With a brief memo, Florida Surgeon General Joseph Ladapo has subverted a public health standard that’s long kept measles outbreaks under control.

On Feb. 20, as measles spread through Manatee Bay Elementary in South Florida, Ladapo sent parents a letter granting them permission to send unvaccinated children to school amid the outbreak.

The Department of Health “is deferring to parents or guardians to make decisions about school attendance,” wrote Ladapo, who was appointed to head the agency by Florida Gov. Ron DeSantis, whose name is listed above Ladapo’s in the letterhead.

Ladapo’s move contradicts advice from the Centers for Disease Control and Prevention.

“This is not a parental rights issue,” said Scott Rivkees, Florida’s former surgeon general who is now a professor at Brown University. “It’s about protecting fellow classmates, teachers, and members of the community against measles, which is a very serious and very transmissible illness.”

Most people who aren’t protected by a vaccine will get measles if they’re exposed to the virus. This vulnerable group includes children whose parents don’t get them vaccinated, infants too young for the vaccine, those who can’t be vaccinated for medical reasons, and others who don’t mount a strong, lasting immune response to it. Rivkees estimates that about a tenth of people in a community fall into the vulnerable category.

The CDC advises that unvaccinated students stay home from school for three weeks after exposure. Because the highly contagious measles virus spreads on tiny droplets through the air and on surfaces, students are considered exposed simply by sitting in the same cafeteria or classroom as someone infected. And a person with measles can pass along an infection before they develop a fever, cough, rash, or other signs of the illness. About 1 in 5 people with measles end up hospitalized, 1 in 10 develop ear infections that can lead to permanent hearing loss, and about 1 in 1,000 die from respiratory and neurological complications.

“I don’t know why the health department wouldn’t follow the CDC recommendations,” said Thresia Gambon, president of the Florida chapter of the American Academy of Pediatrics and a pediatrician who practices in Miami and Broward, the county affected by the current measles outbreak. “Measles is so contagious. It is very worrisome.”

Considering the dangers of the disease, the vaccine is incredibly safe. A person is about four times as likely to die from being struck by lightning during their lifetime in the United States as to have a potentially life-threatening allergic reaction to the measles, mumps, and rubella vaccine.

Nonetheless, last year a record number of parents filed for exemptions from school vaccine requirements on religious or philosophical grounds across the United States. The CDC reported that childhood immunization rates hit a 10-year low.

In addition to Florida, measles cases have been reported in 11 other states this year, including Arizona, Georgia, Minnesota, and Virginia.

Only about a quarter of Florida’s counties had reached the 95% threshold at which communities are considered well protected against measles outbreaks, according to the most recent data posted by the Florida Department of Health in 2022. In Broward County, where six cases of measles have been reported over the past week, about 92% of children in kindergarten had received routine immunizations against measles, chickenpox, polio, and other diseases. The remaining 8% included more than 1,500 kids who had vaccine exemptions, as of 2022.

Broward’s local health department has been offering measles vaccines at Manatee Bay Elementary since the outbreak began, according to the county school superintendent. If an unvaccinated person gets a dose within three days of exposure to the virus, they’re far less likely to get measles and spread it to others.

For this reason, government officials have occasionally mandated vaccines in emergencies in the past. For example, Philadelphia’s deputy health commissioner in 1991 ordered children to get vaccinated against their parents’ wishes during outbreaks traced to their faith-healing churches. And during a large measles outbreak among Orthodox Jewish communities in Brooklyn in 2019, the New York City health commissioner mandated that anyone who lived, worked, or went to school in hard-hit neighborhoods get vaccinated or face a fine of $1,000. In that ordinance, the commissioner wrote that the presence of anyone lacking the vaccine in those areas, unless it was medically contraindicated, “creates an unnecessary and avoidable risk of continuing the outbreak.”

Ladapo moved in the opposite direction with his letter, deferring to parents because of the “high immunity rate in the community,” which data contradicts, and because of the “burden on families and educational cost of healthy children missing school.”

Yet the burden of an outbreak only grows larger as cases of measles spread, requiring more emergency care, more testing, and broader quarantines as illness and hospitalizations mount. Curbing a 2018 outbreak in southern Washington with 72 cases cost about $2.3 million, in addition to $76,000 in medical costs, and an estimated $1 million in economic losses due to illness, quarantine, and caregiving. If numbers soar, death becomes a burden, too. An outbreak among a largely unvaccinated population in Samoa caused more than 5,700 cases and 83 deaths, mainly among children.

Ladapo’s letter to parents also marks a departure from the norm because local health departments tend to take the lead on containing measles outbreaks, rather than state or federal authorities. In response to queries from KFF Health News, Broward County’s health department deferred to Florida’s state health department, which Ladapo oversees.

“The county doesn’t have the power to disagree with the state health department,” said Rebekah Jones, a data scientist who was removed from her post at the Florida health department in 2020, over a rift regarding coronavirus data.

DeSantis, a Republican, appointed Ladapo as head of the state health department in late 2021, as DeSantis integrated skepticism about COVID vaccines into his political platform. In the months that followed, Florida’s health department removed information on COVID vaccines from its homepage, and reprimanded a county health director for encouraging his staff to get the vaccines, leading to his resignation. In January, the health department website posted Ladapo’s call to halt vaccination with COVID mRNA vaccines entirely, based on notions that scientists call implausible.

Jones was not surprised to see Ladapo pivot to measles. “I think this is the predictable outcome of turning fringe, anti-vaccine rhetoric into a defining trait of the Florida government,” she said. Although his latest decision runs contrary to CDC advice, the federal agency rarely intervenes in measles outbreaks, entrusting the task to states.

In an email to KFF Health News, the Florida health department said it was working with others to identify the contacts of people with measles, but that details on cases and places of exposure were confidential. It repeated Ladapo’s decision, adding, “The surgeon general’s recommendation may change as epidemiological investigations continue.”

For Gambon, the outbreak is already disconcerting. “I would like to see the surgeon general promote what is safest for children and for school staff,” she said, “since I am sure there are many who might not have as strong immunity as we would hope.”

KFF Health News, formerly known as Kaiser Health News (KHN), is a national newsroom that produces in-depth journalism about health issues and is one of the core operating programs at KFF — the independent source for health policy research, polling, and journalism.