Will covid-19 booster shots be the new norm?

A study recently published in the scientific journal ‘Nature’, conducted by a large team of researchers from Great Britain and Singapore, indicated that immunity to Covid-19 may not just be a matter of antibodies available to fight the virus.

For several months, scientists monitored healthcare professionals who had potentially been exposed to the virus but were not known to become ill with Covid-19 and never tested positive. Antibody serological tests also did not show remarkable results. However, it drew the attention of experts that the 58 HIV-negative health workers had more multispecific memory T cells than a comparative group whose potential exposure to the virus was much lower.

The T cells were targeted in particular against the transcription-replication complex (TRC), the same complex that effectively spreads the virus in the body. The study revealed that the group’s T cells had a greater amount of IFI27, a protein that is “a robust innate signature of SARS-CoV-2, which allowed the conclusion that it was a suggestion of an “abortive infection”.

In other words, the T cells, the study points out, possibly interrupted the infection at the beginning. However, the big question is where the 58 healthcare professionals in question got this unusually high T-cell immunity.

One possible conclusion could be that repeated exposure to various coronavirus variants such as SARS-CoV-2 – if it becomes endemic and people come into frequent contact with a small number of pathogens – may make the immune system more able to deal, with antibodies or T cells, which would mean a step closer to collective immunity.

The conclusion seems to indicate that future Covid-19 vaccines will have to be tuned to effectively protect against new coronavirus variants, in the same way that flu vaccines are tuned. Vaccines are currently being developed to protect against Delta variant mutations.

For now, booster shots of Covid-19 are needed because the number of antibodies in the blood decreases over time. With mRNA vaccines, the effectiveness appears to start to wane after six months of people receiving a second dose. In other words, booster vaccines will be a ‘necessary evil’ until the development of new vaccines that offer more transversal protection to Covid-19.