Third COVID vaccine boosts antibodies that neutralize OmicronA third dose of COVID-19 vaccine successfully raises antibody levels that neutralize the Omicron variant, according to laboratory findings from UK scientists published yesterday in The Lancet.Researchers from the Francis Crick Institute (FCI) and the National Institute for Health Research (NIHR) UCLH Biomedical Research Centre used a high-throughput live SARS-CoV-2 neutralization assay to determine neutralizing antibody titers against Omicron, Alpha, and Delta variants in 620 serum samples from 364 people.
They found that antibodies generated in people who had received only two doses of either the Oxford-AstraZeneca vaccine or the Pfizer-BioNTech COVID vaccine were less able to neutralize the Omicron variant compared with the other two variants.They also found that antibody levels dropped off in the first 3 months following the second dose but that a third dose raised levels of antibodies that effectively neutralized the Omicron variant.
The study did not assess vaccine effectiveness, only antibody activity in the lab.Antibody levels against Omicron after a third Pfizer dose were similar to those reached against Delta after two doses.
Antibody levels were nearly 2.5 times higher against Omicron after three doses compared with after two.Higher levels of antibodies against Omicron were also found in people who previously had COVID-19 symptoms and received two doses of either vaccine, compared with those who had not had prior COVID-19 symptoms.Study author Emma Wall, MBChB, PhD, senior clinical research fellow at FCI and infectious disease specialist with UCLH, said in an FCI news release, "People who have queued outside vaccinations centres should be reassured