T cells in patients with Pfizer Covid vaccination remain robust against serious diseases | Coronavirus – World

South African researchers studying how the body’s immune system responds to the Omicron variant found that T cells in people who received the Pfizer vaccine remained robust, despite Omicron’s ability to evade other defense mechanisms, to potentially protect against serious diseases.

Research raises hope that similar reactions may occur with other vaccines and in unvaccinated people infected with the coronavirus.

T cells are a type of white blood cell that determines our body’s immune response to antigens – foreign substances – in the body.

While neutralizing antibodies produced by vaccines are designed to prevent infection that Omicron appears to be able to bypass, T cells recognize the virus once it has infected cells and then move to kill them.

The data are the result of some of the earliest laboratory tests to investigate how effective the T cell response is against Omicron, and suggest that the T cells in samples from people double-vaccinated with the Pfizer vaccine may have the T cells -Answer stayed 70% to 80% effective.

Wendy Burgers from the University of Cape Town, who worked with Alessandro Sette and his team at the La Jolla Institute for Immunology in California, presented their team’s results at a world Health Organizational symposium earlier this week.

Speaking to the Guardian, she said the results confirmed her expectation that the body’s wider repertoire of immune responses to Omicron could help prevent more serious diseases.

“Our research looked at T cells,” said Burgers. “Antibodies are always a good starting point for testing whether a vaccine is working, because what the antibodies prevent is that the pathogen does not get into the cell in the first place.

“When it breaks the defenses and cells become infected, T cells come in and clear infected cells so they stop replicating and become virus factories. You nip it in the bud. “

The problem with the T cell response to Omicron has been a missing piece of the puzzle since the variant first appeared, as it was shown not only to be more contagious, but also to be able to avoid antibody responses acquired by vaccination.

“So far we’ve looked at samples from people who received two doses of the Pfizer vaccine,” said Burgers. “In contrast to antibodies in sera, we look at the cells themselves, which is why assays and data come out slower because they are more specialized and demanding.”

According to Burgers, the neutralizing antibodies that recognize the spike protein of the virus and stick to it to prevent infection seem to be bypassed by Omicron’s 32 mutations in the spike protein, while T cells hold the virus in a much larger part of the protein and seem to be less inhibited by Omicron’s mutations.

“From what we know about the work of T cells, we thought there might be a small loss in fighting infection by T cells, and we see that experimentally in the early data, with 70-80% effectiveness is maintained.

“We’ll have more data from other vaccines next week, mostly from J&J [Johnson & Johnson] Vaccine, and we also look at unvaccinated people who have had a previous infection, although we expect it to be fairly consistent. “

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Burgers, however, is cautious about using evidence of persistent T-cell effectiveness as an explanation for why so far South Africa Anecdotally, there seems to have been less severe illnesses with Omicron than with other variants. “It’s hard to tell, and we will have different experiences with Omicron in different populations in different parts of the world.

“But what we know about T cells in general, and in particular about Covid-19, is that T cells may not prevent infection, but they offer some protection against serious diseases. In this respect, the data are reassuring when what we see is correct. “

The same message was repeated in Nature on Friday. the one about Sette’s work in La Jolla. reported, warns that while there is no way to draw a direct line between levels of T-cell reactivity and protection from serious illness, previous studies have shown that T-cell responses to Sars-CoV-2 correlate with lower viral load and less severe illness ”.


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