Whooping Cough (Pertussis) Is on the Rise: What to Know

Rates of pertussis, or whooping cough, a highly contagious respiratory disease, are increasing in the United States. As of early September, there were more than three times as many reported cases of pertussis compared to this time in 2023, according to preliminary data from the Centers for Disease Control and Prevention (CDC).

Although people of all ages can get pertussis, it is largely a disease that affects children and adolescents. Babies younger than one year old are at greatest risk of getting pertussis and developing severe complications. Of infants who develop whooping cough, roughly one-third need to be treated in the hospital.

There are several reasons why pertussis is on the rise, experts say. “Levels of pertussis dropped dramatically when we were all masking, and now this huge increase is getting us back to pre-pandemic levels, and probably a little above that,” says Thomas Murray, MD, PhD, a Yale Medicine pediatric infectious diseases specialist. “It’s a contagious respiratory virus that can spread fairly quickly through the population.”

While there is a vaccine for pertussis, babies don’t receive their first dose until they are two months old, which is why doctors suggest mothers get a booster of the vaccine during pregnancy, as it can offer some protection for the newborn. Furthermore, the vaccine’s effectiveness drops over time, Dr. Murray says. “You could still get the infection and potentially spread it, even if vaccinated. Plus, vaccination rates in general are lower since the pandemic,” he adds.

Additionally, when someone first becomes infected with pertussis, it can be difficult to differentiate it from the common cold, COVID-19, and respiratory syncytial virus (RSV).

“So there’s an opportunity to spread the infection before you know you have it,” Dr. Murray says, adding that the signature “whoop” sound (like a sharp gasp for air at the end of a hacking cough) doesn’t typically appear until a few weeks into the illness.

Like other respiratory viruses, pertussis spreads through coughing, sneezing, or breathing very close to someone. Sometimes, it can spread by touching a contaminated surface and then touching your nose, eyes, or mouth. Fortunately, pertussis can be treated with antibiotics.

Below, we talk more with Dr. Murray about whooping cough and common questions people may have.

Whooping cough is caused by a type of bacteria called Bordetella pertussis. The bacteria attach to tiny, hair-like extensions in the upper respiratory tract called cilia, which help clear mucus and other debris from the airway. When the bacteria release a toxin, it damages the cilia, and the airways swell.

When the cilia aren’t working as they should, the body reacts by coughing to clear the lungs. “The classic sign of pertussis is the cough, and that’s what will most often make a doctor test for it,” Dr. Murray says. “It has this specific sound, and you can cough so hard that it makes you vomit.”

[Click here to hear what whooping cough sounds like.]

The whooping cough, which can come in fits, may begin one to two weeks after the first symptoms appear. Early symptoms resemble the common cold and include a runny nose, low-grade fever, and a mild, occasional cough. Pertussis is most contagious during the early cold-like symptoms stage and for at least two weeks after the whooping cough begins. That cough typically worsens and becomes more frequent as the illness continues, and it can last from six to 10 weeks altogether.

For babies, however, many with pertussis don’t cough at all. Instead, they may have apnea (life-threatening pauses in breathing).

“Because they have a very narrow airway, it can actually cause them to stop breathing and they can get quite sick,” Dr. Murray says. “And unless the mother has been recently vaccinated during pregnancy, which we encourage, the baby has no pre-existing immunity. Those two things, in combination, can make a baby very, very sick.”

According to the CDC, in rare cases, whooping cough can be deadly for babies. Up to 20 babies have died each year since 2010 from whooping cough in the U.S.

Older children and adults can also develop complications, including pneumonia, but complications are usually less serious in these age groups, especially in those who have been vaccinated.

Still, for all ages, Dr. Murray says it’s important to contact your doctor if you notice a cough that sounds different. “If it’s episodes of a cough that are severe and difficult to stop, reach out to your health care provider,” he says. “You want to describe those symptoms, given that whooping cough is very contagious. The provider might want to see you at the end of the day or may want you in a separate waiting room, or to wear a mask, so you don’t spread it within the health care setting.”

Because early symptoms of whooping cough overlap with the common cold and other respiratory illnesses, a person with the illness might not visit the doctor right away or be tested. If your health care provider suspects pertussis (often at the point that a cough with a whoop begins), they can diagnose it with a polymerase chain reaction (PCR) test that requires taking a nasal swab. The sample is sent to a lab, and it might take a few days to receive results.

“If your doctor is highly suspicious of pertussis based on symptoms, it’s very reasonable to start treatment with antibiotics while you’re waiting for test results,” Dr. Murray says.

Whooping cough is treated with antibiotics, and starting them early can reduce the severity of infection, duration of illness, and risk of complications. Most often, oral antibiotics are given, and a course lasts five to 14 days. Furthermore, if one person in a family is diagnosed with pertussis, your doctor may suggest that everyone be treated with antibiotics as a precaution, since it spreads so easily, Dr. Murray says.

“One reason to treat is to stop the spread of transmission. The earlier you start treatment, the sooner you kill the bacteria and prevent it from spreading to others,” Dr. Murray says. “Often, however, by the time it's recognized, you're so far along in the disease that the treatment doesn't necessarily help make you feel better. But if you catch it really early, it might help.”

While the vaccines for pertussis are considered effective, immunity wanes over time, Dr. Murray says.

There are two types of vaccines. The DTaP vaccine is for babies (two months old) and children up to age 7. It protects against diphtheria, tetanus, and pertussis, and is given multiple times. The Tdap vaccine, which protects against the same illnesses but has a different dosage, is administered when a child is between ages 11 and 12.

Pregnant women are advised to get the Tdap vaccine between weeks 27 and 36 weeks for each pregnancy. The CDC advises that anyone 19 or older who has never received a dose of Tdap get one as soon as possible. After that, adults should get a Td (tetanus and diphtheria) or Tdap shot every 10 years, the CDC says. Given the choice, Dr. Murray recommends getting Tdap every 10 years as the pertussis protection can wane.

“Even though it’s traditionally thought of as a disease of childhood and adolescence—and certainly that's where it's more common—one of the reasons to stay up to date on your vaccines, especially if you're a grandparent, is that you can transmit it to babies,” Dr. Murray says. “The vaccine isn't just to protect yourself, but to protect individuals around you that might be at high risk for getting sick.”