Whooping cough is staging an unwelcome comeback across Colorado after falling to pandemic-era lows, and parents and pediatricians say they are seeing the impact in schools and clinics. State health figures show a clear uptick in recent years, and public-health leaders warn that infants and school-aged children remain the most vulnerable. Officials point to slipping school vaccine coverage and the natural waning of immunity as likely culprits behind the rise.
State health officials told Denver7 that more than 930 whooping-cough (pertussis) cases were reported in Colorado in both 2024 and 2025, and that roughly two-thirds of infections involve people under 18. The department noted the 2025 counts were preliminary and could be revised. According to the station, officials said that 73% of 2025 cases had a record of vaccination, a pattern public-health experts link to protection that weakens over time, even after earlier doses.
Pediatricians Warn Parents
"We’ve seen quite a rise in pertussis cases in our community," said Dr. Stephanie Harris, a Lakewood pediatrician, who told Denver7 that many recent outbreaks have involved unvaccinated children. Clinicians report seeing more prolonged coughs and more testing for pertussis at clinics and emergency rooms as families bring in kids with persistent coughs that just will not quit. Doctors stress that while vaccination does not always prevent infection, vaccinated children typically have milder illness and a lower risk of severe outcomes.
Vaccine Gaps And Breakthrough Infections
Colorado's school and child-care immunization data and the state's immunization information system show declines in routine coverage since the pandemic, which local officials say leaves room for outbreaks. Per the Colorado Department of Public Health & Environment, kindergarten and teen immunization measures and CIIS records indicate lower DTaP and Tdap uptake compared with pre-pandemic years. State epidemiologists emphasize that because protection from both the childhood DTaP series and adolescent or adult Tdap boosters naturally wanes, breakthrough infections among vaccinated people are expected and can still sustain transmission.
National Context And Prevention
The Centers for Disease Control and Prevention's provisional 2025 surveillance report recorded 28,783 pertussis cases nationwide and lists Colorado with 1,141 cases that year, showing the state's rise fits a broader national pattern. The CDC notes infants under 1 year face the highest hospitalization risk and explains that waning vaccine-derived immunity means even up-to-date children can get pertussis, though the disease is often less severe in vaccinated people. To protect newborns and the most vulnerable, the agency recommends strategies such as ensuring pregnant people receive Tdap during each pregnancy (preferably at 27–36 weeks) and boosting school-entry vaccination coverage; the CDC pregnancy vaccination guidance outlines those recommendations in detail.
What Parents Should Do
Parents are urged to check their children's immunization records and call their pediatrician about missed DTaP doses or adolescent Tdap boosters. If someone in the household develops a persistent cough, ask the clinician about testing and the need for antibiotic treatment to protect infants and other high-risk household members. For local immunization data and resources, consult the Colorado Department of Public Health & Environment or your child's clinic to confirm vaccine status and discuss next steps.
