Five years ago, volunteers rolled up their sleeves in the first clinical trial of a vaccine against COVID-19, as the new pandemic surged around them.

By a year later, 66 million American adults had gotten at least one dose of a COVID-19 vaccine, at no cost to them.

Now, a study shows how wise that national investment in testing, buying and delivering those first vaccines was.

In all, the national vaccine strategy more than paid for itself after just one year, according to the findings published in the journal Vaccine by a team led by University of Michigan researchers.

Because the vaccines reduced how many people developed serious illness or died, the United States saved more money than it spent, the study concludes.

The analysis includes not only the cost of care for COVID-19 but also the cost of testing and treating people, of treating post-COVID conditions as well as rare vaccine reactions, and productivity costs such as lost workdays when someone became sick or died.

Even without counting lost productivity, the national COVID-19 vaccine effort saved money for most adult age groups purely by avoiding medical costs, the study concludes.

Overall, among all adults over age 40, the nation saved more in avoided medical costs than it spent on the vaccine effort.

Even among adults age 18 to 39, who are less likely to get seriously ill from COVID-19, the vaccination effort cost slightly more than the total medical costs avoided, but was still cost-effective by national standards.

When lost productivity is included, vaccinating these younger adults was cost-saving.

The U-M team that performed the study has also presented findings about the cost-effectiveness of several vaccines to meetings of Centers for Disease Control and Prevention’s Advisory Committee for Immunization Practices, which creates recommendations for vaccine use.

“All in all, we can safely say that this was a prudent investment for the American people, using a really conservative analysis,” said Lisa Prosser, Ph.D., first author of the study and professor at the U-M Medical School and School of Public Health.

“From a broader societal economic perspective, and from the perspective of medical care costs, the federal government’s decision to accelerate vaccine testing, buy large quantities of vaccine, and support the cost of vaccination in many settings was wise.”

Prosser and senior author David Hutton, Ph.D., of the U-M School of Public Health worked to develop and test the model, which is based on research findings by many other teams that have studied aspects of COVID-19.

The model includes everything from the cost of the vaccine itself, to home or lab tests for the virus, to the likelihood of suffering any level of COVD-19 illness or vaccine reaction, to the typical cost of receiving care at any level of illness, to the number of days of work lost for different levels of illness.

The researchers included post-COVID conditions, also called Long COVID or PASC for Post-Acute Sequelae of COVID-19.

The model uses conservative estimates, so the size of the savings may actually be even larger than the study reports, Prosser notes.

For instance, it does not include the lost productivity of people who took time off work to care for a sick adult family member, patients’ out-of-pocket costs for treatment, or transportation to get to medical care.

Nor does It include the cost of the basic laboratory science funded by the federal government over two decades that laid the groundwork for the two mRNA vaccines made by Pfizer and Moderna.

Prosser, Hutton and their colleagues have done additional economic modeling of waves of vaccination after 2021 in collaboration with CDC.

They hope to create a model for the updated version of the vaccines that are expected to roll out this coming fall, but this will depend on CDC funding and data.

Prosser notes that as of his winter, widespread vaccination and improved treatment have decreased the death toll from COVID-19, and the number of cases severe enough to need emergency or hospital care.

Still, between 800 and 1,000 people have died of COVID-19 every week of 2025 for which full data are available, and about 1% of all emergency department visits in recent months have been for illness diagnosed as COVID-19. 

She notes that the current CDC recommendation is for everyone over the age of 6 months to get at least one dose of one of the three updated vaccines that became available in September 2023 and are now updated annually.

So far, about 30 million have done so, including about 30% of people age 65 and older, who are at highest risk of severe COVID-19 if they become infected.

For people who are age 65 and older, or immunocompromised because of a health condition or treatment, the CDC recommends a second dose of the current vaccine six months after the first.

That means that people who got the updated vaccine soon after it came out in September should now go get a second dose.

Additional authors: In addition to Prosser and Hutton, the study’s authors are Janamarie Perroud, Grace S. Chung, Acham Gebremariam, Cara B. Janusz, Kerra Mercon, Angela M. Rose, Anton L.V. Avanceña and Ellen Kim DeLuca. All the authors are or were formerly affiliated with the U-M School of Public Health or the Susan B. Meister Child Health and Evaluation Research Center (CHEAR), which is based in the U-M Medical School’s Department of Pediatrics. Prosser and Hutton are members of the U-M Institute for Healthcare Policy and Innovation.

Funding/disclosures: The study was funded by CHEAR.

Paper cited: “The cost-effectiveness of vaccination against COVID-19 illness during the initial year of vaccination,” Vaccine. DOI: 10.1016/j.vaccine.2025.126725

Sign up for Health Lab newsletters today. Get medical tips from top experts and learn about new scientific discoveries every week.

Sign up for the Health Lab Podcast. Add us wherever you listen to your favorite shows.