Reacción a "A phase 3 clinical trial has tested a new RNA vaccine against influenza"

The article presents a high-quality scientific study, published in one of the most prestigious biomedical journals, The New England Journal of Medicine, renowned for disseminating clinical studies of high therapeutic relevance. In this case, the efficacy of a quadrivalent messenger RNA (mRNA) vaccine, developed by Pfizer, is evaluated in a phase 3 clinical trial in humans. The formulation includes four mRNA sequences that encode the hemagglutinins of the H1N1 and H3N2 influenza A viruses, as well as the Yamagata and Victoria lineages of influenza B.

The efficacy of this vaccine is compared to that of the currently used conventional vaccine, which contains purified hemagglutinins from the same four viruses. The study analyzes the vaccine's ability to prevent infection, induce specific antibodies against seasonal influenza viruses, and stimulate T-cell-mediated cellular immunity, in addition to quantifying adverse effects of the vaccination.

The results are promising, although limited to a population aged 18 to 64, a group with a lower risk of severe influenza complications compared to older adults, especially those over 75. The study is part of the technological competition between companies like Moderna and Pfizer to develop more effective flu vaccines.

The mRNA-based formulation shows greater reactogenicity, meaning a higher frequency of mild or moderate symptoms after vaccination, compared to the conventional vaccine. No conclusive data are provided on its ability to prevent severe acute respiratory illness or on its long-term efficacy (more than one year), although the advance in protection against influenza A is acknowledged, while limitations in coverage against influenza B and in tolerability are noted.

The proposed vaccine offers a significant improvement in the immune response, both humoral (antibodies) and cellular (T lymphocytes), compared to the inactivated vaccines currently used in seasonal campaigns. Although protection against infection still has room for improvement, the mRNA platform allows for greater flexibility and speed in vaccine design and production, as well as the introduction and modification of antigens. This represents a strategic advantage over conventional formulations, which require more complex and lengthy processes.

[Regarding potential limitations] The higher reactogenicity observed could affect public acceptance, especially in the context of annual vaccinations. Furthermore, the study does not provide data on efficacy in preventing severe disease or on its performance in at-risk groups such as young children and the elderly. The lack of this data limits the extrapolation of results to vulnerable populations. An improvement in efficacy would also be expected, but this needs to be proven.

If reactogenicity can be reduced without compromising efficacy, this vaccine could become a viable alternative to current formulations. Additionally, the inclusion of mRNA encoding other viral proteins, such as neuraminidase, could broaden immunological coverage and improve the protective profile of future versions.