Pfizer jab produces less antibodies against Delta variant: Report

People fully vaccinated with two doses of the Pfizer-BioNTech vaccine are likely to have more than five times lower levels of neutralising antibodies against the Delta variant (B16172) when compared to the original strain, according to new laboratory data that supports Pfizer’s plans to deliver booster shots in Autumn.

This antibody’s response was even lower in people who had only received one dose. After a single dose of Pfizer-BioNTech, 79 per cent of people had a quantifiable neutralising antibody response against the original strain, but this fell to 50 per cent for Alpha variant (B117), 32 per cent for Delta variant (B16172) and 25 per cent for Beta variant (B1351), showed the study, published as a Research letter in The Lancet on Thursday.

The results also show that levels of these antibodies are lower with increasing age and that levels decline over time, while no correlation was observed for sex or body mass index.

Although laboratory results such as these are needed to provide a guide as to how the virus might be evolving to escape the first generation of vaccines, levels of antibodies alone do not predict vaccine effectiveness and prospective population studies are also needed. Lower neutralising antibody levels may still be associated with protection against Covid-19, said researchers from the Francis Crick Institute and the National Institute for Health Research (NIHR) UCLH Biomedical Research Centre in the UK.

“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,” said Emma Wall, UCLH Infectious Diseases consultant.