Early data indicate that there’s no need for a COVID-19 vaccine booster that specifically targets the Omicron virus variant, Dr. Anthony Fauci said Wednesday, the same day the World Health Organization said vaccines may be less effective against the variant.
“Our booster vaccine regimens work against Omicron. At this point, there is no need for a variant-specific booster,” Fauci, the head of the National Institute of Allergy and Infectious Diseases (NIAID), told a virtual press briefing.
Fauci cited an interim analysis from Pfizer and BioNTech, which makes one of the vaccines; a paper from Rockefeller University scientists; a study from his own agency; and a study (pdf) from British researchers.
None of the research has been peer-reviewed. The Pfizer and BioNTech analysis was issued in the form of a press release and the companies have not made the data available for review. NIAID has not released its study yet.
Pfizer said the analysis, which stemmed from a laboratory study on sera from vaccinated persons one month after they got a booster, suggested the booster provided a similar level of neutralizing antibodies to Omicron as the vaccine provided against other variants. Pfizer and BioNTech are working on an Omicron-specific vaccine.
Rockefeller University scientists used plasma samples from vaccinated people to analyze Omicron’s effect and found samples from people who had gotten two doses of the Pfizer or Moderna vaccines were 30- to 180-fold less potent against Omicron than the original strain. Boosters boosted the neutralizing activity 38- to 154-fold.
The NIAID study showed much lower activity after two doses against Omicron but two weeks after a booster, there was a “substantial degree of elevation of the neutralizing titer, well within the range of neutralizing Omicron,” Fauci said.
British researchers, using sequenced positive COVID-19 tests, determined Pfizer’s primary two-dose regimen was much less effective against Omicron, and non-existent for the AstraZeneca-Oxford vaccine. Boosters increased the effectiveness, as measured two weeks after administration, according to the study.
“The message remains clear. If you are unvaccinated get vaccinated, and particularly in the arena of Omicron. If you are fully vaccinated, get your booster shot,” Fauci said.
“Our vaccines work. They continue to provide people protection against this new variant, and booster shots provide the highest level of protection,” added Jeffrey Zients, the coordinator of the White House COVID-19 response team.
Messages sent to the White House and NIAID weren’t immediately returned.
The World Health Organization sounded a different tune in its weekly epidemiological update.
“Preliminary evidence suggests that there may be a reduction in vaccine efficacy and effectiveness against infection and transmission associated with Omicron, as well as an increased risk of reinfection,” the United Nations group said.
“More data are needed to better under the extent to which Omicron may evade vaccine and/or infection derived immunity and the extent to which current vaccines continue to protect against severe disease and death associated with Omicron,” it added.
As a result, the overall risk posed by Omicron is still designated as “very high.”
Other early studies on Omicron, which emerged in Africa by October and was first identified by South African scientists last month, indicate vaccines provide much less protection against both infection and hospitalization.
Fauci did acknowledge one of the studies, which pegged protection against infection as dropping from 80 percent to 33 percent and protection against hospitalization as dropping from 93 percent to 70 percent.
“Obviously, this is significantly down, but there is the maintaining of a degree of protection against hospitalization,” Fauci said.
While experts around the world have cautioned against reading too much into emerging data, the early studies point to the vaccines having little effect against infection from Omicron, a variant of the CCP (Chinese Communist Party) virus. The CCP virus causes COVID-19.
Boosters do restore some of the lost protection, the data indicate. But some research shows the level of protection is down from that provided against Delta.
A pre-print, unpublished study from Sheba University in Israel, for instance, suggested three shots of Pfizer—the two-shot primary regimen and a booster—provided four times lower protection than against earlier strains.
Small studies have also suggested Omicron can evade natural immunity, or the protection from prior infection, better than the Delta variant.
Most of the research deals with Pfizer’s vaccine, which is widely available in the United States, the United Kingdom, and South Africa, among other countries.
Previous research, primarily before Omicron emerged, showed the highest level of protection came from natural immunity, though experts warn against remaining unvaccinated because a small portion of people who get infected, primarily those who haven’t gotten a vaccine, die with COVID-19.
Natural immunity, estimated at 72 percent in Gauteng province in a recent seropositivity survey, may explain why many Omicron-caused cases in South Africa have been mild so far, Shabir Madhi, a professor of vaccinology at the University of the Witwatersrand, said on a recent podcast.
“We know natural infection induces probably a much more broad repertoire of T cell response, compared to what is induced with spike protein-based vaccines. And I think that is important to keep in the back of our mind when we see what’s unfolding currently in South Africa, and what to expect in other settings, which might have a very different epidemiology up until now.”