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.