Researchers from Spain have recently evaluated the efficacy of vaccine developed by Pfizer-BioNTech (BNT162b2). Their findings have been published on a pre-print server and reveal that a 2-dose regimen of the vaccine is capable of providing almost 100% protection against SARS-CoV-2. BNT162b2 is a lipid nanoparticle-formulated, mRNA-based vaccine that contains prefusion stabilized, membrane-bound full-length spike protein of SARS-CoV-2 as an immunogen. A total of 2,590 healthcare workers were evaluated in the study.
The rate of new SARS-CoV-2 infections was examined at three-time points: one week before commencement of the vaccination; 1 – 4 weeks after the 1st dose; and one week after the 2nd dose. The prevalence of new infections among healthcare workers was compared to that of the general population in the same geographical region. During the study period, the vaccination rate in the community was less than 5%. The weekly rate of new SARS-CoV-2 infection was measured among healthcare workers using antigen test or CRP test. The study findings revealed that compared to a 7% reduction in the general population, the infection rate dropped by 63% among healthcare workers within 2 – 4 weeks after receiving the 1st vaccine dose.
Furthermore, a 99% reduction in new SARS-CoV-2 incidence was observed among healthcare workers after one week of receiving the 2nd vaccine dose, as compared to a 68% reduction in the community. Regarding COVID-19 vaccine response, there is evidence suggesting that individuals previously infected with SARS-CoV-2 exhibit strong immune responses to a single vaccine dose. The scientists believe that the robust protection observed in the study might be because 30% of the study participants were previously infected with SARS-CoV-2.
Ref Link: https://doi.org/10.1101/2021.03.24.21254238