The Pfizer’s vaccine is being reported to be partially effective against the latest Covid-19 variant, which is the Omicron variant, Bloomberg News reported on Tuesday, citing the research head of a laboratory at Africa Health Research Institute in South Africa.
Its evasion is not complete and a booster shot could provide additional protection, according to the report, citing Alex Sigal, head of the lab.
The Omicron variant, first detected in southern Africa last month, has triggered alarms globally of another surge in infections, with more than two dozen countries from Japan to the United States reporting cases.
It’s the first experiment to directly look at how the Omicron virus might behave in vaccinated people.
The tests in lab dishes using samples from 12 people who had been fully vaccinated with Pfizer’s vaccine showed the Omicron variant could evade the immune protection built by the vaccine but not completely.
“There is a very large drop in the neutralization of Omicron by BNT162b2 [Pfizer/BioNTech] immunity relative to an ancestral virus,” Sigal said on Twitter.
“Omicron escape from BNT162b2 neutralization is incomplete. Previous infection + vaccination still neutralize,” he added.
“I thought this news was very positive. I expected worse,” Sigal said in a telephone interview. The mutations that characterize the Omicron variant, he said, looked like they could allow it to evade the immunity offered by vaccines to a greater extent.
But the experiment indicates it doesn’t. “This is not a variant that has completely escaped,” he said. “It certainly escapes. It is certainly bad. But it looks to me like there are ways of dealing with it.”
Sigal’s team used human lung cells for the tests. Blood from the six volunteers who had been infected and then vaccinated was better able to neutralize the virus, they reported in a study submitted to an online preprint site. It has not been peer-reviewed.
“Previous infection, followed by vaccination or booster, is likely to increase the neutralization level and likely confer protection from severe disease in Omicron infection,” Sigal’s team concluded.
The study does not reflect actual infection with the virus.
It found a 41-fold decrease in the levels of neutralizing antibodies against Omicron in some of the samples, compared to those generated against one of the earlier strains of the virus — although it’s not clear how that might translate into a reduction in real-life protection.
The World Health Organization on Nov. 26 classified it as a “variant of concern,” but said there was no evidence to support the need for new vaccines specifically designed to tackle the Omicron variant with its many mutations.