The rate of pertussis has fallen sharply in Maine, which not long ago had one of the highest rates of the infectious disease in the country.
Pertussis is also called whooping cough and it's an infection that causes a severe, hacking cough and can be especially dangerous to babies. Maine had the second-highest rate of the disease in the U.S. in 2019 at more than 28 cases per 100,000 residents.
The state is on track to record about seven cases per 100,000 this year, the Portland Press Herald reported. That figure is much closer to the national average.
The decline in pertussis overlapped with the start of COVID-19 pandemic and mitigation measures such as mask mandates and social distancing.
The state's rate of immunization for pertussis could also be a factor. Maine took away philosophical and religious exemptions from school vaccine requirements with a 2019 law that was upheld by voters in a March 2020 referendum.
Maine Center for Control and Prevention Director Dr. Nirav Shah said it will take time to determine if the school mandate is "a minority factor or a majority factor."