Omicron reduces vaccine protection in Oxford study

The omicron variant reduced the protection provided by two doses of the COVID vaccines developed by Pfizer Inc. and AstraZeneca Plc, as feared, increasing the risk of contagion, researchers revealed.

Blood samples collected from people vaccinated with doses of one of the two pharmaceutical companies and tested against the new variant showed a significant drop in neutralizing antibodies – an indicator of protection – particularly compared to the delta variant, researchers from Oxford University in a report.

The results echo other recent findings that emphasize the need for booster doses, especially amid the evidence for omicron’s ability to drive massive numbers of infections.

However, the scientists could not answer another key question: about the ability of vaccines to prevent severe disease. The new mutation has raised concern around the world, but reports from South Africa, where it was first detected, suggest that cases so far appear to be milder than during previous waves.

The impact of the omicron variant should be better documented in a few more weeks, making it clear whether new doses are necessary, according to Teresa Lambe, one of the creators of the vaccine Astra developed in conjunction with Oxford.

“We are hopeful that the current vaccine will protect against severe disease and hospitalization, and that is certainly what we have seen before with other variants of concern.“Lambe told the press. “We and other vaccine manufacturers are in a position where, if a vaccine is needed for a new variant, we can move fast. “.

Meanwhile, the rise in infections alone could put hospitals under pressure in places like the UK. Gavin Screaton, head of Oxford’s division of medical sciences and lead author of the report, called for maintaining the “Caution, as increased numbers will continue to place a significant burden on health care systems”.

The researchers observed a nearly 30-fold decrease in neutralizing antibodies to the omicron variant after two doses of the Pfizer vaccine compared to the delta variant. The impact with the Astra vaccine was similar. The authors also found evidence that some participants failed to neutralize the virus at all.

Neutralizing antibodies are just one branch of the immune system defense, and scientists are now looking at how T cells respond to the variant. The conclusions of these studies are expected to be ready in the next few weeks.

Blood samples were taken from the Oxford-led Com-Cov2 study that looked at how combining vaccines (“mix and match”) with different intervals affects the immune response to COVID-19. The findings on the omicron variant were based primarily on those volunteers who had received two doses of the same vaccine, the researchers said at a news conference on Monday.

The data was released on medRxiv, a site that reports unpublished medical research results, and was peer-reviewed.