As countries in the Northern hemisphere deal with the flu season, experts say regulation surrounding flu vaccines could be due for a shake up with new healthcare leaders set to take charge in the US.

Last month, President-elect Donald Trump appointed Robert F Kennedy Jr (RFK Jr) as the US Secretary of Health and Human Services (HHS). Soon after, Dr. Dave Weldon and Dr. Marty Makary were nominated as heads of the US Centers for Disease Control (CDC) and US Food and Drug Administration (FDA), respectively, signalling a potential new direction for US healthcare regulation.

These recent appointments have triggered discussions about changing tides in the US vaccine landscape. As part of his “Make America Healthy Again” campaign, RFK Jr has said, “If you want a vaccine, you ought to be able to get a vaccine, but you ought to know the safety profile and the risk profile of that vaccine and the efficacy of that vaccine — and that’s it.”

Weldon, a former congressman for Florida has publicly questioned vaccine safety, whilst RFK Jr has openly criticized the vaccine litigation process and the current approval process for flu vaccines amongst other things raising concerns in public health and policy circles. Meanwhile, Makary had openly opposed vaccine mandates during the Covid-19 pandemic.

“I think having one of the most prominent voices of the anti-vaccine movement in a position like Secretary of the HHS will only decrease vaccination rates,” says Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security in Maryland, US. The policy stance taken by these officials will be critical to stem vaccine hesitancy among the general public. The US Centers for Disease Control (CDC) reports that in the 2023–24 flu season, vaccination coverage with ≥1 dose of flu vaccine landed at 55.4% amongst children aged six months to 17 years old. This is the lowest vaccination rate seen in this population since the 2011-2012 flu season.

When asked about the impact of these nominations at a recent conference, Dr. Peter Marks, the director of the Center for Biologics Evaluation and Research (CBER) at the FDA said, “I don't doubt that we are going to have a very vigorous dialogue about the benefits and risks of vaccines.”

The future of flu vaccines

RFK Jr’s “long record of distrust and skepticism towards vaccines” is causing anxiety amongst public heath advocates, who expect a climate of hostility and ambivalence from the potential HHS head, says Dr. Jason Schwartz, associate professor of public health, at the Yale Institute for Global Health in New Haven, Connecticut.

The established system for flu vaccines entails advising manufacturers annually on the strains to include in the vaccines, and authorising vaccines for administration in autumn. “Those are approved for use through an expedited pathway each summer, so flu vaccines tend to be available in the US by Labor Day,” says Schwartz.

The constant need for updated flu vaccines is because of the surface antigens on the influenza virus that evolve over time, explains Dr. Jeremy Brown, a professor of respiratory infection at University College London in London UK. For this reason, “you need to have a new vaccine against a new virus every year,” he adds. At the same time, the established flu vaccines are very safe and tolerable and new clinical trials would likely only identify a rare few side effects, says Brown.

RFK Jr has criticised the vaccine review system, casting aspersions on the amount of data on the vaccines on the US market, suggesting that new efficacy trials may be needed for updated vaccines.

However, Schwartz says, given the decades of evidence about the safety of the influenza vaccine platform, there is enough reason to be confident that replacing the strains to match those likely to circulate during that season does not transform the overall profile of how vaccines work.

Also, running new large safety and efficacy trials would be unrealistic as millions of people would need to be enrolled, says Brown. “If you do a trial, by the time you can analyse results the next flu season has begun, so the trial is pointless, because you will need a new vaccine for the next season anyway,” he adds. Schwartz agrees, adding that requiring this data would make the update system “impractical” and would likely be “impossible”. Moreover, the need for full comprehensive trials would force scientists to anticipate upcoming strains much earlier, which would lead to prediction errors, he adds. Even Marks has said that for diseases like the flu and Covid-19, “you simply can’t generate placebo-controlled gold-standard data”.

Expectations for upcoming vaccine policy

Other factors may also influence vaccine usage. The current US CDC recommendations for flu season encourage all individuals aged six months or older to get a flu vaccine by the end of October with rare exceptions. “For many states, there are annual requirements for children, particularly in daycare, under the age of five to get an annual flu vaccine,” says Schwartz. In the US, the RSV vaccine is given year-round, but there has been a general push to give influenza and Covid-19 vaccines at the same time as the harmonized schedule improves vaccination rates, says Adalja. “Flu and Covid-19 tend to have overlap in their activity and get worse as it gets colder in the northern hemisphere. In the US, in our winter months and in September and October, you start to get people interested in getting vaccinated,” explains Adalja.

The direct impact of other speculated actions on vaccine research also remains to be seen. The National Childhood Vaccine Injury Act of 1986 prevents individuals filing lawsuits to vaccine companies for side effects, allowing them to claim compensation from a separate scheme. Adalja predicts that any significant shift in the litigation process could have a major negative impact on vaccine innovation in the US. “Vaccines are not a very lucrative prospect for pharmaceutical companies to begin with, and if now they are facing endless lawsuits and frivolous lawsuits, why would they invest in vaccines which they don't get as high of a return on investment as they do, for example, cancer treatments,” says Adalja.

Since the CDC’s advisory committee on Immunisation Practises is under the purview of HHS, Adalja speculates that RFK Jr’s nomination could create barriers for vaccine approval. However, despite the shifting perspective, Marks offers a tempered prognosis saying says the new leadership may not change how the FDA assesses of flu vaccines. “I do think we could be asked to be more transparent, and we may have to have more advisory committees and more discussions around vaccines, but I don't necessarily view that as a bad thing,” said Marks.