Waning immunity and low vaccination rates are driving a U.S. pertussis rise, especially among unvaccinated people and infants.

Waning immunity from past vaccinations and declining vaccination rates are contributing to a rise in pertussis cases across the U.S., according to public health officials. The increase has led to outbreaks in multiple states, with higher infection rates among unvaccinated individuals and infants too young to be fully protected. Health experts are urging booster shots and improved immunization coverage to curb the spread.