FDA refuses to review Moderna's influenza vaccine application

The United States Food and Drug Administration (FDA) will not review Moderna's approval application for its influenza vaccine, the company said on Tuesday (Feb 10), sending its shares down 8 per cent in extended trading.

In its refusal-to-file letter, the FDA said Moderna's choice to compare mRNA-1010 to an already licensed standard-dose seasonal influenza was the sole reason for the refusal to initiate a review of the application.

The letter specifically cited the lack of an "adequate and well-controlled" study with a comparator arm that "does not reflect the best-available standard of care", Moderna said.

"This decision by CBER (Center for Biologics Evaluation and Research), which did not identify any safety or efficacy concerns with our product, does not further our shared goal of enhancing America's leadership in developing innovative medicines," said CEO Stephane Bancel.

The letter is inconsistent with previous written communications from the health regulator, the company said.

"It should not be controversial to conduct a comprehensive review of a flu vaccine submission that uses an FDA-approved vaccine as a comparator in a study that was discussed and agreed on with CBER prior to starting," Bancel said.

The company's marketing application for mRNA-1010 included two late-stage studies, which met the main-goals of the trials.

Moderna said last year the mRNA-1010 vaccine was 26.6 per cent more effective than an approved annual flu shot from GSK.

The vaccine maker said it has requested a meeting with the regulator to understand the path forward.

The development comes little over a month after the US overhauled its longstanding guidance on childhood immunisation and rolled back recommendations for routine vaccination against six infectious diseases, including influenza.

In an interview with Bloomberg TV earlier this year, the company said it does not plan to invest in new late-stage vaccine trials because of growing opposition to immunisations from US officials.

Moderna last year withdrew its application seeking approval for its flu and COVID combination vaccine to wait for efficacy data from a late-stage trial of its influenza vaccine.

The vaccine is currently under review in the EU, Canada and Australia, with the company expecting potential approvals to come in late 2026 or early 2027.

Current FDA-approved influenza vaccines include those made by AstraZeneca and Sanofi.