Abstract
The efficacy of SARS-CoV-2 mRNA-based vaccines in preventing COVID-19 disease has been extensively demonstrated; however, it is of uttermost importance to acquire knowledge on the persistence of immune-protection both in terms of levels of neutralizing antibodies and specialized memory cells. This can provide important scientific basis for decisions on the need of additional vaccine doses and on when these should be administered thus resulting in an improvement in vaccination schedules. Here, we briefly report the changes in antibody levels and cellular immunity following BNT162b2 administration. We show an important fall in anti S1-Spike antibodies in BNT162b2 vaccinated subjects overtime, paralleled by a contextual consolidation of specific spike (S) T-cells, mainly of the CD8+ compartment. Contrariwise, CD4+ S-specific response shows a considerable interindividual variability. These data suggest that the well-known antibody drop in vaccinated subjects is replaced by memory cell consolidation that can protect from severe adverse effects of SARS-CoV-2 infection.
Highlights
The efficacy of SARS-CoV-2 mRNA-based vaccines in terms of reduction of infection spreading and more importantly in terms of reduction of disease severity, hospitalizations, and death has been widely demonstrated [1,2,3,4,5,6].the duration of the immune protection following vaccination is still not well defined
We observed a rapid increase of IgG levels following administration of the second dose as compared to CTRL (p < 0.0001), and a dramatic fall after 150 days (p < 0.0001) to Dunn’s multiple comparisons post-test
Levels of IgG remained positive in 100% of the tested individuals and were significantly higher than controls after 150 days from the second dose (p < 0.0001)
Summary
The efficacy of SARS-CoV-2 mRNA-based vaccines in terms of reduction of infection spreading and more importantly in terms of reduction of disease severity, hospitalizations, and death has been widely demonstrated [1,2,3,4,5,6]. Previous studies have shown that the SARS-CoV-2 (BNT162b2) booster vaccination produces high levels of neutralizing antibodies which, as expected, decrease over time [6,7,9,10,11], while it has been demonstrated that T-cell immunity has a key role for a durable immune memory response as protection against SARS-CoV-2 infection, and memory T-cell responses can persist for many years [12,13,14]. Taking into consideration that antibodies and memory T-cells, both CD4+ and CD8+, are all involved in protective immunity for both humoral and cell-mediated immune responses against COVID-19, we assessed the longitudinal stability of SARS-CoV-2 T responses in BNT162b2 vaccinated adults as well as the changes in anti-SARS-CoV-2 IgGs, 15 and 150 days following the boost with the second dose of vaccine [11]
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