The first trials of a vaccine against Covid-19 which relies on a type of immunity different from that targeted by conventional vaccines have shown encouraging results in the stimulation of the immune response, underlines a study published on Tuesday. The first trials (phase 1) in Germany of a vaccine project against the SARS-CoV-2 coronavirus, called CoVac-1, have shown that it induces T-cell immunity, according to this study which is the subject of of an article in the journal Nature. T lymphocytes are a type of white blood cell responsible for the second part of the immune response, cellular immunity, which complements that by antibodies by directly attacking infected cells and not just the virus circulating in the body.
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For the first clinical evaluation of this vaccine, 36 participants aged 18 to 80 received a single dose of the vaccine candidate.
The CoVac-1 aims to induce, in a single injection, a lasting immunity against SARS-CoV2, produced by T lymphocytes, in order to approximate that acquired by a natural infection.
This T cell-induced immunity is an "
important response for virus control, and could be useful for people with immunodeficiency,
" the Nature article points out.
However, “
responses of T lymphocytes specific to SARS-CoV2 were observed in all participants 28 days after vaccination, effects which persisted for at least three months
”.
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These responses exceeded those induced by natural infection with the coronavirus responsible for Covid-19.
In addition, they have not been “
altered
” by any of the variants of current concern (Alpha, Beta, Gamma and Delta).
These results are however very preliminary and only larger trials will be able to confirm the real interest of this vaccine to protect against Covid-19.
A classic vaccine seeks to accustom the body to a virus by making it generate antibodies.
The role of T lymphocytes is still poorly understood in Covid-19, but could allow a broader response.
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In addition, the immunity elicited by T cells is a particularly important issue for people in whom the other part of the immune response, that linked to antibodies, is malfunctioning.
This is the case, for example, in cancer patients, either because of the disease itself or because of the chemotherapy drugs used to fight it, the study explains.
In addition, in addition to attacking infected cells, T cells can also facilitate "
the production of protective antibodies by B cells
", other white blood cells, recalls the article in Nature.
