Moderna Delays Flu/COVID Combo Shot Filing

Regulatory Withdrawal Follows FDA Consultation

Moderna has voluntarily withdrawn its application for FDA approval of its combination flu/COVID-19 vaccine, known as mRNA-1083, after recent discussions with the agency. The move comes just two weeks after the biotech company announced that the combination shot generated a stronger immune response than currently approved vaccines for both influenza and COVID-19.

According to Moderna, the vaccine “outperformed current shots for both diseases” in Phase III trial results shared earlier this month. However, following its consultation with the FDA, the company opted to pull its biological license application (BLA), which had originally been submitted in late 2024. Moderna had aimed for approval by late 2025.

The decision appears to align with the FDA’s request for more comprehensive efficacy data specific to the flu component of the vaccine. As stated during Moderna’s Q1 earnings call, the company had already anticipated a delay, projecting approval might not be achieved until 2026.

Clinical Data and Market Response

The combo vaccine mRNA-1083 incorporates elements of Moderna’s standalone flu vaccine candidate mRNA-1010 and its next-generation COVID-19 vaccine, mRNA-1283. Moderna’s president, Dr. Stephen Hoge, addressed the issue during the Q1 earnings call, stating, “it makes good scientific sense that that would be a part of the review that's going on for our flu-COVID combination.”

The company expects to resubmit the BLA later this year once Phase III efficacy data from the ongoing trial of mRNA-1010 becomes available. Interim results are anticipated by summer. Dr. Hoge added, “we’ll just go forward with whatever feels like the most pragmatic approach and, ultimately, the one that the FDA guides us to do.”

Despite reassurance that the FDA interactions remain “business as usual,” the withdrawal impacted investor sentiment. Moderna shares fell 4.5% in early trading Wednesday, dropping from $27.99 to $26.79 per share.

Vaccine Regulation Climate Shifts

The delay comes amid broader regulatory changes. The FDA has recently adjusted its approval strategy for new COVID-19 vaccines, including a missed deadline for a Novavax protein-based candidate, which was eventually approved only for older adults and high-risk individuals. In a recent editorial by FDA Commissioner Marty Makary and CBER Director Vinay Prasad, new risk-based evaluation standards were outlined.

Additionally, the U.S. Department of Health and Human Services (HHS) now requires that all future vaccine trials include a full placebo control arm. Industry observers, including analysts at Leerink Partners, criticized this move, calling it “questionable and risky” and suggesting that “placebo-controlled trials are unnecessary and unethical for many populations.”

Competitive Landscape

Moderna’s chief rival, Pfizer, is also actively developing COVID-19 and combination vaccines. Pfizer has submitted applications for pediatric COVID-19 mRNA vaccines and is conducting Phase III trials for a flu/COVID-19 combo shot targeting children aged six months to 11 years.

While Moderna has deprioritized mRNA-1083 due to regulatory delays, the company remains committed to revisiting the application with updated data. Its focus in the near term is squarely on completing the evaluation of mRNA-1010, which could play a pivotal role in its resubmission strategy.

Highlights

• Moderna withdrew its FDA application for the flu/COVID-19 combo vaccine mRNA-1083 following agency discussions.
• Phase III results showed the shot generated strong antibody responses compared to existing flu and COVID-19 vaccines.
• The company now expects to resubmit the BLA later in 2025 after releasing interim data from its mRNA-1010 flu vaccine trial.
• Moderna shares dropped 4.5% following the news.
• Regulatory changes, including new placebo requirements, are complicating vaccine approvals in the U.S.
• Pfizer remains a strong competitor, advancing its own combination vaccine programs.