Falling Vaccinations Contribute to Rising Pertussis Rates

New data from the Centers for Disease Control and Prevention (CDC) show significant spikes in pertussis cases compared to last year, especially in several urban areas including New York, Illinois, Florida, and Colorado. Cases are rising at the same time that rates of vaccination have been on the decline.

Notably, the current pertussis case count in Illinois as of September 21, 2024, was five times higher than the total cases in 2023 (1058 vs 50). New York City alone had reported 624 cases as of September 21, compared with 38 cases in 2023. 

Additional data from the CDC on vaccination coverage and exemptions of school-aged children showed an increase from 3.0% last year to 3.3% in 2024 of children who were exempted from recommended vaccination requirements. Although nearly 93% of kindergarteners in the United States received recommended vaccines (including Tdap), similar to last year, this number shows a steady decline from 94% in the 2021-2021 school year and 93% in the 2021-2022 school year, according to previous CDC reports.

What’s Happening in the Clinic

Clinical experience and the most recent CDC data point to under vaccination as a driver of the increased pertussis cases this year, said David J. Cennimo, MD, associate professor of medicine & pediatrics in the division of infectious disease at Rutgers New Jersey Medical School, Newark, New Jersey, in an interview.

Although the pertussis vaccination rates in infancy are still very good, clinicians are seeing a drop-off in school-aged children and adults, and the lingering anti-vaccine efforts from the COVID-19 pandemic period are undoubtedly playing a part, said Cennimo. “Unfortunately, pertussis is contagious, and the vaccine effectiveness wears off. Having decreased numbers of people protected results in more rapid spread,” he said. 

Cennimo agreed that the number of cases in the United States is underreported, and even higher than the data suggest. “I’m sure of it; the initial clinical presentation may be mistaken for a viral upper respiratory tract infection (common cold),” he told Medscape Medical News.

Many older children and adults with pertussis do not manifest the classic “whooping cough” seen in infants and young children, so making a clinical diagnosis can be difficult, he said. “One classical component of the illness is a prolonged cough. I have wondered if some people now reporting a lingering cough had pertussis that was missed,” Cennimo noted. 

“Clinicians should stress the value of boosters in a vaccine-preventable illness where we know immunity wanes overtime,” Cennimo said. “We have a great remedy in the Tdap vaccine, which we should all be getting very 10 years,” he said. 

He also emphasized that clinicians remind pregnant women of the current recommendations to receive the Tdap vaccine for every pregnancy. “Vaccination during pregnancy is the best way to protect both the pregnant person and the newborn. 

Even for the vaccine hesitant, this vaccine has a long track record of safety so should not be a significant concern,” he said.

The ultimate take-home message is not a new one, and applies to all illnesses, Cennimo told Medscape. Simply put, “Stay home if you are sick. Social distancing is not just for COVID-19,” he said.

Cennimo had no financial conflicts to disclose.