Full Breakdown
Colorado Sees Surge in Whooping Cough Cases After Pandemic-Era Lows
6/1/2026, 9:02:53 PM
Rising Pertussis Cases in Colorado
The Colorado Department of Public Health & Environment (CDPHE) reported more than 930 pertussis cases in both 2024 and the preliminary 2025 count, reversing a decline that persisted through the pandemic. Approximately two-thirds of the cases involve individuals younger than 18.
Post-Pandemic Vaccination Decline
School-age coverage for the DTaP series fell 2.9% and for the Tdap booster fell 3.3% in the 2024-2025 school year vs. the 2019-2020 baseline. CDPHE officials attribute part of the resurgence to waning immunity as protection from childhood and adolescent vaccines diminishes over time.
Data Snapshot
- Reported cases: >930 in 2024; >930 (preliminary) in 2025.
- Age distribution: ~66% under 18.
- Vaccination status: 73% of 2025 cases occurred in individuals with at least one pertussis vaccine.
- Historical trend: Local case counts have risen more than 600% since 2006.
Official Health Agency Statements
CDPHE emphasized that breakthrough infections can happen because immunity from DTaP and Tdap wanes, and that children missing booster doses face higher infection risk. Pediatrician Dr. Stephanie Harris of Kids First Pediatrics reiterated that vaccination remains the most effective preventive tool and that vaccinated children experience milder illness.
Community Concerns
Derick Vranizan, a Denver parent of two school-age children, voiced worry about the disease’s impact on young children and stressed reliance on pediatric guidance. He noted that close contact in classrooms or workplaces can facilitate rapid spread.
On-the-Ground Observations
Dr. Harris reported that many recent outbreaks involve unvaccinated children, while also noting many cases among previously vaccinated individuals, underscoring the role of waning immunity.
Conflicting Reports & Gaps
The 2025 case count remains preliminary and may be revised. Although 73% of reported cases were in vaccinated individuals, Dr. Harris noted that the majority of children in recent outbreaks were unvaccinated, causing tension between breakthrough and vaccine-coverage narratives.
Implications
The resurgence raises concerns for schools and childcare settings, where pertussis can spread quickly. Declining vaccination rates combined with waning immunity increase the likelihood of community transmission and prompting booster uptake.
Next Steps
CDPHE indicated ongoing monitoring of trends and urged families to ensure timely booster vaccinations, especially for adolescents and adults lacking a pertussis vaccine in the past decade.
Verbatim Quotes
- “We’ve seen quite a rise in pertussis cases in our community,” — Dr. Stephanie Harris, Kids First Pediatrics
- “In most of these outbreaks that we have seen lately, the majority of the children have been unvaccinated,” — Dr. Stephanie Harris
- “Breakthrough cases can occur in fully vaccinated individuals because immunity from both childhood vaccines (DTaP vaccine series) and adolescent/adult boosters (Tdap) naturally wanes over time,” — CDPHE spokesperson
- “Vaccination really is the best prevention,” — Dr. Stephanie Harris
