According to research published in The Lancet journal, people completely vaccinated with the Pfizer-BioNTech vaccine are anticipated to have more than five times lower levels of neutralizing antibodies against the Delta variation initially detected in India compared to the original strain.

The study also found that levels of these antibodies, which can recognize and fight the virus, decrease with age and fall over time, offering additional evidence in support of plans to give vulnerable people a booster dosage.

It backs up the current UK plans to close the vaccine dose gap, as researchers discovered that people are less likely to develop antibody levels against the B.1.617.2 variant as high as those seen against the previously dominant B.1.1.7 (Alpha) variant, which was first discovered in Kent, after just one dose of the Pfizer-BioNTech vaccine.

Researchers from the Francis Crick Institute in the United Kingdom led the team, which emphasized that antibody levels alone do not predict vaccine success, and that prospective population studies are required. They believe that lower levels of neutralizing antibodies are still linked to protection against COVID-19.

The researchers looked at antibodies in the blood of 250 healthy patients who had one or two doses of the Pfizer-BioNTech Covid-19 vaccine, three months after their first dosage.

The researchers examined antibodies' ability to stop virus entry into cells, sometimes known as 'neutralising antibodies,' against five different SARS-CoV-2 types.