Moderna’s Combined Flu and Covid Vaccine Shows Promise Amid Regulatory Challenges

Moderna has developed an mRNA-based combination vaccine, mRNA-1083, targeting both influenza and covid-19. Recent Phase III clinical trial data published in JAMA reveal that this vaccine elicits immune responses that are at least as strong, and in some cases stronger, than those generated by separate flu and covid vaccines. The trial involved approximately 8,000 participants aged 50 and older, demonstrating consistent efficacy across age groups.

Participants receiving mRNA-1083 showed particularly enhanced antibody responses to circulating flu strains compared to those receiving separate vaccines. Additionally, the vaccine was well-tolerated with a safety profile comparable to existing vaccines. These findings suggest that a single combined shot could simplify immunization schedules and improve vaccination rates by reducing the number of injections needed.

However, the vaccine’s path to approval faces significant hurdles due to recent changes in FDA vaccine approval policies. The Department of Health and Human Services, led by Health Secretary Robert F. Kennedy Jr., has mandated that all new vaccines must undergo placebo-controlled trials, even when effective vaccines already exist. This policy shift could delay or prevent approval of vaccines like mRNA-1083, which are designed to be compared against existing vaccines rather than placebos.

Experts have criticized this policy as unnecessary and potentially unethical, arguing that withholding effective vaccines from placebo groups exposes participants to avoidable risks. Moreover, the requirement could slow the development and availability of updated seasonal vaccines, which must rapidly adapt to evolving viral strains like those of flu and covid-19.

A complicating factor is that no mRNA-based flu vaccine has yet been approved, which may prompt the FDA to insist on placebo-controlled trials for mRNA-1083. Additionally, political skepticism toward mRNA vaccines, particularly from officials like RFK Jr., who has a history of anti-vaccine rhetoric, casts further uncertainty on the vaccine’s future. Moderna does not expect approval before 2026, pending additional data requested by the FDA.

The development of mRNA-1083 represents a significant advancement in vaccine technology, potentially streamlining immunization efforts against two major respiratory illnesses. However, regulatory and political challenges highlight the complex interplay between science, policy, and public health. Navigating these challenges is critical to ensuring timely access to innovative vaccines that can reduce disease burden and improve population health outcomes.