MISSOULA, Mont. (AP) — Missoula City-County Health Department officials say the number of cases of whooping cough in the Missoula area has topped 100, including many people who have been vaccinated.

Department Director Ellen Leahy says protection from the vaccine wanes over time.

Vaccines against whooping cough, or pertussis, are given as a series between 2 months and 18 months of age and another around age 5. A booster is given to preteens. The Centers for Disease Control says women should get a booster during the third trimester of each pregnancy.

Missoula County has confirmed 103 cases of whooping cough through Tuesday morning and was hiring more nurses to help with testing.

Leahy tells KGVO-AM that 975 tests have been submitted and another 58 are pending at the state lab.