As Florida moves toward eliminating school vaccine mandates, measles tops the list of diseases experts fear could return, bringing lasting public health consequences. Philip Verhoef, an adult and pediatric critical care physician and clinical assistant professor at the University of Hawaiʻi at Mānoa John A. Burns School of Medicine, explains the risks.
Q: What are the ramifications of Florida dropping its vaccine mandate?
Verhoef: We’re already seeing a steady rise in measles cases in the U.S. and globally. Eliminating vaccine requirements makes it easier for children to go unvaccinated, increasing the likelihood of outbreaks. As measles spreads, immune amnesia could make children more susceptible to other infections they were previously protected against.
Even though most families—80 to 90%—still choose to vaccinate, lowering overall immunization rates threatens herd immunity. That not only puts unvaccinated children at risk but also increases the likelihood that those who cannot be vaccinated for medical reasons could be exposed to serious diseases.
Q: What does this mean for unvaccinated children?
Verhoef: Children who get measles–and have not been vaccinated–face higher risks for other infections for years afterward. Even if they survive measles itself, their immune system’s memory is impaired. This means illnesses they were previously protected against, either through prior infection or vaccination, could now strike them again.
Prevention is critical: once measles occurs, the long-term consequences on health are unavoidable.
—Philip Verhoef
Q: What are the complications from measles?
Verhoef: Measles is more than just a rash and fever. Children and adults can develop cough, runny nose, and high fever, but severe complications are possible, including pneumonia, swelling of the brain (encephalitis), or even death in rare cases. Measles is extremely contagious, so even one infected child in a school can quickly lead to an outbreak. Beyond these immediate effects, measles can have long-term consequences on the immune system.
Learn more about the measles vaccine.
Q: How does measles affect immune memory?
Verhoef: Measles is unusual because it actually infects the cells responsible for maintaining immune memory. When this happens, the immune system essentially “forgets” previous infections or vaccinations. For example, a child who had chickenpox or strep immunity may lose that protection after a measles infection. This phenomenon—called immune amnesia—is unique to measles among common childhood viruses and can leave a child vulnerable to many diseases they were previously protected against.
Q: Why is the immune system’s “memory” important?
Verhoef: Our immune system develops a memory every time we encounter an infection. This memory allows the body to respond quickly and effectively if the same virus or bacteria appears again. Vaccines work by stimulating this memory without causing the disease itself, so the body “remembers” how to fight off specific infections, such as measles, chickenpox or influenza.
Q: If mandates are reinstated, can the damage be undone?
Verhoef: For children who have already had measles, it’s too late to reverse the immune system’s memory loss. Vaccination after infection won’t restore protection against other diseases that measles has erased from the immune system. Prevention is critical: once measles occurs, the long-term consequences on health are unavoidable.
