Cammi Norwood's son Mason was jumping with joy at the thought of starting public school next year in Palmetto, Florida.
The four-year-old, who was diagnosed with Stage 4 kidney disease at birth, has spent two healthy years without any hospital visits, and is eager to be in class with friends, Ms Norwood said.
But the 32-year-old mother is beginning to reconsider sending her immunocompromised son to school, after Florida's surgeon general last week announced he would try to end vaccine mandates in the state, including those for school children.
It's just scary, Ms Norwood said. If these kids aren't vaccinated … he can get very, very sick if someone were to come in with the measles.
Medical experts and some parents worry the surgeon general's move will threaten the health of vulnerable children like Mason, setting the stage for a new era of infectious disease, driven by lower vaccine rates.
We'll end up having pockets of outbreaks of different types of infectious diseases, Florida's former surgeon general, Scott Rivkees, told the BBC. Individuals who are older, immunocompromised adults and children who may have cancer, for example, are going to be afraid to go out into public.
If Florida goes ahead, it would be one of the first states to officially do away with childhood vaccination mandates, which have long been a fixture in parents' back-to-school plans. In April, Idaho's governor signed a law loosening vaccine requirements.
These moves come as Health Secretary Robert F Kennedy Jr, a vaccine sceptic, undertakes remaking US vaccine policy, and the nation's public health agency, the Centers for Disease Control and Prevention (CDC), is in turmoil.