Pfizer vaccines not as effective on variants: Lancet

New Delhi: The Pfizer-BioNTech vaccine has been found to be not as effective against the Delta variant as it is with the original strain, reveals a new study in The Lancet journal.

Published as a research letter in The Lancet on Thursday, the study said that the antibody did have a less neutralising effect on variants for those who have received just a single jab. After being administered the first dose of Pfizer-BioNTech, 79 per cent of people had a quantifiable neutralising antibody response against the original strain; however, the effect dropped to 50 per cent for Alpha variant (B.1.1.7), 32 per cent for Delta variant (B.1.6172) and 25 per cent for Beta variant (B.1.351). Levels of these antibodies, which decline over time, are lower with increasing age, while no correlation was observed for sex or body mass index, the study shows.

Researchers from the Francis Crick Institute and the National Institute for Health Research (NIHR) UCLH Biomedical Research Centre in the UK in their study state that lower neutralising antibody levels may still be associated with defending against Covid19.

"This virus will likely be around for some time to come, so we need to remain agile and vigilant. Our study is designed to be responsive to shifts in the pandemic so that we can quickly provide evidence on changing risk and protection," pointed out Emma Wall, UCLH Infectious Diseases consultant.

"The most important thing is to ensure that vaccine protection remains high enough to keep as many people out of hospital as possible. And our results suggest that the best way to do this is to quickly deliver second doses and provide boosters to those whose immunity may not be high enough against these new variants," she added.

The study favours reducing the dose gap between vaccines as people are less likely to develop antibody levels against the Delta variant, which is dominant in India, after the first dose. Antibodies of around 250 healthy volunteers, who were immunised with one or two doses of the Pfizer-BioNTech anti-Covid19 vaccine, were analysed for up to three months after their first dose. The researchers then tested the ability of antibodies to hinder the entry of the virus into cells or "neutralising antibodies" against five mutated strains.

The research will be further carried on to participants vaccinated with the Oxford-AstraZeneca vaccine.