AstraZeneca has said that a third dose of its COVID-19 vaccine “significantly” lifted antibody levels against the Omicron coronavirus variant, citing data from a new laboratory study.
Findings from the study, yet to be published in a peer-reviewed medical journal, match those from rivals Pfizer-BioNTech and Moderna, which have also found a third dose of their shots works against Omicron.
The study on AstraZeneca’s vaccine, Vaxzevria, showed that after a three-dose course of the vaccine, neutralising levels against Omicron were broadly similar to those against the virus’s Delta variant after two doses.
Levels of neutralising antibodies were also higher with the booster jab than with individuals who had previously been infected and recovered naturally.
The company said the researchers at Oxford University who carried out the study were independent from those who worked to develop the vaccine with AstraZeneca last year.
“As we better understand Omicron, we believe we will find that T-cell response provides durable protection against severe disease and hospitalisations,” Mene Pangalos, the head of AstraZeneca’s biopharmaceuticals R&D said, referring to a critical component of the immune system that responds to fight infection.
The threat of the highly transmissible Omicron variant looms large over the December holiday season, forcing many governments to roll out new curbs and urge citizens to get vaccinated.
However, separate UK research has suggested that Omicron infections are less likely to result in hospitalisation compared with the Delta variant.
Boosters ‘limit Omicron spread’
Oxford’s researchers analysed blood samples taken from individuals infected with COVID-19; those vaccinated with two doses plus a booster; and those who had reported a previous infection.
“It is very encouraging to see that current vaccines have the potential to protect against Omicron following a third dose booster,” said University of Oxford Professor John Bell, one of the study investigators.
“These results support the use of third dose boosters as part of national vaccine strategies, especially to limit the spread of variants of concern, including Omicron.”
On Wednesday, the World Health Organization issued a stark warning to rich countries over boosters, arguing that they divert valuable jabs away from poorer nations – and encourage the virus crisis to worsen.
“Blanket booster programmes are likely to prolong the COVID-19 pandemic, rather than ending it, by diverting supply to countries that already have high levels of vaccination coverage, giving the virus more opportunity to spread and mutate,” WHO Director-General Tedros Adhanom Ghebreyesus warned.
The latest data suggest Omicron does not cause more severe illness than previous variants, including Delta, but as soaring infection numbers threaten to overwhelm health systems, scientists warn it could cause more deaths.
AstraZeneca said on Tuesday it was working with its partner Oxford to produce a vaccine tailored for Omicron, joining similar efforts from other vaccine makers.
Scientists and governments are scrambling to bolster defences against Omicron with shots and therapies, as the variant threatens to become dominant globally and has prompted renewed curbs ahead of the holidays to contain infections.
Britain earlier this month backed the use of boosters after it found that a third dose significantly restored protection against mild disease caused by Omicron, in part reversing an otherwise steep drop in vaccine effectiveness.