The administration of U.S. President Donald Trump has announced the cancellation of 22 federal contracts related to mRNA-based vaccine development, a decision that marks a significant policy shift in the nation’s public health approach and has sparked renewed debate over vaccine safety and science.
The move was unveiled by Health and Human Services (HHS) Secretary Robert F. Kennedy Jr., who said the decision followed a comprehensive review of scientific data and expert input. The cancelled contracts, worth nearly $500 million, had been allocated for projects including Moderna’s bird flu vaccine and several proposals from major pharmaceutical companies such as Pfizer and Sanofi.
“We reviewed the science, listened to the experts, and acted,” Kennedy said in a statement. “The data show these vaccines fail to protect effectively against upper respiratory infections like COVID and flu. We’re shifting that funding toward safer, broader vaccine platforms that remain effective even as viruses mutate.”
According to HHS, some late-stage vaccine projects were spared cancellation to preserve previous taxpayer investments. However, the department is pivoting its funding away from mRNA technology, which had formed the backbone of the U.S. COVID-19 vaccine strategy during the pandemic.
mRNA vaccines, which use genetic material to instruct cells to produce an immune response, gained global prominence during the COVID-19 crisis. The technology helped deliver vaccines at unprecedented speed, with Operation Warp Speed — a Trump-era initiative — fast-tracking development and distribution. Its pioneers, Drs. Katalin Karikó and Drew Weissman, received the Nobel Prize in 2023 for their groundbreaking work.
Despite widespread praise from the scientific community, Secretary Kennedy, a longtime critic of vaccines, has cast doubt on mRNA safety and questioned its effectiveness. Since his appointment, Kennedy has overhauled federal vaccine policy, including dismissing a long-standing panel of scientific advisers and replacing it with appointees more aligned with his views.
One of the panel’s first decisions was to ban a widely used vaccine preservative, despite a strong safety record supported by decades of research.
Critics warn that such decisions could impact national immunisation rates. Recent data from the Centers for Disease Control and Prevention (CDC) reveal declining vaccination coverage among preschoolers. In the 2024–25 school year, the national MMR (measles, mumps, rubella) vaccination rate fell to 92.5%, down from 95.2% in 2019–2020 — a concerning drop as measles cases rise across the country.
Texas, the current epicentre of a growing measles outbreak, has seen its MMR coverage fall to 93.2%, below the 95% threshold needed for herd immunity, according to the CDC.
An HHS spokesperson acknowledged the declining rates but maintained that “a majority of children continue to receive routine immunisations.” The spokesperson added, “The decision to vaccinate is a personal one. Parents should consult their health care providers on options for their families.”
The CDC also reported an increase in exemptions from one or more vaccines, which rose to 3.6% in the current school year. In 17 states, exemption rates now exceed 5%.
As the Trump administration distances itself from mRNA-based vaccines, health experts warn that reversing public trust in proven vaccine technologies could have lasting public health consequences — particularly as new infectious disease threats continue to emerge.
