DETROIT (AP) — Public health officials worry future outbreaks of vaccine-preventable diseases could emerge in Michigan as vaccination rates have dramatically fallen during the coronavirus pandemic.

Vaccination rates for children 18 and younger fell by more than 20%, according to a study published by the federal Centers for Disease Control and Prevention. Measles vaccinations in particular, dropped about 76% among 16-month-old children. Other diseases include mumps, rubella, diphtheria, tetanus and pertussis, or whooping cough.

Many parents worried about the virus have kept their young children home, doctors say.

“I’m extremely concerned that anytime we see a drop-off in our vaccine rates that it does leave the door open for a potential outbreak,” Bob Swanson, director of the division of immunization at the Michigan Department of Public Health told The Detroit News.

Researchers compared how many kids have been vaccinated this May versus May rates from 2016-2019, and found fewer than half of babies who are currently 5 months old were up-to-date on their immunizations compared to prior years. They relied on data from the Michigan Care Program Registry, which tracks immunizations statewide.

Dr. David Obudzinski, a pediatrician, said parents began canceling appointments in March, when stay-at-home orders were issued. His Bingham Farms practice has remained open throughout the pandemic but was forced to reduce its hours due to lack of patients.

“My fear is that we’re going to have a group of kids who are not protected at an age where they need to have the protection,” he said.

Measles, for examples, usually include mild symptoms, but those symptoms can be deadly in babies who cannot be immunized until they’re a year old, according to health officials.

“We need to be sure that everybody gets caught up on their immunizations that they may have fallen behind on so that we can assure that everybody is protected from vaccine-preventable diseases,” Swanson said.