In real-world pandemic situations, most COVID-19 vaccines have shown equivalent efficacy against the original SARS-CoV-2 and variant B.1.1.7, which was first identified in the UK. However, in general, those induced by natural infection showed lower efficacy in neutralizing variants B.1.351 and were identified for the first time in South Africa. and spike mutations E484K and K417T in the P1 variant has been attributed to their immune evasion abilities. An original nationwide case-control study conducted in France evaluated the efficacy of mRNA-based COVID-19 vaccines against the SARS-CoV-2 coronavirus and its variants, including B.1.1.7 (Alpha), B.1.351 (Beta) and P1 (Gamma). In real-life pandemic situations, the two-dose regimen of mRNA vaccines showed equivalent protective efficacy against the original virus and the Alpha variant and slightly reduced efficacy against the Beta and Gamma variants. This nationwide case-control study was conducted on 7,288 adults infected with the original SARS-CoV-2 virus, 31,313 with the Alpha variant, 2,550 with the Beta variants. Additionally, 3,644 uninfected individuals were included as controls.
All participants were asked to complete an online review on a questionnaire collected information on socio-demographic characteristics, information on pre-existing socio-demographic characteristics, recent SARS-CoV-2 test results, recent activity-related viral exposures, and vaccination details. Specifically, gliNs aimed to underestimate the efficacy of two mRNA vaccines BNT162bPfizer / BioTech) and mRNA-1273 (Moderna), in the context of the world’s pandemic. However, due to the lack of information on vaccination, they could determine the effectiveness of two vaccines. Based on the survey results, susceptibility to acquiring B.1.1.7 or B.1.351 / P1 infection was relatively higher among male participants, non-health workers and those with higher education levels.A higher susceptibility to acquisition of B.1.351 / P1 infection was observed among participants even after receiving two doses of mRNA vaccines. A recent history of PCR-confirmed SARS-CoV-2 infection (2-6 months) was found to be 83% to 88% protective against all viral variants tested.
Similarly, a relatively distant history of SARS-CoV-2 infection (more than 6 months) was found to be 74-84% protective against all viral variants. The protective efficacy of the mRNA vaccines 7 days after the 2nd dose was found to be 88% against the original SARS-CoV-2, 86% against the Alpha variant and 77% against the Beta / Gamma variants. This is not the only study to have investigated the effect of vaccines on variants: another research investigated the effect of the Moderna vaccine on the Alpha and Beta variants, based on data collected in Qatar, where the two variants of the coronavirus. The weekly rounds of random testing collected 3,924 identifying samples, which provide approximate for Alpha and Beta in the population of 66.4% and 24.7%, respectively. Against variant B.1.1.7, defined by those with positive buffer B.1.1.7, the vaccine generated a negligible immune response for two weeks after the first dose, while reaching 81.6% and 94.4 % in weeks three and four. The second dose then induced immunity of 99.2% for two weeks, rising to 100% for at least two subsequent weeks.
Likewise, the vaccine has a poor immune response for the first two weeks after the first dose against the generation variant of B.1.351, reaching 47.9% and 73.7% in weeks three and four. However, the second dose of the vaccine caused an increase in efficacy to 96.4% due to more weeks or more later. Variants B.1.1.7 and B.1.351 SARS-CoV-2 also experienced similar declines in disease severity or likelihood of death following vaccine administration, with little effect in weeks one and two, rapidly increasing to 70.3% and 92.1% efficacy in weeks three and four. Two or more weeks after the second dose, the vaccine efficacy in limiting disease severity reached 95.7%, with the vaccine efficacy against symptomatic infection 98.6%. The efficacy of the vaccine against asymptomatic infection, in the absence of infection, was calculated as 92.5%. The development of protection against the Beta variant showed a slower build-up rate than the Alpha variant.
Furthermore, most protection is provided after a single dose is administered after sufficient time, which is supported by other studies and suggests that a delayed or absent second dose may be a valid vaccine-sparing strategy. In any case, these results suggest that the vaccine maintains good efficacy against variants B1.1.7 and B.1.351 in all respects, comparable to that observed against the original SARS-CoV-2.
- edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
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