Pfizer, AstraZeneca COVID-19 vaccines less effective against Omicron, study says

Dec. 13 (UPI) -- British researchers announced on Monday that studies show that the COVID-19 vaccines made by Pfizer and AstraZeneca produce substantially fewer antibodies to fight off the Omicron variant than they do against other variants.

The study from Oxford University said blood samples collected from more than two dozen volunteers who'd received both doses of the vaccines were tested against the Omicron variant.

Oxford University, which helped develop the AstraZeneca vaccine, said the study found that both vaccines showed a "substantial decrease in neutralizing" Omicron.

"This will likely lead to increased breakthrough infections in previously infected or double vaccinated individuals, which could drive a further wave of infection, although there is currently no evidence of increased potential to cause severe disease, hospitalization or death," said the report, posted in the journal MedRxiv.

The study said the effectiveness of the vaccines improved with a booster shot.

Teresa Lambe, professor in vaccinology at Oxford, said the study shows the importance of booster shots and called for a continued push to get more people inoculated. File Photo by Robert Ghement/EPA-EFE

"These data will help those developing vaccines, and vaccination strategies, to determine the routes to best protect their populations, and press home the message that those who are offered booster vaccination should take it," Gavin Screaton, head of Oxford University's Medical Sciences Division, said in a statement.

"Whilst there is no evidence for increased risk of severe disease, or death, from the virus amongst vaccinated populations, we must remain cautious, as greater case numbers will still place a considerable burden on healthcare systems."

Teresa Lambe, professor in vaccinology at Oxford, said the study shows the importance of booster shots and called for a continued push to get more people inoculated.

"Vaccination induces many arms of our immune system, including neutralizing antibodies and T-cells," Lambe said in a statement.

"Real-world effectiveness data has shown us that vaccines continue to protect against severe disease with previous variants of concern. The best way to protect us going forward in this pandemic is by getting vaccines in arms."