High levels of coronavirus T-cells that cause the common cold may provide protection against Covid-19, according to a study published by Imperial College London on Monday, which may provide information on approaches to second-generation vaccines, reports Reuters.
Immunity to Covid-19 is a complex process, and although there is evidence of declining antibody levels six months after vaccination, T cells are also thought to play a vital role in providing protection.
The study, which began in September 2020, looked at levels of cross-reactive T cells generated from previous common colds in 52 contacts in households with Covid-19 positive cases shortly after exposure to see if they continued to develop infection.
The 26 who did not develop an infection were found to have significantly higher levels of these T cells than those who became infected. Imperial College does not say how long T-cell protection will last.
"We found that high levels of existing T cells created by the body when infected with other human coronaviruses that cause the common cold can prevent infection with the new coronavirus," said study author Dr Ria Kundu.
The authors of the study, published in Nature Communications, said that the internal proteins of the SARS-CoV-2 virus, which are attacked by T cells, may offer an alternative target for vaccine manufacturers.
Current vaccines against Covid-19 target spike protein, which mutates regularly, creating variants such as Omicron that reduce the effectiveness of vaccines against symptomatic infection.
"In contrast, the internal proteins attacked by the protective T cells we identified mutate much less," said Professor Ajit Lalvani, co-author of the study.
"Therefore, they are very similar between the different variants of SARS-CoV-2, including Omicron. This would mean that new vaccines that include these conserved internal proteins would elicit a broadly protected T-cell immunity that should protect against current and future variants of SARS-CoV-2.
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