Pfizer-BioNTech vaccine recipients have lower antibody levels targeting the Delta variant

Research part of SARS-CoV-2 Legacy study involving UCL, the Crick and UCLH - Levels of antibodies in the blood of vaccinated people that are able to recognise and fight the new SARS-CoV-2 Delta variant first discovered in India (B.1.617.2) are, on average, lower than those against variants previously circulating in the UK, finds a new study involving UCL. The results of the laboratory data, published as a research letter* in The Lancet , also show that levels of these antibodies are lower with increasing age and that levels decline over time, providing additional evidence in support of plans to deliver a vaccination boost to vulnerable people in the Autumn. And, the researchers support current plans to reduce the dose gap between vaccines since they found that after just one dose of the Pfizer-BioNTech vaccine, people are less likely to develop antibody levels against the B.1.617.2 (Delta) variant as high as those seen against the previously dominant B.1.1.7 (Alpha) variant, first found in Kent. Although laboratory results such as this 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. The laboratory data used in the study is from the Francis Crick Institute and the National Institute for Health Research (NIHR) UCLH Biomedical Research Centre.