(Nexstar) – Measles isn’t the only one making a fierce comeback in 2025.
Another disease that is particularly dangerous for young children, known as pertussis or pertussis cough, is spreading almost twice as fast as last year.
As of April 26, the most recent data available from the Centers for Disease Control and Prevention identified 9,047 cases among U.S. residents in 2025. That’s almost twice the number of cases last year, when around 4,700 cases were identified.
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Whooping cough tends to peak in spring and fall. It usually spreads through airborne respiratory drops when a person coughing, sneezing, or breathing with pertussis, breathing near another person. Symptoms are similar to those of a cold, but coughs become more and more severe with their unique sounds. This is the “hoop” when the person tries to ingest the air.
This disease is the most dangerous for babies too young to get the vaccine.
Experts say the outbreak of vaccine-preventable diseases, such as measles and pertussis, can indicate a change in attitude towards the vaccine. U.S. kindergarten vaccination rates fell last year, with the number of children with vaccine exemptions reaching an all-time high.
Where is Whooping Cough spreading quickly?
West Coast states have accounted for the largest share of lawsuits to date in 2025. Washington has reported more than 1,000 cases alone. According to the CDC, Oregon has 663 cases and California has 590 pertussis.
Another state cluster that reports a large number are Michigan (537), Ohio (494), Wisconsin (346) and Illinois (319).
Florida has at least 468 pertussis coughs in 2025.
Why does pertussis spread again?
One of the major theories of the recent rise in pertussis cases is the recent decline in vaccine uptake.
“Unfortunately, anti-vaccine sentiment is on the rise in the US,” said Dr. Erica Hayes, PhD, of Children’s Hospital of Philadelphia. “Our recovery isn’t as fast as we expected, and we needed it. And once again, if you go below 95% for vaccination, you lose the immune protection of that herd.”
The pertussis vaccine, which also protects against diphtheria and tetanus, is given in two, four, and six months. Pregnant women can get the vaccine to protect their newborns, but Hayes said enough women in the local area haven’t chosen them.
The CDC also recommends that adults get follow-up doses every 10 years.
The rise could also be linked to the type of vaccine being used, writes Annette Regan, a professor of epidemiology at UCLA. The old pertussis vaccine, which was used until the 1990s, was used to include the whole, B. Killed B. pertussis cells. However, Regan explains that these vaccines are more likely to cause fever or other side effects when administered by a baby.
As a result, we switched to a vaccine that contains some of the bacteria but entirely. These vaccine formulations are thought to have fewer side effects, Regan writes, but their protection may not last that long.
The Associated Press contributed to this report.
