WA state whooping cough cases surpasses 1,000. Is the surge slowing?

BELLINGHAM – Just four months into 2025, Washington had recorded more cases of pertussis, better known as whooping cough, than it had in all but three full years since 1960.

But as alarming as that number might seem, case rates have been on the decline for much of this year.

Last year, Washington had 26.06 cases of pertussis for every 100,000 people, according to the Centers for Disease Control and Prevention, the sixth-highest rate of any state.

Its 2,029 total cases were the most it’s seen since 2012, according to Washington State Department of Health data, when the state recorded nearly 5,000 cases of the illness.

You’d have to go back to 1950 to find a year when Washington saw over 2,000 whooping cough cases, and to 1962 to find a year the state broke the 20 cases per 100,000 residents threshold.

Last year’s surge peaked in mid-November, according to DOH data, so even as the pertussis rate has declined, high case counts carried into the early months of this year.

Over the first week of this year, Washington recorded over 100 cases of whooping cough, but that number dropped steadily until it dipped below 40 in the eighth week of the year.

The weekly case count rebounded slightly, holding steady right around 60 for over a month.

Early estimates indicate that the case rate has begun to fall again, but those estimates could rise as health officials investigate potential cases.

But even as pertussis rates decline, the total case count on the year is one of the highest Washington has seen in decades.

Through April 26, DOH had recorded 1,028 cases of whooping cough in Washington this year, over five times the state’s case count at the same point last year.

This year was only the fifth time since 1960 that the state has recorded over 1,000 cases.

Pertussis rates typically peak around the summer and fall, according to the American Lung Association, case counts could continue to climb.

A sharp spike in case totals doesn’t always mean more people are getting sick.

According to the CDC, case counts have risen since the COVID-19 pandemic largely due to better and more accessible testing.

At the onset of last year’s pertussis surge, Eric Chow, chief of communicable disease epidemiology and immunization at Seattle and King County’s health department, told McClatchy that those factors were contributing to Washington’s high case counts.

“As people return to normal activities, as people are traveling more, we’re seeing an increase in these types of respiratory diseases … We’re having better PCR tests, or the molecular tests, that have been rolled into these other comprehensive respiratory panels that have come about more commonly as a result of the pandemic,” Chow said.

DOH’s school immunization data dashboard also indicates that vaccination rates against pertussis could be down.

In the state’s three biggest counties, King, Pierce and Spokane, the pertussis vaccination rate among kindergaten students stood at 94.5%, 93.1% and 90.1%, respectively, for the 2019-2020 school year.

In the 2023-24 school year, those numbers stood at 91.1%, 90.2% and 85.1%.

The vaccine against whooping cough is widely available.

It’s commonly given as part of the tetanus shot, so you could be protected against pertussis without knowing it.

The DTaP and Tdap vaccines both protect against tetanus, diphtheria and pertussis, with DTaP approved for children under the age of 7 and Tdap approved for anyone older.

You can check your vaccine record at MyIRMobile or by contacting your health care provider, school or DOH.

According to the CDC, the vaccine is around 98% effective against pertussis for children during the first year after the final dose, and 71% effective in the five years following the last dose.

In adults, it’s 73% effective in the first year after a shot but wanes to 34% protection four years later.

Getting the vaccine during pregnancy can also significantly reduce the risk that the infant will contract pertussis, according to the CDC.

According to the CDC, pertussis typically looks like a common cold at first, but is characterized by a violent cough that develops after a week or two.

The cough typically lasts between one and six weeks.

It’s most dangerous in infants and young children, with one-third of children under the age of 1 who contract whooping cough needing hospitalization.

The death rate for infants who contract the disease is around 2%, according to an entry on the disease in the National Library of Medicine, but deaths are rare for anyone else.

Slightly more than 70% of cases occur in children 5 years old or younger, according to the entry.