Rates of pertussis, also known as whooping cough, are surging in Texas, Florida, California, Oregon, and other states and localities across the country.
The outbreaks are fueled by falling vaccination rates, fading immunity, and delays in public health tracking systems, according to interviews with state and federal health officials. Babies too young to be fully vaccinated are most at risk.
“Pertussis cases increase in a cyclical fashion driven by waning immunity, but the size of the outbreak and the potential for severe outcomes in children who cannot be vaccinated can be mitigated by high coverage and good communication to folks at risk,” said Dr. Demetre Daskalakis, a former head of the Centers for Disease Control and Prevention’s immunization program, who resigned in August.
Before the first pertussis vaccine became available in the early 1900s, whooping cough was one of the most common childhood diseases and a major cause of childhood death in the United States. Today, children get a series of DTaP shots (full-dose version) starting at 2 months old, and teens and adults receive a Tdap booster (lower-dose version) every 10 years. (Both vaccines target diphtheria and tetanus in addition to pertussis.)
Until recently, 8 in 10 toddlers had received four doses of the DTaP vaccine by age 2, and case rates were controlled. But vaccine coverage has declined since the COVID pandemic and increases in state nonmedical exemptions have widened immunity gaps, which is when the proportion of individuals who are immune falls below the level needed to contain spread.
Texas logged 1,928 pertussis cases in 2024. By October 2025, the state had exceeded 3,500. National numbers are just as stark: In the first three months of 2025, the U.S. tallied 6,600 cases — four times last year’s pace and 25 times 2023’s. Several states are posting their highest case totals in a decade, and outbreaks from Louisiana to South Dakota to Idaho make clear this surge isn’t regional. It’s everywhere.
Key factors behind these numbers
Texas lawmakers recently passed a law that made it easier for parents to claim nonmedical exemptions from school vaccine requirements by allowing them to download exemption forms online. These forms now go straight to schools, not health departments, making the exemptions harder to track.
Dallas County Health and Human Services Director Dr. Phil Huang said the full impact of the new exemption rule is not yet known because it began this school year, but he expects it will make school-level vaccination rates fall even more.
He’s already noted a dramatic drop in vaccinations. Normally, during back-to-school season, “our whole front downstairs area is packed,” he said. “We did not see that this year.”
Dr. Huang believes fear of immigration enforcement may be keeping at least some families, especially Hispanic families, from getting vaccinated. Dallas County is about 40% Hispanic. “We think that a lot of them are deterred by the ICE activity,” he said, referring to Immigration and Customs Enforcement.
More complications: These vaccines protect against severe disease, but protection against infection fades over time, as is the case with the COVID and influenza vaccines.
The U.S. switched in the 1990s from whole-cell pertussis vaccines to “acellular” ones, which cause fewer side effects but do not last as long. Because more adults today than in the past received the acellular vaccine as children, many have lost immunity over time and may unknowingly pass the infection to babies.
Babies face the greatest risk
Whooping cough is especially dangerous for infants under a year old. Some stop breathing during coughing fits. Many need hospital care, about 1 in 5 of whom develop pneumonia, and about 1% of whom die.
Because of this high risk, the CDC urges pregnant women to get a Tdap vaccine during every pregnancy. This allows the mother’s antibodies to pass to the baby before birth.
Health officials once promoted “cocooning,” vaccinating all family members and caregivers around the baby, but that strategy was hard to carry out in real life and is no longer widely recommended. Vaccination of pregnant women and babies at 2 months of age remains the strongest protection.
Better testing finds more cases
Modern PCR testing is also uncovering more pertussis cases than in the past. Many clinics now routinely use this lab-based technology to test for several respiratory infections at once, including pertussis. Ten years ago, these panels were uncommon.
CDC experts say this explains part of the rise in case counts. But the large number of infant hospitalizations and the size of state outbreaks show that true transmission has also increased.
A growing worry: antibiotic resistance
Doctors normally treat pertussis with macrolide antibiotics, such as erythromycin, azithromycin, and clarithromycin. These drugs work best early in the illness and help stop spread. Another drug, trimethoprim-sulfamethoxazole, is an option for some older infants and adults.
But macrolide-resistant pertussis has become common abroad, especially in China, and recent reports show resistance rising in Peru. In the U.S., resistant cases have been rare.
CDC officials warn that resistant strains could spread more easily through international travel. Because treatment options are limited, especially for very young infants, health workers are watching this closely.
Dr. Huang said macrolide resistance has not been seen yet in Dallas County. But he is aware of the national concern.
What happens now
The resurgence of whooping cough has no single cause. Instead, several problems are occurring at once: falling vaccine coverage, only about 60% of pregnant women receiving Tdap, waning immunity, improved testing, and early signs of antibiotic resistance.
Health experts say solutions must match the problem’s complexity.
Across the nation, clinicians are being told to have a higher suspicion for pertussis when they see patients, especially children or caregivers of newborns with a persistent cough or coughing fits followed by vomiting. Babies who stop breathing or turn blue need immediate care.
Obstetricians are encouraged to discuss Tdap during every pregnancy. Pediatricians and family doctors are urged to check booster status for teens and adults.
Several states have issued health advisories over the past two years, including Texas, which has issued alerts in both 2024 and 2025 urging clinicians to stay vigilant.
Dr. Huang said Dallas County is trying to rebuild public health outreach programs that were cut when COVID funding ended. But staffing is still limited. “There’s just a lot of different things that are making it more difficult,” he said.
He also noted that Dallas County now receives immunization registry data only once a month, rather than daily, making it harder to track vaccine coverage. “We don’t have that yet. … It’s not real time,” he said.
Protecting the youngest
As the holiday season approaches, experts urge families with newborns to take extra care:
- Ensure infants and children are up to date with their childhood vaccines and that everyone in the family is up to date with their vaccines for influenza, COVID, and RSV, or respiratory syncytial virus.
- Keep sick visitors away.
- Seek care quickly if an infant has a cough or pauses breathing.
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