LAS VEGAS — A new combined vaccine for COVID-19 and influenza is on the brink of approval, following promising results from a phase 3 clinical trial. The trial, funded by Moderna, revealed that the new shot outperformed existing standalone vaccines for both viruses, as detailed in a study published on May 7, 2025, in the Journal of the American Medical Association.
The trial involved over 8,000 adults aged 50 and older, who were enrolled in October and November 2023. According to NBC News, the study compared the new combined vaccine against Moderna’s existing COVID-19 vaccine and the flu shot Fluarix for participants aged 50 to 64. For those aged 65 and older, the new vaccine was compared to the COVID-19 vaccine and a stronger flu shot known as Fluzone.
Participants were administered either the existing vaccines or the new combination vaccine alongside a placebo shot. The findings indicate that the new vaccine generated a stronger immune response against COVID-19 and most strains of flu compared to the standalone vaccines.
Side effects reported during the trial included injection site pain, fatigue, and headaches, which are common reactions to vaccinations. Dr. Greg Poland, a vaccine response expert at the Mayo Clinic who was not involved in the study, expressed skepticism about the potential popularity of a combined shot, noting that while influenza occurs seasonally, COVID-19 has been circulating year-round. This raises questions about how to effectively time vaccinations to maintain robust protection.
Moreover, while the initial findings are encouraging, the U.S. Food and Drug Administration (FDA) has requested further data demonstrating how well the new vaccine protects against infection and hospitalization. Moderna had initially aimed for approval sooner but recently pushed its target date to 2026 after the FDA's request for more direct efficacy measures.
In the wake of this development, Moderna President Stephen Hoge reassured investors during an earnings call that discussions with the FDA have been productive, describing the situation as "business as usual." However, Health Secretary Robert F. Kennedy Jr. has publicly questioned the safety of mRNA vaccines, adding another layer of complexity to the ongoing vaccine discourse.
As the landscape of vaccine development continues to evolve, Moderna's combined shot could potentially improve vaccination rates, as noted by the researchers. By utilizing messenger RNA (mRNA) technology, which has been successfully employed in approved COVID-19 and RSV vaccines, Moderna believes it can accelerate the production of flu vaccines compared to traditional methods that typically rely on chicken eggs or large cell cultures.
Despite the promising data, Dr. Poland emphasized the need for additional evidence on the vaccine's effectiveness in preventing serious illness. The current findings are based on antibody measurements taken from participants' blood after 29 days, indicating short-term protection against diseases.
Last week, the FDA also prompted Novavax to conduct a new clinical trial for its protein-based COVID-19 vaccine, further complicating the approval landscape for various vaccine candidates. This request came after Novavax received full approval for its vaccine, highlighting the regulatory hurdles that companies face in bringing new products to market.
As the pandemic continues to shape public health policy and vaccine development strategies, the potential approval of Moderna's combined vaccine may represent a significant step forward in the fight against respiratory viruses. The ongoing dialogue among health experts, regulators, and the public will be crucial in determining the future of vaccination strategies aimed at protecting against both COVID-19 and influenza.
