The Biden administration announced on Wednesday that it will start offering coronavirus vaccine booster shots next month, recommending that Americans who received their original doses from Pfizer or Moderna to seek a booster eight months after their initial shot.

This decision is a mistake. Not only does it risk depriving millions throughout the world of the vaccine, but there also is no evidence that additional shots meaningfully reduce death or hospitalization from COVID-19 for healthy Americans. Far better would be to wait for solid trial data on booster shots.

U.S. health officials ought to heed the warning from Tedros Adhanom Ghebreyesus, director general of the World Health Organization, that the world had fallen into a state of “vaccine apartheid.” High-income countries have used bilateral contracts with vaccine manufacturers to achieve vaccination rates as much as 50 times that of low-income countries. A campaign for boosters could lock in that apartheid. This profound global inequity would not only be a humanitarian disaster, but also a significant long-term risk for Americans, as scientists agree that accelerating global vaccination is the only way to prevent the formation of deadly new variants.

The administration points to recent reports from the Centers for Disease Control and Prevention showing that the efficacy of the vaccines against mild infection is waning to justify boosters. This is an important concern, but the same reports demonstrate full vaccination is still highly protective against severe COVID-19 disease. The United States should address this issue with the same thoughtfulness and regulatory scrutiny as initial vaccine approval. That means booster shots should be subject to a randomized, controlled trial comparing three doses to two doses with power to detect significant differences in hospitalizations or deaths.

With the delta variant running rampant through the unvaccinated population, such a trial, similar to the vaccine trials for initial approval, would be easy to complete. In fact, Pfizer has just such a trial ongoing, the Food and Drug Administration should require they complete it before amending the vaccine Emergency Use Authorization. This trial should be the first in an ongoing series of adaptive clinical trials, using the power of randomization to determine the optimal dosing strategy for vaccines over time. And these trials should examine actual outcomes such as hospitalization — not “surrogate” endpoints such as antibody levels.

That boosting all adults would be inappropriate without compelling evidence of improved efficacy does not mean the CDC was wrong to provide targeted booster access for small populations, such as organ transplant recipients on immunosuppressive drugs. Unlike the general population, these patients have a poor immune response to two doses and face a high risk of hospitalization despite two-dose vaccination. Observational data show a third dose is needed to give antibodies to immunocompromised patients, making access to boosters a reasonable precautionary approach. Just as importantly, offering the more than 50 million vaccines already distributed and sitting in freezers throughout the United States to these populations presents little risk of global deprivation compared to purchasing millions of additional doses, not yet distributed to states, for use as boosters in the general population.

Moderna and Pfizer are already profiting from their vaccines to the tune of hundreds of millions of dollars. The United States must now decide how to incentivize the next step for these companies, as they can produce a billion more doses than the U.S. population needs by the end of the year. Should we pay high prices for biyearly boosters for the 190 million and counting vaccinated Americans, which will require hundreds of millions of additional doses? Or should we build on the 100 million doses we have donated globally so far and pledge at least 10 million additional doses per week to low-income countries? The latter strategy would ensure domestic supply for unvaccinated Americans while we await evidence that boosters meaningfully protect healthy, fully vaccinated Americans.

Finally, the administration made a mistake by letting its booster recommendations become public through a series of anonymous leaks to the media. Other major vaccine decisions came after careful deliberation by both the FDA and CDC, relying heavily on rigorous analysis and advice from the Advisory Committee for Immunization Practices. Perhaps this was done as a trial balloon to assess the public’s reaction. But that’s not how public health should be done.

Based on the suggested eight-month interval for third doses, the United States will need more than 120 million additional mRNA doses by the end of 2021. That’s enough doses to vaccinate the population of COVID-decimated Botswana 26 times over. Will already-protected Americans line up to boost their antibodies while the virus rages and mutates overseas, evidence be damned? Or will we demand that our government recognize that global pandemics require global solutions? Vaccinating the unvaccinated, not buffing up the antibody levels of the already protected, is our way out of the pandemic.

William F. Parker is an assistant professor of pulmonary and critical care medicine at the University of Chicago and assistant director of the MacLean Center for Clinical Medical Ethics. Govind Persad is an assistant professor at the University of Denver Sturm College of Law and Greenwall Foundation Faculty Scholar in Bioethics.