This is good news, as it demonstrates the therapeutic efficacy of a new drug against the highly pathogenic H5N1 avian influenza virus that seriously affects wild birds and poultry, as well as dairy cows in the United States and which, to date, has infected dozens of people in this country, resulting in one death.

This virus is considered a potential candidate to cause a future pandemic. Therefore, it is essential to develop all possible tools to control it, especially effective vaccines and drugs.

Baloxavir is an antiviral approved by the United States in 2018 that has already demonstrated its therapeutic value against the current viruses that cause human influenza type A (H1N1, H3N2). This study investigates its usefulness against the aforementioned H5N1. Why is it important? Because its mechanism of action is different from that of another common anti-flu drug, oseltamivir. Baloxavir acts on one of the virus‘ polymerases, while the other acts on another essential virus enzyme, neuraminidase. Having two different viral targets is very important in the treatment of influenza, due to the virus’ high capacity to generate drug-resistant variants.

The study was carried out on mice, which is one of the few animal models available in flu research, but it lays the foundations for validating its use in serious cases of H5N1 infection or for considering it as a useful drug in the event of a pandemic caused by this virus. On the other hand, this study also shows that baloxavir is effective when the infection is produced via the respiratory and ocular tracts (inhalation of aerosols or through contact with mucous) but not when the infection is oral, which gives rise to speculation about the pathogenicity mechanisms of the virus, which will be investigated in future studies.

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