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28th May 2021
COVID-19 mutations are to be expected and one particular lineage, B.1.617.2, first identified in India, has spread globally to at least 43 countries. As with all COVID-19 variants, a major concern for governments, is whether currently approved vaccines will provide sufficient protection against any such variants, especially given the fact that two recent variants, B.1.1.7 (first identified in the UK) and B.1.351 (identified in South Africa) have been shown to be resistant to sera from vaccinated individuals. Nevertheless, other data is more encouraging, suggesting that the BNT162b vaccine is effective against both variants of concern. The Indian variant of concern, B.1.617.2, has mutations in the spike protein which could potentially impact on the immune response. In a preprint study, a team from Public Health England, examined the effectiveness of two COVID-19 vaccines, BNT162b and ChAdOx1 against the variants of concern, B.1.1.7 and B.1.617.2. Data on the date of vaccinations and vaccine type were extracted from a national registry until 16th May 2021 and genomic sequencing was used to identify the proportion of different variants of concern present in positive PCR test samples.
A total of 12,675 sequenced cases were included in the analysis with 11,621 cases of B.1.1.7 and 1054 of B.1.617.2. Among individuals who had only received a single vaccine dose, overall efficacy was 33.5% against B.1.617.2 and 51.1% against cases of B.1.1.7. For the two vaccines, single vaccination with BNT162b had an efficacy of 49.2% against B.1.1.7 and only 33.2% against B.1.671.2. Similarly, the ChAdOx1 vaccine was only 51.4% effective against B.1.1.7 and 32.9% effective against B.1.671.2. However, once fully vaccinated, the overall vaccine efficacy was 86.8% against B.1.1.7 and 80.9% against B.1.617.2. The BNT162b was found to be the most effective with an efficacy of 93.4% and 87.9% against B.1.1.7 and B.1.617.2 respectively. However, while less effective, the ChAdOx1 still provided a satisfactory level of protection with a reported efficacy of 66.1% and 59.8% against B.1.1.7 and B.1.617.2 respectively.
The authors discussed how their findings indicated that only a single vaccine offered limited protection against these variants but that the efficacy was satisfactory once individuals were fully vaccinated, highlighting the importance of ensuring that all adults receive both doses.
Bernal JL, Andrews N, Gower C et al. Effectiveness of COVID-19 vaccines against B.1.617.2. variant. Public Health England 2021