Editor’s note: This story is an update of an article originally published on August 20.

Whooping cough — a highly transmissible infection of the lungs and airways that mostly affects babies and young children — is on the rise in the United States.

Also called pertussis, the condition gets its name from a distinctive high-pitched intake of air that commonly follows a severe coughing fit. An audio recording posted by the U.S. Food and Drug Administration (FDA) illustrates just how miserable the cough can be.[1]

Over the past few years, during and since the COVID-19 pandemic, the number of people experiencing whooping cough has been lower than usual. Recently, however, the Centers for Disease Control and Prevention (CDC) reported that cases as of October 5 had jumped to more than four times that recorded by this same period in 2023 — nearly 17,600 versus about 4,000.[2]

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“We’re now beginning to return to pre-pandemic levels, where we typically see more than 10,000 cases of people with whooping cough each year,” wrote the CDC in a press release.[4]

Why Is Whooping Cough Coming Back?

Stephen Aronoff, MD, a professor of pediatrics who specializes in infectious diseases at the Lewis Katz School of Medicine at Temple University in Philadelphia, suggests that the increase in infections, at least in part, is due to people coming out of isolation, not masking, and dropping social distancing and vigorous respiratory-hygiene practices that were common during the peak years of coronavirus spread.

“We certainly saw traditional respiratory viruses in kids basically disappear in 2021 and 2022, and it wasn’t until everything got back to normal that we started to see resurgences of those viruses,” he says.

Routine vaccination rates also dropped during the pandemic and have yet to rebound. The National Council of State Legislatures reported earlier this year that kindergarten vaccine coverage decreased during both the 2020–21 and 2021–22 school years after holding steady for a decade. The vaccination rate did not return to pre-pandemic levels during the 2022–23 school year.[5]

Other factors likely contribute to the swelling case count, such as improvements in the diagnosis and reporting of the illness.

Since the protection provided by whooping cough vaccination decreases over time, the CDC expects to see whooping cough cases rise in both unvaccinated and vaccinated people.[4]

Vaccination Provides the Best Protection Against Whooping Cough

Despite the waning power of vaccination, Alex Sette, a doctor of biological sciences and a professor at the La Jolla Institute for Immunology in California, underscores that these shots continue to offer the best defense against whooping cough.

Before the availability of a pertussis vaccine in the 1940s, more than 200,000 cases of whooping cough were recorded annually, and the disease was a major cause of death among U.S. children.[6]

“There is a lot of concern in the medical scientific community about misinformation and the whole polarization associated with vaccine acceptance,” says Dr. Sette. “People may not be as diligent in providing childhood vaccination to their children, which is very concerning because if more people are not properly vaccinated, that is potentially a leading factor in the increased circulation of pertussis.”

The CDC stresses that vaccination is the best way to protect against pertussis and its complications. DTaP (diphtheria, tetanus, pertussis) vaccination is recommended at 2, 4, and 6 months; at 15 through 18 months; and at 4 through 6 years.

Tdap (which contains a lower-dose vaccine of the pertussis vaccine to boost immunity) is recommended for older children and adults.[7]

To best protect newborns against whooping cough, the CDC urges pregnant people to get the Tdap vaccination during their third trimester.[8]

“By vaccinating the pregnant mother-to-be, you boost her level of antibodies and that passes on and protects the child in the first few months when it’s most vulnerable,” says Sette.

Whooping Cough Is a Potentially Life-Threatening Illness

Whooping cough is caused by Bordetella pertussis bacteria, which attach to the cilia (tiny, hair-like extensions) that line part of the upper respiratory system, then release toxins that damage the airways, causing them to swell.

At first, it can be hard to tell if someone has whooping cough, because early symptoms can look like the common cold. During the first one to two weeks, the infected person may just have a runny or stuffed up nose, an occasional cough, and possibly a low-grade fever.[9]

After the initial symptoms fade, the illness can take a dramatic turn for the worse. At that point, an infected person typically has severe coughing fits as their body tries to clear mucus from the airways.

In bad cases, people experience spells of harsh and constant coughing. The “whooping” sound comes from a sudden inhalation as they fight to catch their breath. These coughs can sometimes last as long as three months.

“One of my professors used to refer to pertussis as the cough of 1,000 days, because people can have these prolonged, chronic coughs,” says Dr. Aronoff.

Babies especially may struggle to breathe or have life-threatening pauses in their breathing. About 1 in 3 infected babies younger than 1 year old who get whooping cough need care in the hospital.

Sometimes, the coughing can be so severe that the afflicted person may vomit or even fracture a rib.

Antibiotics can kill the infection, and by identifying the illness early on through medical tests, treatment can begin to reduce the chances of extreme illness.

Because the bacteria that cause whooping cough spread easily via small respiratory droplets, and because babies are most vulnerable, Aronoff urges adults who are sneezing or coughing to be extra cautious around younger children.

“Historically, pertussis has not been such a problem in adults as it is in unimmunized younger infants,” he says. “Older individuals, however, can acquire the bacteria and then unknowingly spread it to younger kids. Grandpa may have a nasty cough and not think twice about it when he’s holding his 2-month-old grandchild, but then the grandchild gets infected.”

As whooping cough cases continue to trend upward, Aronoff encourages everyone to keep up with their vaccinations.

“Vaccines work, and the data show that when we don’t vaccinate, we have outbreaks,” he says.

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