Another small lab study suggests the omicron variant eludes vaccine protection, even with a booster

(CNN) – A study A detailed description of the virus taken from a single traveler infected with the omicron variant of the coronavirus shows that it can elude the immunity produced by various vaccine combinations.

This is one of the first studies carried out with a few samples in the laboratory, but they all point to the same conclusion: that the omicron variant has mutated in such a way that it reduces the protection of vaccines.

The study, conducted by Dr Sandra Ciesek of the Frankfurt University Hospital and her colleagues, found that even blood samples taken from people who had received booster doses of the Covid-19 vaccine showed reduced activity against the omicron variant.

The researchers took a virus sample from a Zimbabwean traveler who had received two doses of Moderna’s covid-19 vaccine but was infected with the omicron variant.

They used Petri dishes to compare the immune response elicited by this sample with that elicited by a delta variant sample. In all cases, the omicron variant elicited a poorer response, they reported.

“In contrast to the currently circulating delta variant, the neutralization efficacy of the sera elicited by the omicron vaccine was greatly reduced, highlighting that T-cell-mediated immunity is an essential barrier to prevent the severity of the disease. covid-19, “they wrote in their report, posted online as preprint. It has not been reviewed for publication in a medical journal.

The researchers tested this virus sample against blood taken from someone who received two doses of the Pfizer / BioNTech covid-19 vaccine and found an 11-fold reduction in neutralizing antibodies compared to the delta variant in blood taken. after complete vaccination. When virus samples were tested against the blood of someone who received three doses of the Pfizer / BioNTech vaccine, there was still a significant reduction in neutralizing antibodies compared to the delta variant.

The same happened with Moderna’s covid-19 vaccine. They found a more than 20-fold reduction in neutralizing antibodies to omicron compared to delta in people who received two or three doses of Moderna’s vaccine.

According to the report, samples from people who received AstraZeneca’s covid-19 vaccine in one dose and Pfizer’s in another showed no activity against the delta variant or omicron.

They also analyzed the blood of people who had recovered from a natural coronavirus infection, known as convalescent serum. By itself, the serum was not effective against either variant. But if the people had subsequently been infected and vaccinated, their blood provided “superior protection,” the researchers wrote.

It is not clear to what extent these reductions in neutralizing antibody levels are relevant. Doctors have been saying for months that vaccines provide an extra cushion of protection that can overcome the lower immunity caused by the variants. But Ciesek and his colleagues say they believe their findings mean that new vaccine formulations may be necessary.

The body has two lines of defense against infection. Antibodies are proteins that can stop a virus before it infects cells. T cells attack cells that have been infected by invaders such as viruses, and are generally credited with reducing serious infections and the risk of death, but T cell immunity is more difficult to measure in a laboratory.