The effect of the third dose of the BNT162b2 vaccine on anti-SARS-CoV-2 spike antibody levels in healthcare workers with and without COVID-19 infection

AIM: A third (booster) dose of the anti-SARS-CoV-2 vaccine became necessary due to the observed decrease in anti-SARS-CoV-2S antibody levels over time, new mutations, and low global vaccination rates. In this study, anti-SARS-CoV-2S antibody levels were measured (ECLIA assay) in 50 healthcare workers with and without a history of COVID-19 infection to determine the humoral immune response to the third dose of the BNT162b2 vaccine. METHODS: Antibody levels were determined in the blood serum, and blood was sampled for analysis 20–40 days after the administration of the booster dose. RESULTS: A greater increase in anti-SARS-CoV-2S antibody titers was noted in persons without a history of infection, but antibody levels continued to be higher in previously infected individuals when the results were adjusted for age, gender, BMI, type of work, and presence of comorbidities. CONCLUSION: The results of this study can be used to improve the vaccination strategy for the general population. KEY MESSAGES: Three doses of the vaccine BNT162b2 strongly stimulate the immune system to produce anti-SARS-CoV-2s antibodies, especially in people with a previous infection COVID-19. Age, gender, and BMI may be associated with different humoral immune response to the BNT162b2 vaccine.