Neutralizing antibody responses in healthcare personnel after three doses of mRNA BNT162b2 vaccine and association with baseline characteristics and past SARS-CoV-2 infection

Aim: To estimate neutralizing antibody (NAb) immunity against SARS-CoV-2 in 739 healthcare personnel (HCP) vaccinated with three doses of BNT162b2 mRNA vaccine.Methods: Serum samples were collected at 3, 6, and 9 months after the second vaccine dose and at 7- 55 days after the third dose. Samples were tested for NAbs against SARS-CoV-2 receptor binding domain.Results: The mean inhibition rates at 3, 6, and 9 months after the second dose were 86.33%, 73.38%, and 61.18%, and increased to 95.57% after the booster dose. Younger HCP and HCP with past SARS-CoV-2 infection had higher inhibition rates while there was an inverse correlation between NAb levels and comorbidities or tobacco use (p-values < 0.001). Increased NAb titers were also noticed in women (p -value = 0.033), especially at the end of the 9-month study period.Conclusion: NAb levels increased considerably after a booster mRNA vaccine dose. Host factors and past SARS-CoV-2 infection influence NAb titers.(c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study aimed to assess the neutralizing antibody immunity against SARS-CoV-2 in healthcare personnel vaccinated with three doses of the BNT162b2 mRNA vaccine. The results showed that the neutralizing antibody levels significantly increased after receiving the booster dose of the vaccine. Younger individuals and those with previous SARS-CoV-2 infection had higher antibody levels, while there was an inverse correlation between antibody levels and comorbidities or tobacco use. At the end of the study period, an increase in neutralizing antibody titers was observed in women.