People who have received the Pfizer vaccine have lower antibody levels that target the Delta variant, first discovered in India, than those that targeted previously circulating variants in the UK, new data suggests.

The study found that after just one dose of the Pfizer jab, people are less likely to develop antibody levels against the Delta variant, as high as those seen against the previously dominant Alpha variant, which was first discovered in Kent.

The study, from the Francis Crick Institute and the National Institute for Health Research, suggests the level of such antibodies are lower with older age and that the levels decline over time.

It is believed that this research provides additional evidence in support of a vaccination boost to vulnerable people in the autumn.

The new laboratory data also supports current plans to reduce the dose gap between vaccines.

Emma Wall, UCLH Infectious Diseases consultant and senior clinical research fellow for the Legacy study, said: “Our study is designed to be responsive to shifts in the pandemic so that we can quickly provide evidence on changing risk and protection.

“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.”

According to the research, in people who had received two doses of the Pfizer vaccine, levels of neutralising antibodies were more than five times lower against the Indian variant when compared to the original strain, upon which current vaccines are based.

This antibody response was even lower in people who had only received one dose.