Covid booster jabs are likely to protect against Omicron variant, study suggests

3 December 2021, 06:58 | Updated: 7 June 2023, 08:56

Existing coronavirus booster vaccines could offer good protection against the Omicron variant of coronavirus, experts behind a major new study have suggested.

The jabs could provide an immune response to the new "concerning" Omicron variant - with Pfizer and Moderna found to give the best overall booster response, according to the Government-funded trial. 

A team studying the effects of third doses said the body's T cell immune response after a booster shot is such that it may provide protection from hospital admission and death.

The research, undertaken by the University Hospital Southampton, also backs up the UK's decision to offer Pfizer or Moderna as a third shot, with mRNA jabs leading to the most significant rise in immunity levels.

Professor Saul Faust, trial lead and director of the NIHR Clinical Research Facility, said the CovBoost study had shown that six different vaccines are safe and effective as booster doses for people who have already had two doses of AstraZeneca or Pfizer/BioNTech.

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The six vaccines tested as a third dose were AstraZeneca, Pfizer/BioNTech, Moderna, Novavax, Janssen (made by Johnson and Johnson) and CureVac (which has ceased production).

"All of the vaccines in our study do show a statistically significant boost... RNA (Pfizer and Moderna) very high, but very effective boosts from Novavax, Janssen and AstraZeneca as well," Prof Faust said.

He added that the vaccines worked well against existing variants, although Omicron was not tested in the study.

Despite this, experts think that T cell immunity - which was studied alongside antibodies in the research - could also play a significant role in fending off the variant.

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T cells play a key role and work alongside antibodies in the immune system to target viruses.

Asked specifically about Omicron, Prof Faust said: "Our hope as scientists is that protection against hospitalisation and death will remain intact."

He said: "Even though we don't properly understand its relation to long-term immunity, the T cell data is showing us that it does seem to be broader against all the variant strains, which gives us hope that a variant strain of the virus might be able to be handled, certainly for hospitalisation and death if not prevention of infection, by the current vaccines.

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He said T cell response was not just focused on the spike protein but "are recognising a much broader range of antigens that might... be common to all of the variants."

Samples from the study have now been passed to the UK Health Security Agency (UKHSA) to look at how well the Omicron variant can be neutralised by vaccines.

Prof Faust continued: "It's really encouraging that a wide range of vaccines, using different technologies, show benefits as a third dose to either AstraZeneca or Pfizer/BioNTech.

"That gives confidence and flexibility in developing booster programmes here in the UK and globally, with other factors like supply chain and logistics also in play."

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The new CovBoost trial, published in The Lancet, involved 2,878 people aged 30 or over receiving a booster 10 to 12 weeks after their initial two-dose vaccination.

Overall, there were 13 different groups testing the boosters or acting as controls, with controls given a meningitis vaccine. Immunity was then assessed after 28 days, with experts saying that more data will be published in the future on the immunity results three months and one year after receiving boosters.

More data will also be published early next year looking at whether a longer period between second and third doses improves the response.

All seven vaccines posed no safety concerns, according to the study, with fatigue, headache and sore arm the most commonly reported issues.