New Omicron subvariant swamping the U.S. escapes immunity from vaccination and previous infections, new studies say
Scientists have found that the newly dominant omicron subvariants BA.4 and BA.5 evade vaccine- and infection-acquired immunity in the United States.
The subvariants recently caused a new wave of infections in South Africa and are putting the UK on the brink of another outbreak.
BA.5 recently became the dominant subvariant in the US, accounting for nearly a quarter of COVID infections last week, while BA.4 accounted for just over 11% of new cases, CDC data showed.
In a letter to the editor of the New England Journal of Medicine on Wednesday, experts at Harvard Medical School's Beth Israel Deaconess Medical Center (BIDMC) outlined their findings from a recent analysis of antibody protection in 54 individuals against various Omicron subvariants.
Of the participants in their study, 27 had been vaccinated and boosted with the Pfizer-BioNTech vaccine, and 27 had been infected with either the Omicron subvariant BA.1 or BA.2 a median of 29 days prior.
All but one of the participants who had recently contracted the virus had also been vaccinated.
Researchers tested participants' immune responses to subvariants BA.1, BA.2, BA.4, and BA.5, as well as a sample of the original COVID-19 strain (WA1/2020).
Six months after the first two immunization doses, the mean antibody levels against WA1/2020 were 21-fold higher than against the omicron subvariants BA.4 and BA.5.
Two weeks after a booster dose, antibody levels increased significantly but remained three times higher against the BA.1 and BA.2 subvariants than against BA.4 and BA.5.
Spokespersons from Pfizer and BioNTech were not immediately available to discuss the implications of the study results.
The BIDMC study found that the immunity gained by infection with the BA.1 or BA.2 omicron subvariants was also far less effective against BA.4 and BA.5 than against earlier subvariants.
Again, the scientists observed a three-fold reduction in antibody levels against BA.4 and BA.5 compared to the BA.1 subvariant.
Subvariants "essentially escape antibodies"
The researchers said their data showed that subvariants BA.4 and BA.5 "essentially escape neutralizing antibodies induced by both vaccination and infection."
The research team added that the results suggest that "the Omicron variant evolved as neutralization escapes increased," the research team said the study "provides the immunological context for the current surges generated by the BA.4 and BA.4 and BA .5 subvariants in populations with high frequencies caused by vaccination and BA.1 or BA.2 infection.”
Their findings come after a Chinese study published Monday in the journal Lancet Infectious Diseases drew similar conclusions about the ability of BA.4 and BA.5 to evade immunity.
Scientists looked at antibody levels in just over 100 people to study how their immune responses changed when challenged with BA.1, BA.2, BA.2.11, BA.2.12.1, BA.2.13, BA.4, and BA .5 Omicron subvariants were confronted.
They found that in people who received two doses of the Sinopharm COVID vaccine, when it came to targeting omicron subvariants, antibody levels fell drastically compared to neutralizing previous virus strains.
"We found that two [Sinopharm] doses induced detectable neutralizing antibodies against the D614G spike protein mutation in 21 (84%) subjects, but neutralizing activity against omicron subvariants was undetectable or minimal," they said Chinese study researchers.
The D614G mutation was present in the original COVID-19 strain, which was first identified in the Chinese city of Wuhan.
Only between 24% and 53% of people who were boosted with either the Sinopharm or Anhui Zhifei Longcom vaccines showed an immune response to a subvariant of Omicron, according to the Lancet study.
Among 18 participants who had a BA.1 breakthrough infection, the researchers observed a similar level of antibodies against the original virus strain produced in response to all omicron subvariants - except for BA.4 and BA.5, which a Immune system generated response with three times fewer antibodies.
Meanwhile, breakthrough infections caused by BA.2.2 resulted in lower immune responses to all omicron subvariants except the BA.2 mutation.
The U.S. recorded 185,237 new cases of COVID-19 as of Tuesday, according to the CDC.
This story was originally featured on Fortune.com
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