An outbreak of measles in Florida has grown to 10 cases. Most have been linked to an elementary school with nearly three dozen unvaccinated students. The count includes seven cases tied to the school, two in the same county, and one travel-related case in another county. The situation is likely to get worse. Florida allows nonmedical vaccine exemptions, which have been slowly increasing in the state since 2021.
This is happening in a state with a growing skepticism of vaccinations and an ongoing debate between individualism and the good of the larger population that came to a head during the COVID pandemic. But containing measles, which can spread quickly, should not be up for debate. Yet this is what is happening in Florida, and it’s putting children’s health at risk.
In response to the outbreak, the Florida Department of Health has issued a letter with a surprising new recommendation that contradicts the standards of health practice for measles outbreaks in two big ways.
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
First, in that letter, the state’s surgeon general, Joseph Ladapo—who has gone against established public health practice before—wrote that unvaccinated kids who may have been exposed to measles can continue to attend school. This is unprecedented and dangerous. Children without the prior immune exposure that vaccines provide need to be isolated for 21 days after exposure to avoid contracting and further spreading this illness. Second, despite local calls from public officials to get children vaccinated, Ladapo has failed to recommend vaccination for kids without immunity. This is troubling because unvaccinated kids can still get protection against measles if they get vaccinated within 72 hours of exposure. And if they get vaccinated within 72 hours, they can return to school as long as they don’t develop symptoms. Many parents don’t know this information, and leaving it out is deceptive.
Unvaccinated children need to stay home after measles exposure to stop transmission. Failure to do so significantly increases the chances of a prolonged outbreak.
We cannot afford that. People have forgotten how dangerous measles is because vaccines have largely wiped it out. Take a moment to remember: the virus can make kids very sick. For people without immunity, one in five who get infected will be hospitalized. Among infected children, one in 20 will develop pneumonia (the most common way measles kills young kids), one in 1,000 will develop encephalitis (inflammation of the brain, sometimes causing permanent brain damage) and one to three in 1,000 will die. And measles can cause “immune amnesia,” in which the immune system loses its ability to fight other viruses that people were previously immune to. It is extremely contagious: among unvaccinated people, nine out of 10 who are exposed will get infected.
We don’t require isolation for most viruses: if kids don’t get a flu shot, they don’t need to skip school if they were exposed to influenza. But because measles is one of the most contagious viruses known on Earth, the number of people that just one infected person can infect is much higher for measles than it is for other viruses. Viruses spread exponentially, so in a population that doesn’t have widespread immunity, just a few cases can become many very quickly.
It can be hard to contain measles. It takes five to 21 days from first exposure for symptoms to develop, so infected children are contagious up to four days before the measles rash develops, meaning they may infect others before they know they’re infected themselves. Right now, despite the frequent occurrence of small outbreaks, our comprehensive vaccination program means measles has been effectively eliminated in the U.S. It is not consistently circulating through our population. As public health experts, we and our profession want to keep it that way.
Florida’s surgeon general tries to justify the decision to let exposed kids without immunity go to school by arguing that vaccination rates in the state are high. It’s true that just under 91 percent of kindergartners in Florida are vaccinated. But 91 percent is not high enough to contain measles because the virus is so contagious. The threshold for population immunity against measles is 95 percent. The extra percentage points allows herd immunity to kick in with measles—protecting those that cannot be protected. Not having the extra protection means there are pockets in schools and communities that this virus could burn through.
Keeping kids home from school is hard but is sometimes necessary to keep them and other children healthy. Missing school is not something health officials recommend lightly. But recommendations are always grounded in trade-offs: disease severity, the potential for transmission, days of in-person schooling lost, and disruption to parents, childcare, productivity and the economy. In this case, the trade-off is containing a deadly and easily spread illness versus having unvaccinated children miss school until the disease incubation period has passed.
One of us is a parent, and the most disappointing part of the Florida Department of Health’s letter is the lack of information on actions parents can take to avoid kids missing school, especially information about getting vaccinated, even after exposure. Vaccination will help reduce the severity of symptoms, too. The window for action is small, however. Measles is not a new virus. We have been studying it for more than a century. There are reasons we have standards for dealing with the disease, and it’s a slippery slope to think otherwise.
We hope parents and the broader communities around schools are paying attention. It takes a team approach to stop infectious diseases. This can mean strengthening immunization requirements or asking for bills requiring transparency about which schools have lower vaccination rates so parents can make informed decisions. The scary question is: What happens when community responsibility breaks down? We hope that Florida’s actions do not signal that this is our future.
A version of this story appeared in the newsletter Your Local Epidemiologist.
This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.