Covid: Three doses of Pfizer vaccine can neutralise Omicron variant, study suggests

A nurse prepares a dose of the Pfizer Covid-19 vaccination Credit: PA Wire/PA Images

Three doses of the Pfizer/BioNTech Covid-19 vaccine were found to neutralise the new Omicron variant in preliminary tests.

The German and US vaccine manufacturers said two doses of their vaccine resulted in significantly lower neutralising antibodies - but a third dose boosted those antibodies by a factor of 25.

The firms said this showed that booster doses could offer good protection against Omicron, which Boris Johnson has said appears to be “more transmissible” than Delta - the current dominant variant in the UK.

The total confirmed cases of the Omicron variant in the UK stands at 568, according to the UK Health Security Agency.

The research found that blood taken from people that had received a third booster shot a month ago neutralised the new variant about as effectively as blood after two doses fought off the original virus - first identified in China.

“Although two doses of the vaccine may still offer protection against severe disease caused by the Omicron strain, it’s clear from these preliminary data that protection is improved with a third dose of our vaccine,” said Albert Bourla, chairman of Pfizer.

“Ensuring as many people as possible are fully vaccinated with the first two-dose series and a booster remains the best course of action to prevent the spread of Covid-19.”

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Although analysis found that two vaccine doses significantly reduce effectiveness against the new variant, the firms said two jabs are still expected to work against severe disease.

“As the vast majority of epitopes targeted by vaccine-induced T cells are not affected by the mutations in Omicron, the companies believe that vaccinated individuals may still be protected against severe forms of the disease, and are closely monitoring real-world effectiveness against Omicron, globally," a statement read.

If required, the firms added that they can deliver a vaccine specifically for Omicron by March 2022.

Margaret Keenan becoming the first patient in the UK to receive the Pfizer/BioNtech vaccine at University Hospital, Coventry. Credit: PA

For the small study on around 20 people, blood samples were obtained from people one month after they received a booster vaccination.

Some samples were from people who had received just two doses three weeks previously.

This latter group had, on average, more than a 25-fold reduction in neutralisation against the Omicron variant compared with the original Wuhan strain.

A World Health Organization official has said that existing vaccines should still protect people who contract the Omicron variant from severe Covid-19 cases.

The WHO's Dr Mike Ryan said there was no indication that Omicron would be better at evading vaccines than other variants.