The American Medical Association, the largest group of physicians in the US, sent a letter to Republicans in the House of Representatives, warning them against eliminating a key fund that’s used to prevent outbreaks in America.

The Republican bill to repeal and replace Obamacare will not only make health insurance more expensive for millions of Americans, it will also cut the Public Health and Prevention Fund. That means taking a 12% bite out of the US Centers for Disease Control’s budget—the part dedicated to preventing disease outbreaks and a host of other health calamities, like childhood lead poisoning.

The Prevention Fund allocates $890 million to the CDC to create better infrastructure for identifying disease outbreaks before they happen, and addressing them before they spread. The fund dedicated $210 million to the CDC’s immunization program in 2015, for example.

Another $3 billion is allocated through the Prevention Fund to support state health agencies that deal in community-level disease prevention, bioterrorism prevention, pandemic response, and other health emergency response, according to a report from advocacy group Trust for America’s Health. Programs for preventing lead poisoning, preventing the spread of viral hepatitis, reducing prescription overdoses, and screening for breast and cervical cancer are all covered under the Prevention Fund.

US president Donald Trump has yet to appoint an administrator to lead the CDC, a chronically underfunded agency which has handled 750 outbreaks in the last two years alone. With significant cuts to the already-beleaguered agency, the new administration is poised to weaken America’s ability to prevent outbreaks.