1 ). Table 1 Geometric mean concentrations (GMC) of anti-SARS-CoV-2 RBD IgG 14?days post-immunization after the first and second dose of the BNT162b2 vaccine along with fold changes thereof. due to compromised vaccine effectiveness [3] and increased risk of new variant emergence [4], the latter gains momentum [5]. We sought to assess the viability of these alternatives, conducting a phase IV immunogenicity study around the BNT162b2 mRNA Covid-19 vaccine. Launched by Pfizer-BioNTech, this vaccine was the first to receive FDA and EMA approval, displaying 95% efficacy in pre-marketing clinical trials [6]. Latest real-world evidence confirms its high effectiveness, reaching 94% for symptomatic Covid-19 [7] and attests to its strong immunogenicity in 92% of recipients [8], [9]. Antibody generation was found significantly pronounced among previously-infected convalescent subjects in the aftermath of the first dose, questioning the necessity of a booster dose to Astilbin those individuals [2], [5]. The aim of the present study was to provide a comprehensive analysis of the humoral immune responses of 401 vaccinees to both doses of the BNT162b2, laying emphasis on certain subgroups of interest, including seniors and seropositive individuals. 2.?Materials and methods 2.1. Enrolment and methods In our study, we measured the generation of antibodies elicited 14?days post-injection of each dose of the BNT162b2 mRNA vaccine in Greek healthcare workers aged 20C67. In the first phase of our study, antibody levels were monitored in a total of 425 participants that received the first dose of the vaccine Astilbin [9]. Our final sample consisted of 401 subjects that were immunized with both doses of the vaccine, since 24 vaccinees did not show up for the second antibody measurement 14?days after the second dose. Our study populace included both uninfected (n?=?342) and previously-infected convalescent subjects (n?=?59) with PCR-confirmed SARS-CoV-2 contamination occurring 1 to 4.5?months prior to immunization. We employed the SARS-CoV-2 IgG II Quant assay around the Architect Ntrk2 System (Abbott, Sligo, Ireland) to monitor titers of neutralizing IgG against the receptor-binding domain name (RBD) of the S1 subunit of the spike protein in participant-derived serum samples. 2.2. Ethics approval The study protocol was examined and approved by the Scientific Committee of the G. Gennimatas General Hospital (protocol number:1/13.1.2021). All subjects agreed to voluntarily participate in the study. 2.3. Statistical analysis Stata 16.1 (Stata Corp. LLC, College Station, TX) was utilized for data analysis. Descriptive statistics included proportions of immunogenic response and Astilbin geometric means of concentration (GMC) of RBD-specific IgG (AU/ml) and the corresponding 95% confidence intervals (95% CI) of each analyzed group stratified by gender, age, and history of previous SARS-CoV-2 infection. Impartial samples t-tests were used to assess differences in log10 IgG levels and fold changes among gender- and SARS-CoV-2 contamination history groups. Paired samples t-tests were employed for the corresponding comparisons between first and second dose. One-way ANOVA with Sidak correction for multiplicity was employed for the comparison of age groups. P-values less than 0.05 were considered statistically significant. 3.?Results After the first dose, titers were found to fluctuate with age, marking a significant decline in the 50C60 age group, while dropping even further in participants aged over 60 (p? ?0.001). This difference was surmounted following the second dose, as the titer fold-changes recorded were significantly higher in the 50C60 age group, while escalating in subjects aged over 60 (p? ?0.001). Eventually, satisfactory levels of neutralizing antibodies were detected in all of our study participants in the aftermath of the second dose, regardless of age (Table 1 , Fig. 1 ). Table 1 Geometric imply concentrations (GMC) of anti-SARS-CoV-2 RBD IgG 14?days post-immunization after the first and second dose of the BNT162b2 vaccine along with fold changes thereof. P values are based on log10 transformed values..
