Omicron exceeds other variants in ability to evade protection from previous infection, vaccines: study
By Hannah Jackson
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TORONTO (CTV Network) — The new Omicron variant may have a greater ability than other strains of the virus to escape immune protection from antibodies produced by previous COVID-19 infection, and potentially vaccines.
That’s according to a new, peer-reviewed study published on Saturday in the journal Emerging Microbes & Infection.
The Omicron variant has caused global panic prompting many countries, including Canada, to impose more stringent travel rules.
Experts say the Omicron variant is unusual because it has a high number of mutations in two key areas of the virus’ spike protein.
Dozens of cases of the variant have been detected across Canada.
The researchers said their study showed test tube samples of the Omicron variant “exceeded” all other COVID-19 variants in its ability to evade the protection gained from previous infection or vaccination.
Youchun Wang, senior research fellow from the National Institutes for Food and Drug Control in China, said the research supports recent findings in South Africa that suggest Omicron finds it “easy to evade immunity.”
“We found the large number of mutations of the Omicron variant did cause significant changes of neutralization sensitivity against people who had already had COVID,” Wang said in a press release.
“However, the average ED50 (protection level) against Omicron is still higher than the baseline, which indicated there is still some protection effect can be observed,” Wang continued.
Wang, the vice chairman of the Medical Microbiology and Immunology of the Chinese Medical Association, cautioned that because antibody protection from either vaccination or previous infection decreases over a period of six months, the variant “may be able to escape immunity even better.”
The study suggests that while a third dose of a COVID-19 vaccine “can significantly boost immunity,” the protection it provides from Omicron “may be compromised.”
“In addition, it needs to be re-evaluated whether the therapeutic monoclonal antibodies can still be effective against the Omicron variant,” the study reads.
“More laboratory and the real-world studies are needed to understand whether Omicron can escape from the vaccine elicited immunity to cause more severe disease and death.”
In order to conduct the study, researchers looked at 28 serum samples from patients who were recovering from the original COVID-19 strain, known as SARS-CoV-2.
These were tested against test-tube or in-vitro samples of Omicron and other strains deemed “variants of concern” by the World Health Organization, including Alpha, Beta, Gamma and Delta.
Researchers also tested samples of variants of interest Lambda and Mu.
Wang said the study “verifies the enhanced immune escape” of the Omicron variant, “which sounds the alarm to the world and has important implications for the public health planning and the development of matching strategies.”
However, the team of researchers say more research is needed to better understand the variant, and said real-world studies, not just in-vitro, must be conducted.
The authors said research to determine whether the Omicron variant can “escape from the vaccine elicited immunity to cause more severe disease and death,” must also be conducted.
“It needs to be re-evaluated whether the antibodies can still be effective against the Omicron variant,” the authors wrote in the paper.
“The exact impact to human protection may be influenced by more factors such as the infectivity of Omicron variant relative to other variants to human populations and the viral fitness of Omicron once the humans are infected,” the study reads.
The authors call for “more population studies,” saying research into the level of immune protection and symptoms among people infected with Omicron are needed “to fully establish the global impact of Omicron to the control of [the] COVID-19 pandemic.”
Meanwhile on Saturday, researchers in Israel said they found a three-shot course of the Pfizer/BioNTech COVID-19 vaccine provided significant protection against the Omicron variant.
The study released Saturday, was conducted by the Sheba Medical Center and the Health Ministry’s Central Virology Laboratory.
Researchers compared the blood of 20 people who had received two vaccine doses five to six months earlier to 20 individuals who received a booster a month before.
The study found people who received the second dose five or six months ago did “not have neutralization ability against Omicron.”
“They do have some against the Delta (strain,)” Gili Regev-Yochay, director of the Infectious Diseases Unit at Sheba told reporters.
“The good news is that with the booster dose it increases about a hundredfold,” she said. “There is a significant protection of the booster dose. It is lower than the neutralization ability against the Delta, about four times lower.”
What’s more, on Wednesday, Pfizer released preliminary data that suggests two doses may not be protective enough to prevent an Omicron COVID-19 infection.
However, the company said that a booster dose increased by 25-fold an individual’s level of antibodies against the Omicron variant.
Pfizer’s findings are preliminary though, meaning they have not yet been peer-reviewed.
With files from CTV News’ Nicole Bogart and Reuters
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Sonja Puzicsonja.puzic@bellmedia.ca
