Samples from people who had two doses of the Covid-19 vaccine saw, on average, a more than 25-fold reduction in neutralization ability against the Omicron variant than the earlier virus, « indicating that two doses of BNT162b2 may not be sufficient to protect against infection with the Omicron variant, » the companies said.
The companies said two doses may still provide protection against severe disease.
« 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, » Pfizer Chairman and CEO Albert Bourla said in a statement. « 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. »
The initial lab studies used serum from blood from individuals who received two or three doses of the Pfizer/BioNTech Covid-19 vaccine. The sera was collected from subjects three weeks after their second dose, or one month after a third dose.
Pfizer and BioNTech are continuing to develop a variant-specific vaccine for Omicron and say it will be available by March, if it’s needed.
The data released Wednesday has not been peer-reviewed or published.
« My impression is if you get a booster you are protected, especially against severe disease, » Sigal said.
Since reports of the Omicron variant emerged in late November, US health officials have urged people to get vaccinated and boosted. Last week, the US Centers for Disease Control and Prevention began recommending all adults get a Covid-19 vaccine booster.
Adults who have had the Pfizer or Moderna Covid-19 vaccines are eligible to get a booster six months after their second shot. Those who got the Johnson & Johnson one-shot vaccine are eligible for a booster of any authorized vaccine two months after their first dose.