Moderna has initiated a large-scale clinical trial for an mRNA-based vaccine targeting avian influenza in humans, following the withdrawal of significant federal funding from the Department of Health and Human Services (HHS). The vaccine leverages messenger RNA technology, the same platform used in widely distributed COVID-19 vaccines, which has been both lauded for its rapid development capabilities and scrutinized by some government officials.

The funding pullback occurred last year under HHS Secretary Robert F. Kennedy Jr., who canceled hundreds of millions of dollars in financial support previously committed to Moderna’s vaccine development efforts. This decision came amid debates over the effectiveness and safety of mRNA vaccines for respiratory illnesses such as flu and COVID-19. According to Moderna spokesperson Chris Ridley, the loss of government backing caused several months’ delay as the company sought alternative financing.

In response, the Coalition for Epidemic Preparedness Innovations (CEPI), an international vaccine accelerating partnership, has stepped in with an investment of up to $54.3 million to facilitate Moderna’s bird flu vaccine efforts. Moderna announced on Tuesday that initial participants in the Phase 3 trial have been vaccinated in the United States and the United Kingdom. The study plans to enroll approximately 4,000 adults aged 18 and older.

The vaccine candidate had previously demonstrated promising interim results in an early-stage trial with around 300 healthy adults, showing a favorable immune response and safety profile. Stéphane Bancel, Moderna’s CEO, described the trial’s launch as a critical step toward enhancing global readiness for future pandemics. He emphasized the platform’s efficiency and scalability as key assets in addressing emerging infectious threats.

HHS has defended its decision to discontinue funding last year, citing a “rigorous review” process that deemed mRNA technology insufficiently validated for broad use against rapidly mutating respiratory viruses. A department spokesman, Andrew Nixon, noted that HHS remains interested in mRNA applications for difficult-to-treat cancers and highlighted ongoing investments in public-private partnerships within that domain. Nixon also stated that mRNA vaccine developers have received extensive government subsidies, prompting a strategic realignment of resources toward other emerging technologies.

The debate over mRNA vaccines’ cost-effectiveness and scientific merit continues within federal health circles. Food and Drug Administration Commissioner Marty Makary expressed enthusiasm for mRNA innovations but argued that companies profiting from the COVID-19 vaccine rollout should assume greater responsibility for funding their own research. Makary suggested redirecting taxpayer dollars toward underfunded areas lacking commercial investment.

Medical experts broadly recognize that mRNA vaccines provide a safe and effective mechanism for stimulating immune responses by delivering genetic instructions to cells, enabling faster vaccine development compared to traditional methods reliant on weakened or inactivated viruses. Moderna’s current trial for the bird flu vaccine represents a test of this technology’s adaptability to new viral threats amid evolving public health priorities.