Antibody Response after BNT162b2 Vaccination in Healthcare Workers Previously Exposed and Not Exposed to SARS-CoV-2

Abstract

The Pfizer/BioNtech Comirnaty vaccine (BNT162b2 mRNA COVID-19) against SARS-CoV-2 is currently in use in Italy. Antibodies to evaluate SARS-CoV-2 infection prior to administration are not routinely tested; therefore, two doses may be administered to asymptomatic previously exposed subjects. The aim of this study is to assess if any difference in antibody concentration between subjects exposed and not exposed to SARS-CoV-2 prior to BNT162b2 was present after the first dose and after the second dose of vaccine. Data were retrospectively collected from the clinical documentation of 337 healthcare workers who underwent SARS-CoV-2 testing before and after BNT162b2. Total anti RBD (receptor-binding domain) antibodies against SARS-CoV-2′s spike protein were measured before and 21 days after the first dose, and 12 days after the second dose of BNT162b2. Twenty-one days after the first dose, there was a statistically significant difference in antibody concentration between the two groups, which was also maintained twelve days after the second dose. In conclusion, antibody response after receiving BNT162b2 is greater in subjects who have been previously exposed to SARS-CoV-2 than in subjects who have not been previously exposed to the virus, both after 21 days after the first dose and after 12 days from the second dose. Antibody levels, 21 days after the first dose, reached a titer considered positive by the test manufacturer in the majority of subjects who have been previously infected with SARS-CoV-2. Evaluating previous infection prior to vaccination in order to give the least effective number of doses should be considered.

Factors Influencing Level and Persistence of Anti SARS-CoV-2 IgG after BNT162b2 Vaccine: Evidence from a Large Cohort of Healthcare Workers

“…Considering the impact of previous infection with SARS-CoV-2 on serological response, as previously reported [ 5 , 19 , 27 , 28 , 29 , 30 , 31 , 32 ], we confirmed that this was associated with significantly higher antibody levels, with approximately half of the subjects displaying values exceeding the upper limit of detection and a remaining 20% in the immediately lower quintile. This finding is relevant, considering that our study was performed at 4–5 months post-vaccination, whereas most studies evaluated individuals at 3 to 7 weeks post-vaccination.…”

Safety and Immunogenicity of a Single Dose of BNT162b2 COVID-19 mRNA Vaccine in a Warfarin-Treated Protein S Deficient Patient: A Case Report and Literature Review

“…This finding is concordant with previous reports that indicated the seroconversion rate was highest at 21 days after the first dose of the BNT162b2 mRNA vaccine [13,14]. However, the anti-S antibody level in our patient displayed a tendency to be lower than the median value of antibodies concentration found in infection-naïve individuals on day 21 post-vaccination [13,15]. Although the involvement of PS in the development of host humoral immune response remains unclear, previous studies have shown that PS signaling through TAM receptor (MERTK) on lymphocyte T cells plays a role in inducing proliferation, cytokines release, and differentiation into memory cells [16,17].…”

High baseline expression of IL-6 and IL-10 decreased CCR7 B cells in individuals with previous SARS-CoV-2 infection during BNT162b2 vaccination

“…Although this more intense response in the production of antibodies has been previously reported by (14,15,18,19), it is clear that there may be more differences in the immune response mounted by individuals with natural infection and without previous natural disease, and some of them could even help to explain the disparity in the humoral response. We evaluated a panel of cytokines and cell populations in peripheral blood and the follow-up to identify these differences.…”