The Pfizer vaccine may be effective in protecting against the Covid-19 variant that emerged in Manaus, Brazil, and has now been detected in the UK, a new study has found. Research has indicated that the vaccine also generated an antibody response against the UK variant and the strain first detected in South Africa. Neutralising antibodies The Covid-19 variants carry mutations which change the spike protein of the virus which it uses to attach to human cells, and may also have an impact on transmission. During laboratory tests against an engineered version of the virus, researchers found that levels of neutralising antibodies were generated against all three variants, although the level did vary between the strains. The antibody response was greatest against the original coronavirus variant and the more transmissible B117 variant first detected in Kent, according to the study published in the New England Journal of Medicine. The response was slightly lower against the P1 variant first identified in Brazil, and was lower still against the B151 variant first discovered in South Africa, researchers from the University of Texas Medical Branch and Pfizer found. Dr Peter English, consultant in communicable disease control and immediate past chairman of the BMA Public Health Medicine Committee, said: “Reassuringly, while the levels were lower for the P1 and B151 variants, they were still substantial, and likely to indicate that the vaccine will be effective. “The study looked in more detail at the precise mutations (the amino acid substitutions or deletions) that might affect vaccine efficacy, as we seem to have seen convergent evolution, where different lineages develop the same advantageous changes. “The authors remind us that these are laboratory findings, based on serum from only 15 individuals, and that other aspects of the immune response, such as T-cell (cellular) immunity are likely to be important in real-world vaccine efficacy, and the vaccine ‘elicits CD8+ T-cell responses that recognise multiple variants’. “Taken together, these findings indicate that this vaccine is likely to be effective against the variants studied, although precisely how effective they are in the real world will require data on the vaccine’s actual effect in populations, not just in laboratory studies such as this one.” He added: “This study looked only at the neutralising antibody levels generated in the serum of people who had received two doses of the Pfizer-BioNTech vaccine. “In itself, this study does not provide any evidence about other vaccines. However, we know that other available vaccines use precisely the same antigen, albeit delivered in different ways. “Given this, it is highly plausible that other vaccines will have similar efficacies against these variant strains but we do not know this for certain.”
