT162b2) for healthcare workers. This study investigated the immunity and adverse reactions
elicited by a heterologous second booster dose of BNT162b2 after a two-dose CoronaVac vaccination for
COVID-19 in healthcare workers of the Faculty of Medicine, Naresuan University.
Methods: IgG titres against the SARS-CoV-2-spike protein were measured four and 24 weeks after the
second booster dose of BNT162b2 in the study participants. Adverse reactions were recorded during
the first three days, four weeks and 24 weeks after the second booster dose of BNT162b2.
Results: IgG against the SARS-CoV-2-spike protein was positive (>10 U/ml) in 246 of 247 participants
(99.6 %) at both four and 24 weeks after the second booster dose of BNT162b2. The median specific
IgG titres at four and 24 weeks after the second booster dose of BNT162b2 were 299 U/ml (min: 2,
max: 29,161) and 104 U/ml (min: 1, max: 17,920), respectively. The median IgG level declined significantly
24 weeks after the second booster dose of the BNT162b2 vaccine. Of the 247 participants, 179
(72.5 %) experienced adverse reactions in the first three days after the second booster dose of
BNT162b2. Myalgia, fever, headache, injection site pain and fatigue were the most common adverse reactions.
Conclusion: This study demonstrated that a heterologous second booster dose of BNT162b2 after two
doses of CoronaVac induced elevated IgG against the SARS-CoV-2-spike protein and caused minor
adverse reactions in healthcare workers of the Faculty of Medicine, Naresuan University.
This study was registered as Thailand Clinical Trials No. TCTR20221112001.

พุทธชินราชเวชสาร ปีที่ 31 ฉบับที่ 2 พฤษภาคม – สิงหาคม 255 .

พุทธชินราชเวชสาร ปีที่ 31 ฉบับที่ 2 พฤษภาคม – สิงหาคม 2557