After a brief lull during the pandemic, whooping cough has bounced back, raising alarm among public health officials.

There have been more than 10,000 whooping cough cases in the United States so far this year, an unusually high number even by prepandemic standards, said Dr. Kathryn Edwards, a vaccine expert at Vanderbilt University who has studied whooping cough, also called pertussis, for decades. A branch of the World Health Organization recently called on countries with high levels of spread, including the United States, to bolster surveillance of the illness and increase vaccination efforts.

Edwards said the surge was most likely caused by a combination of falling childhood vaccination rates and a lack of exposure to the disease during the pandemic. That exposure “reminds” the immune system how to recognize and defend against the bacteria.

While less deadly than other vaccine-preventable illnesses like measles and polio, whooping cough — sometimes called the 100-day cough — is not a mild illness.

The respiratory illness is known for causing bouts of coughing so intense that they can lead to vomiting or even broken ribs. About a third of babies who get whooping cough need treatment at a hospital. Last year, 10 people died from the infection, and most of them were younger than 1 year old.

“These cough seizures can be so profound that you can lose consciousness and fall,” said Dr. William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center.

Who Should Get a Shot, and When?

The initial series of vaccines for pertussis — which also targets tetanus and diphtheria — is typically given during childhood. And doctors generally recommend booster shots for adults every 10 years.

This is because, while the current vaccine offers excellent short-term immunity against whooping cough, protection drops considerably after just a few years. (An earlier version of the shot offered much longer-lasting protection, but was phased out in 1996 because of side effects, like seizures and fevers.)

If you’re unsure about when you were last vaccinated, Schaffner said, there is no harm in getting an extra shot within the 10-year window, “other than a sore arm.”

Local public health officials may advise a booster shot for anyone living near an active outbreak. States on the West Coast — including Washington, Oregon and California — have reported the most cases this year, according to the latest data available from the Centers for Disease Control and Prevention.

And medical experts say there are other groups who may want to consider more frequent shots.

If You Have a Young Child in Your Life

Whooping cough, while unpleasant for adults, can be devastating for a child under 1 year old. Babies have a less developed immune system and, for reasons scientists do not fully understand, a much more severe reaction to the toxins released by the pertussis bacterium.

Of the five people who died from the infection this year, four were under 1 year old. Unvaccinated children are 13 times as likely to become infected as their fully vaccinated peers and more likely to suffer severe outcomes.

The bacteria are often spread to babies by adults who don’t realize their symptoms are from whooping cough, or who don’t have symptoms at all, Schaffner said.

If you’re planning to visit a child younger than 6 months old — and especially under 2 months old — experts recommend checking whether you’ve had a Tdap shot within the last five years. If not, or if you’re unsure, you should get a Tdap booster at least two weeks before interacting with the baby. This gives your body enough time to build up immunity.

If You Are Pregnant or a Preteen

Vaccination in the third trimester of pregnancy can offer strong protection for babies during the vulnerable early months of life, before they are able to get vaccinated.

Dr. James Cherry, a longtime pertussis researcher at the University of California, Los Angeles, said if all women were given the Tdap shot in their third trimester, as is recommended by the CDC, the country could eliminate “virtually all deaths” from whooping cough.

Yet only about 60% of pregnant women in the United States follow this recommendation.

As children get further away from their initial round of pertussis vaccines, they become increasingly vulnerable to a whooping cough infection. At 11 years old, most of the immunity from their childhood shots has worn off. At the same time, children are still spending most of their days in school, where the bacteria spread readily.

This year, more than a third of whooping cough cases have been among people 11 to 19 years old. For this reason, the CDC recommends that children get a booster shot at 11 or 12 years old.

While this age group is unlikely to have fatal complications, the cough often disrupts normal activities, like sleeping, eating and studying, and can linger for months after the initial infection.

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This article originally appeared in The New York Times.

By Teddy Rosenbluth/Matthew Ryan Williams
c. 2025 The New York Times Company