(CNN) – Immunity against the omicron variant of the coronavirus declines with the Moderna and Pfizer / BioNTech vaccines, but not as much as after a natural infection, researchers reported Friday.
The researchers say their findings show the need for vaccines that specifically protect against the omicron variant.
Dr. Emilia Sordillo, from the Icahn School of Medicine at Mount Sinai in New York, and her colleagues analyzed the blood of people who had been vaccinated, or vaccinated and boosted by Moderna or Pfizer / BioNTech, as well as blood from people who had recovered from covid-19.
A Pfizer COVID-19 vaccine is prepared for administration at a vaccination clinic on September 22, in Los Angeles. Credit: Frederic J. Brown / AFP / Getty Images
Although the tests were conducted on laboratory plates, the researchers claimed that the experiment reproduced real-life conditions because they used live viruses. They looked for what are known as neutralizing antibodies – immune system structures that can attach to the virus and prevent it from infecting cells. “In all 85 samples, the reduction in omicron neutralization was greater than 14.5 times,” compared to the beta variant and the original strain, they wrote. “In comparison, there was only a four-fold reduction against beta in the same sample.”
“In fact, 16.5% of the samples lost all neutralizing activity against omicron.” That included nearly three-quarters of blood samples from people who had recovered from infections.
“Our findings support recent reports describing significantly reduced protection against reinfection and almost non-existent vaccine efficacy against symptomatic disease after two doses of BNT162b2 (Pfizer),” they wrote. However, people who received boosters from Pfizer had protection “on the order of 75%,” they wrote.
Increase in omicron infections “is unlike anything we have seen,” says an expert
The researchers found no evidence that Moderna’s COVID-19 vaccine offers stronger protection than Pfizer’s. The blood of people who received two doses of the Pfizer / BioNTech vaccine produced neutralizing levels of antibodies that were 23 times lower against omicron than against the original strain of the virus, and the antibody levels of people who received the vaccine from Modern were 42 times smaller. For people who received booster doses, the neutralization activity was 7.5 times lower for the Pfizer / BioNTech vaccine and 16.7 times lower for the Moderna vaccine.
In general, antibody protection correlates with real-life protection, but does not measure the long-term protection against severe illness and death provided by a slower-growing and more durable type of protection: immune cells. called T cells.
“We must remember that the relationship between measurable neutralizing antibodies and the clinical course of the infection is not straightforward. In general, antibodies are necessary to prevent the initial infection; but cellular immunity – which can be maintained – is necessary to prevent severe disease, ”Dr Peter English, a UK communicable disease control expert, said in a statement.
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“Importantly, the study supports the view that a third dose of the vaccine significantly improves the antibody response against omicron infection,” added English, who was not involved in the study.
Dr Julian Tang of the University of Leicester, who was also not involved in the study, also said that T-cell responses are important for long-term protection against severe disease.
“The bottom line is that boosting existing immunity (either by vaccine or naturally acquired) helps protect against infection / reinfection to some extent, as well as boosting existing T-cell responses, all of which which will help protect us against omicron. So it’s important to get these booster doses, especially if you’re in one of the most vulnerable groups, ”Tang said.
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