Vaccine manufacturer Moderna said on Tuesday that the US Food and Drug Administration (FDA) has declined to review its application for the company’s first mRNA-based influenza shot.
The decision comes amid proposed changes to federal vaccine approval procedures under President Donald Trump, which have prompted alarm among public health and medical experts.
Moderna said the FDA’s top vaccine regulator, Vinay Prasad, wrote that the company’s clinical trial was not “adequate and well-controlled” and had not compared the experimental shot against the best available product.
In the trial, Moderna compared its new vaccine with Fluarix, an approved influenza vaccine from GSK.
The company described the refusal as “inconsistent with previous written communications” with the FDA branch that oversees biological products, known as CBER.
“The decision did not identify any safety or efficacy concerns with our product and does not further our shared goal of enhancing America’s leadership in developing innovative medicines,” Moderna CEO Stephane Bancel said.
He added, “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 discussed and agreed with CBER prior to starting.”
Moderna said it had received a refusal-to-file letter, which indicates that the application does not meet the requirements for substantive review. The company has requested a meeting with the FDA to discuss the decision.
The letter did not raise safety or efficacy concerns, and Moderna noted that its mRNA flu vaccine has been accepted for review in the European Union, Canada and Australia.
mRNA technology, used successfully to develop Covid-19 vaccines, has been widely credited with saving millions of lives during the pandemic. Vaccines against Covid-19 are considered safe and effective by global health authorities.
During Trump’s second term, the administration has appointed Robert F Kennedy Jr as health chief. Kennedy, a long-time vaccine sceptic, has reshaped federal health agencies, spreading doubt about the safety of vaccines and altering the paediatric immunisation schedule. Moderna said that Kennedy also terminated federal research grants that had supported mRNA development.
