More than 8,000 cases of pertussis, or whooping cough, have been reported in the U.S. so far in 2025, more than double the amount reported in the same period last year, according to CDC data.
Four things to know about the surge in cases:
1. Cases of the bacterial infection have been on the rise in recent years, largely driven by falling vaccination rates and waning immunity among adolescents, according to infectious disease experts.
“We have clear indication that our vaccine rates are falling,” Sapna Singh, MD, chief medical officer of pediatrics at Houston-based Texas Children’s, told NBC News. “Look at the West Texas measles outbreak.”
Since the start of the year, the CDC has confirmed more than 800 measles cases in 24 states, the majority of which are linked to an ongoing outbreak in West Texas. Most cases have occurred among individuals who were unvaccinated.
2. In 2024, more than 35,000 whooping cough cases were reported in the U.S. — a decade high. This figure also marks a more than fourfold increase relative to 2023. If cases continue to grow at current rates this year, researchers estimate the U.S. will see the highest number of infections since vaccination was introduced in 1948.
3. Vaccination rates for pertussis have decreased since the COVID-19 pandemic. The national rate among kindergartners fell to 92.3% in the 2023-24 school year, down from nearly 95% in 2019. Experts say the current increase in cases is largely affecting middle and high schoolers, whose immunity from vaccination as young children has waned.
The CDC recommends children receive a booster shot around 11 or 12 years of age.
4. Because they have smaller airways, babies and young children are typically at the highest risk for serious whooping cough complications, such as pneumonia. Children who have not had all their recommended vaccine doses are more likely to develop severe complications, according to the CDC.
