Scientists have found that the new US-dominant Omicron sub-variants, BA.4 and BA.5, are evading the vaccine and acquired immunity from infection.
Subvariants have recently caused a new wave of infections in South Africa and are pushing the UK to the brink of another wave of disease.
BA.5 recently became the dominant sub-variant in the United States, 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 director of the New England Journal of Medicine On Wednesday, experts from Harvard Medical School’s Beth Israel Deaconess Medical Center (BIDMC) outlined the results of a recent analysis of the antibody protection of 54 individuals against various Omicron sub-variants.
Of the participants in their study, 27 had been vaccinated and boosted with the Pfizer-BioNTech vaccine and 27 had been infected with the BA.1 or BA.2 Omicron sub-variant a median 29 days earlier.
All but one of the participants who had recently been infected with the virus were also vaccinated.
The researchers tested the participants’ immune responses to the BA.1, BA.2, BA.4 and BA.5 subvariants, as well as a sample of the original COVID-19 strain (WA1 / 2020).
Six months after the first two immunization doses, median antibody levels against WA1 / 2020 were 21 times higher than those against Omicron BA.4 and BA.5 subvariants.
Two weeks after a booster injection, antibody levels increased substantially, but remained three times higher against the BA.1 and BA.2 subvariants compared to BA.4 and BA.5.
Spokesmen for Pfizer and BioNTech were not immediately available to discuss the implications of the study findings.
The BIDMC study found that immunity acquired through infection with the Omicron BA.1 or BA.2 subvariants was also much less effective against BA.4 and BA.5 than the previous subvariants.
Again, the scientists observed a threefold reduction in antibody levels against BA.4 and BA.5 compared to the BA.1 sub-variant.
Subvariants “substantially escape antibodies”
The researchers said their data showed that the BA.4 and BA.5 subvariants “substantially escape neutralizing antibodies induced by both vaccination and infection.”
Adding that the results suggested that “the Omicron variant continued to evolve with an increasing neutralization leak,” the research team said the study provided “an immunological context for the current spikes caused by the BA.4 and BA subvariants. .5 in populations with high frequency of vaccination and BA.1 or BA.2 infection.
Their findings come after a Chinese study published in Infectious diseases of the lancets Monday’s newspaper drew similar conclusions about BA.4 and BA.5’s ability to evade immunity.
Scientists studied antibody levels in just over 100 people to examine how their immune responses varied with respect to BA.1, BA.2, BA.2.11, BA.2.12.1, BA.2.13, BA.4 and BA.5 Subvariants of Omicron.
They found that in people who had received two doses of the Sinopharm COVID vaccine, antibody levels dropped dramatically when it came to fighting Omicron’s sub-variants compared to neutralizing previous strains of the virus.
“We found those two [Sinopharm] the doses induced detectable neutralizing antibodies against the D614G spike protein mutation in 21 (84% of) individuals, but the neutralizing activity against omicron subvariants was either not detectable or was only minimally detectable, “the Chinese study researchers said. .
The D614G mutation was present in the original COVID-19 strain first identified in the Chinese city of Wuhan.
Only between 24% and 53% of people who had been boosted with the Sinopharm or Anhui Zhifei Longcom vaccine had an immune response to any sub-variant of Omicron, the Hand the study said.
Among the 18 participants who had had a breakthrough BA.1 infection, the researchers observed a similar level of antibodies against the original virus strain that was produced in response to all sub-variants of Omicron, except BA.4 and BA. .5, which generated an immune response with three times fewer antibodies.
Meanwhile, the breakthrough infections caused by BA.2.2 have resulted in lower immune responses to all sub-variants of Omicron, apart from the BA.2 mutation.
On Tuesday, the United States recorded 185,237 new cases of COVID-19, according to data from the CDC.
This story was originally posted on Fortune.com