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New year-end data from the Centers for Disease Control and Prevention (CDC) show cases of pertussis – commonly known as whooping cough – in the state of Washington.

The surge far outpaced the national trend, which still saw a year-over-year increase of 401%.

By Dec. 28, corresponding data from the state shows Washington saw 2,040 cases of whooping cough in 2024 – the fifth most cases among any state in the nation. In 2023, the state recorded 87. (A PDF of the state’s report can be viewed .)

Clark, Spokane and King Counties recorded the most cases, but prevalence was highest in Whitman and Chelan Counties, where the rate of illness reached about 169 and 180 people of every 100,000, respectively. The disease was spotted within at least 33 of Washington’s 39 counties.

State health officials previously warned the public, telling Washingtonians in a Nov. 7 press release it was “closely monitoring the situation,” while federal health officials explained the increase as a “return to more typical trends” after the COVID-19 pandemic.

Previous coverage: Washington hit with steep hike in whooping cough cases

No official cause revealed, but vaccines are urged

No direct cause was specified in the state’s release, but officials urged the public to renew their vaccinations.

“The surge in pertussis cases is a stark reminder of how critical vaccinations are in protecting our most vulnerable, especially infants for whom it can be life threatening,” said Dr. Tao Sheng Kwan-Gett, chief science officer at the Washington State Department of Health. “To protect babies from whooping cough, people of all ages should get up to date on pertussis vaccination, and anyone with symptoms should see a health care provider to see if testing and antibiotic treatment are needed.”

Nationally, the U.S. recorded 35,435 cases in 2024 – its highest amount since 2012.

While it’s a significant increase from the country’s 2023 total of 7,063 cases, officials likened last year’s spread to those of pre-pandemic levels, which were normally more than 10,000 cases per year.

A piece on the CDC website cited the pandemic specifically as to why numbers dropped in recent years ahead of 2024.

“It’s likely mitigation measures used during the pandemic (e.g., masking, remote learning) lowered transmission of pertussis,” .

Sam Campbell is a reporter, editor and anchor at ³ÉÈËXÕ¾ Newsradio. You can read more of Sam’s stories here. Follow Sam on , or email him here.