Antibodies generated from only two vaccine doses offer less protection against the Omicron variant

Researchers have found that booster vaccinations drive up antibody levels. A booster COVID-19 vaccination dose provides 2.5 times higher antibody levels against the Omicron variant of the virus than those provided by the initial two vaccinations.

These encouraging laboratory findings were shared by The Francis Crick Institute and the National Institute for Health Research (NIHR) UCLH Biomedical Research Centre.Researchers discovered that vaccination doses for COVID-19 successfully raise antibody levels that neutralise the Omicron variant. Meanwhile, antibodies generated in people who have received only two doses of either the Oxford/AstraZeneca vaccine, or the Pfizer/BioNTech vaccine, were less able to neutralise the Omicron variant.

The news will hopefully convince remaining sceptics that making a pilgrimage to a vaccination centre for a third dose is extremely important. Indeed, the findings showed antibody levels dropping in the first three months following the second dose, but that a third dose raised them to a level which was effective against Omicron, comparable to the protection reached against Delta (after two doses).

Levels of antibodies alone do not necessarily predict vaccine effectiveness, however, they are a very good indicator of protection against severe COVID-19.

“People who have queued outside vaccination centres should be reassured that a vaccine booster is the best way of protecting them from Omicron. And for people who haven’t yet had a booster or even a first dose, it’s not too late,” Dr Emma Wall, UCLH infectious diseases consultant and senior clinical research Fellow for the Legacy study, explained.

“This new variant can overcome the immune blockade put in place by two vaccine doses, but thankfully following the third dose, neutralising activity is robust in the vast majority of people. A third dose builds our defences higher, making it harder for the virus to cause severe COVID-19,” she added.

In conclusion, the study confirms that three doses of a COVID-19 vaccine are essential to boost antibodies to quantifiable levels, maximising an individual’s protection against severe disease and hospitalisation.