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

The new mRNA influenza vaccine evaluated in this phase 3 trial represents a significant advance over traditional platforms. In a season dominated by subtype A, the vaccine showed a 34.5% improvement in relative efficacy compared to a standard inactivated vaccine and generated higher antibody titers for H1N1 and H3N2, as well as a significantly more robust T-cell response, which could translate into broader and potentially longer-lasting protection.

However, the absence of circulating influenza B virus during the study and the fact that immunological non-inferiority against B lineages was not met raise some questions about its performance in seasons with different viral compositions.

The immunological cost of this improved performance is greater reactogenicity, as previously observed with the mRNA platform. The frequency of local and systemic reactions was higher, with fever occurring in 5.6% of those vaccinated with mRNA compared to 1.7% with the conventional vaccine, although most were mild and transient. This can have a considerable impact on public acceptance and tolerability.

Looking ahead, mRNA technology opens a promising path toward more agile and potentially more universal influenza vaccines. Its ability to induce potent cellular responses and to be rapidly updated against new lineages could change the paradigm of seasonal influenza campaigns. However, it is still necessary to demonstrate its year-to-year consistency, its actual efficacy against subtype B viruses, and its performance in higher-risk populations not included in the trial (the elderly, pregnant women, and immunocompromised individuals).

This is an important, but still preliminary, step toward a new generation of more flexible influenza vaccines with more ambitious effectiveness.