As time passes and the Omicron variant continues to spread, more information is becoming available on the latest version of the virus and how it differs from its predecessors. Studies are now shedding more light on initial concerns about it being more transmissible and whether or not it is more likely to cause severe illness in some people. But new research has also found that some currently available vaccines aren’t able to protect against infection with Omicron as well as they had against previous variants.
A study conducted by Humabs Biomed SA and the University of Washington that has not yet been peer-reviewed compared the effectiveness of vaccines against Omicron versus how well they could protect against the original strain of the virus. Results showed that shots from Johnson&Johnson, the Sputnik V vaccine developed in Russia, and the Sinopharm vaccine developed in China had no neutralizing activity against the variant, Reuters reports. Researchers also concluded that vaccines produced by Pfizer-BioNTech, Moderna, and AstraZeneca were all still active against Omicron—especially in patients who had been previously infected by the virus and received the shots—but saw a significant drop in effectiveness compared to previous versions of the virus.
The results come days after another study from the University of Hong Kong found that none of the blood samples taken from 25 patients who had received Sinovac—another wide administered vaccine from China—produced sufficient antibodies to prevent infection from Omicron, The New York Times reports. Researchers still expected that those who received the vaccine are likely at lower risk of severe illness or death from the virus. But since Sinopharm and Sinovac collectively make up nearly half of all shots that have been administered to the global population, experts are expressing concern that the decreased protection means new waves of infections could follow—especially in the developing world where a majority of the shots were distributed.
Experts explain that the results only show a partial picture of how vaccines will work against Omicron because of how the immune system works. Besides antibodies, which are crucial in providing the first line of defense against viruses, vaccines also cause the body to produce T cells. Fortunately, studies have shown these are still faring well in the case of the latest variant.
“What you lose first is protection against asymptomatic mild infection, what you retain much better is protection against severe disease and death,” John Moore, PhD, a virologist at Weill Cornell Medicine in New York, explained to The Times. He added that initial research that found Omicron was less likely to be fatal than the Delta variant was “a silver lining.”
But while those who have already received the vaccines may still be less likely to become seriously sick or die from the virus, experts fear that the increased risk of infection could allow the variant to spread to the unvaccinated who aren’t protected from severe disease—and even potentially create more variants. “The sheer scale of infection will overwhelm health systems, simply because the denominator will be potentially so big,” J. Stephen Morrison, PhD, director of the Global Health Policy Center at the Center for International and Strategic Studies, told The Times.
Recent research has also provided tentative answers on how booster shots might help better protect against the virus. One study from the U.K. Health Security Agency that found a booster of the Pfizer vaccine restored protection against symptomatic breakthrough infections to 75 percent against the latest version of the virus. And in a study released on Dec. 20, Moderna said that lab tests found a 50-microgram booster dose of its vaccine increased antibody levels by about 37-fold, The Times reports.
Other research released from Pfizer-BioNTech also showed promise that a third shot could help prevent infection. “Our preliminary, first data set indicate that a third dose could still offer a sufficient level of protection from disease of any severity caused by the Omicron variant,” Ugur Sahin, MD, the chief executive officer of BioNTech, said in a statement.
Unfortunately, experts are now concerned that the lack of access to the apparently more effective Moderna and Pfizer mRNA-style vaccines could create serious complications in the fight against COVID-19. “We may be seeing a situation where countries say, ‘If developed countries don’t want these vaccines, then we don’t want these vaccines,'” Seth Berkley, MD, CEO of global vaccine alliance Gavi, told The Times. “That, of course, would be the wrong interpretation, if it turns out that these vaccines prevent against severe disease and death.”