Race to develop mRNA flu vaccines will contend with a longer review than Covid-19

The success of messenger ribonucleic acid (mRNA) Covid-19 vaccines may have sped up the timelines for seasonal influenza shots based on having the same platform, but non-emergent conditions may mean a relatively standard, and therefore slower, approval pathway. The fast-tracked timeline for Covid-19 vaccines has set the stage for quicker development of mRNA vaccines for influenza. However, unlike Covid-19 vaccines, there are approved—albeit unsatisfactorily effective—alternatives for the prevention of influenza. In the absence of a sense of urgency for influenza vaccines in the middle of a pandemic, the upcoming investigational mRNA vaccines will likely follow the same regulatory route as traditional vaccine approvals. Unlike Covid-19 vaccines, which were authorised based on placebo-controlled studies, influenza vaccines may need efficacy and safety comparisons to available alternatives to guide recommendations. The risk-benefit analysis for seasonal influenza vaccines is different from that of Covid-19 mRNA vaccines being authorised in the middle of a pandemic. For example,...