The US has seen nearly 28,000 whooping cough cases this year. Here’s what you need to know

(CNN) — For the second year in a row, the US has surpassed 25,000 whooping cough cases — another sign of the risks of falling vaccination levels.

Often called the “100-day cough,” whooping cough or pertussis begins with cold-like symptoms such as runny nose, fever or cough that can progress to coughing fits that last weeks or months, according to the US Centers for Disease Control and Prevention. A “whoop” sound when coughing may appear in the second phase of illness.

The infection can lead to severe illness or death, especially in young children: About 1 in 3 babies younger than 1 who have whooping cough requires care in a hospital. Still, experts believe that much of the disease goes unrecognized and unreported, the CDC says.

The CDC reported nearly 28,000 cases this year, an elevated level after a peak last year, when the agency reported 35,493 cases. One year earlier, in 2023, there were only 7,063 cases reported.

The last time numbers were similarly high was 2014, when there were 32,971 cases.

Thirteen deaths from pertussis have been reported in the US this year, according to the Pan American Health Organization, most of them children under 1 year old.

The rise in whooping cough is not unique to the US, according to the Pan American Health Organization, which serves as the World Health Organization’s office for the Americas region. Last year, 977,000 cases of pertussis were reported to WHO, a five-fold increase over 2023.

Dr. Scott Roberts, associate medical director for infection prevention at the Yale School of Medicine, believes the US rise is driven by falling vaccination rates along with a loss of population-wide immunity during the Covid-19 pandemic, among other factors.

“I worry vaccine hesitancy is playing a role. This is a vaccine-preventable illness, and any decline in vaccine rates will lead to increases in pertussis,” he said.

Vaccines prevent whooping cough

The CDC recommends routine diphtheria, tetanus and pertussis (DTaP) vaccination for all infants and children under 7 through a five-dose series beginning at 2 months of age. Children who get all five doses of the DTaP vaccine on schedule are 98% protected from illness within the year after the last dose. About 70% of children are fully protected five years after getting the last dose, according to the CDC.

Adults and adolescents are urged to get a booster Td or Tdap vaccination every 10 years, starting at the age of 11 or 12, to maintain protection. Roberts recommends choosing the version that protects against pertussis — Tdap — when possible.

“Last year, we had a lot of college outbreaks. What happens is, a lot of people get their childhood vaccine series, and then they don’t get the booster series,” Roberts said. He noted that many of those outbreaks were driven by students who had lost their immunity and were living in group settings where the disease spreads easily.

A return to shared indoor spaces after the pandemic may have also contributed to the increase, he said.

There had been limited exposure to routine pathogens because of Covid-19 mitigation measures, he said, but now “a greater proportion of people are getting exposed to the pathogen, all at the same time. I wonder if there is some degree of loss of population immunity that we’re still recovering from, and maybe things will [stabilize] over the next few years.”

Additionally, the PAHO epidemiological update highlights that vaccination coverage in the Americas region for the first and third doses of Tdap dropped to its lowest level in two decades during the Covid-19 pandemic. In 2021, coverage rates were at 87% for the first dose and 81% for the third dose of the vaccine.

Roberts emphasizes the importance of pertussis vaccines for children and pregnant women.

The CDC recommends a Tdap booster between weeks 27 and 36 of pregnancy, regardless of prior vaccination timing.

When a pregnant woman gets the vaccine, “the mom is going to develop antibodies [against pertussis],” Roberts said. These antibodies “spread through the placenta and get to the baby. When the baby’s born, they’ll have some immunity from that placenta.”

However, maternal antibodies “wane over a couple of months,” Roberts said, underscoring the need for children to complete the DTaP series.

Whooping cough symptoms and treatment

Whooping cough differs from flu, Covid-19 and the common cold in that it is caused by a bacterium rather than a virus, although early symptoms can look nearly identical, said Dr. Shira Doron, chief infection control officer for Tufts Medicine.

“Even though it can look like a viral respiratory infection, it’s actually a bacterial infection caused by the bacteria Bordetella pertussis, and it’s got some very characteristic features,” she said.

A week or two into the illness, some people may have a characteristic whoop when trying to catch their breath between heavy fits of coughing.

If coughing becomes severe, Doron said, patients may have what’s called post-tussive emesis: “vomiting when you cough or after you cough, and then the whooping sounds that also follow a coughing spell.” She advises people to see a doctor if they have severe worsening cough with symptoms such as vomiting or the whooping sound.

These severe symptoms result from airway damage caused by the bacterial toxin.

Antibiotics are the main treatment for whooping cough. When started early in the illness, Doron explained, medications can “break the chain of transmission” and lessen contagiousness, but they “do not change the course of the illness.”

Because pertussis rapid tests can be hard to find in clinics, Roberts said, health care providers often prescribe antibiotics based on symptoms.

“It’s pretty simple to do a five-day course of azithromycin – it’s called a Z-pak – that, in almost all cases, is just going to kill the pertussis right away,” he said. Given the cost and logistics of testing, “Most of the time, [doctors] will say, ‘let’s do the Z-pak and see how it goes.’ ”

Children and infants are especially at risk of severe illness, and certain symptoms should signal when whooping cough becomes an emergency.

Signs of shortness of breath, such as a child struggling to catch their breath or a baby’s skin turning blue, require immediate medical care. Infants are at higher risk of severe illness because their respiratory and immune systems are still developing, but severe cases are rare when children have been vaccinated, Roberts said.

States, counties urge residents to protect themselves

On Monday, health officials in South Carolina urged residents to ensure that they’re up-to-date on vaccinations amid a “concerning uptick” in cases of measles, whooping cough and chickenpox.

“The unfortunate increase in these diseases is linked to declining vaccination coverage in that region and, frankly, across the state,” Dr. Linda Bell, South Carolina’s state epidemiologist and Health Programs Branch director, said of the Upstate region’s large ongoing measles outbreak.

“This trend is both preventable and reversible,” Bell said in a news release. “Vaccines are one of the most effective tools we have for protecting our communities. When people choose not to vaccinate, outbreaks become more likely. Choosing not to vaccinate can not only put yourself at risk but also your neighbors, loved ones, and others in and beyond your community.”

Local health departments across the country have noticed declining vaccination rates. Dr. Raynard Washington, director of Mecklenburg County Public Health in North Carolina, said the county usually saw one or two whooping cough cases annually before numbers spiked to 68 in 2024. By October 2025, the county had recorded 48 cases this year.

“We’ve certainly seen an uptick here, particularly in younger children,” Washington said.

Many cases are among those not up to date on the five-dose childhood series, and there are often clusters in communities where families delay or decline vaccines. “It does put more people in those neighborhoods at risk,” he said.

Older adults are also a concern, he added, given their more vulnerable immune systems. He recommends that grandparents and other older adults “talk to their providers about anything they can do to protect themselves.”

Dr. Phil Huang, director and health authority of Dallas County Health and Human Services in Texas, said the county had 40 cases in 2023, 160 in 2024 and at least 195 this year.

According to data from the Texas Department of State Health Services, kindergarten vaccination rates against pertussis were estimated to have dropped from almost 94% in the 2023–24 school year to less than 90% in 2024–25 in Dallas.

Huang said the best thing parents can do is to ensure that their children are fully vaccinated. “That’s the best protection that we can do,” he said.

Roberts added that families should monitor local public health department websites for nearby cases, which may affect how doctors approach cold- or flu-like symptoms.

“If parents are concerned or the symptoms just aren’t going away after a couple weeks, you know that’s a time to come in and go see your doctor,” he said.

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