(The Center Square) – Whooping cough cases have been on the rise in Colorado over the past two years after a pandemic-era dip and a growing anti-vaccine movement.
Post-pandemic whooping cough cases rose to an average of 936 cases statewide between 2024-2025, passing the state’s pre-pandemic baseline for the vaccinated virus, according to preliminary state data.
“Evidence suggests this is due to a disruption in transmission of viruses and bacteria during the pandemic that led to a larger than usual pool of susceptible individuals, coupled with lower vaccination rates for some vaccine-preventable diseases,” Hope Shuler, a spokesperson with the Colorado Department of Public Health and Environment, told The Center Square, answering questions by email.
Whooping cough, also known as pertussis, can cause intense coughing for months and in rare cases cause death, usually among infants, according to the Mayo Clinic.
Cases of the illness have been on the rise since pandemic-era lockdown restrictions ended. Between 2015 and 2019, Colorado saw an average of 676 cases, which then fell sharply to 164 between 2020 and 2023.
But whooping cough cases have sharply rebounded since to an average of 936 cases from 2024 to 2025. The CDPHE noted that 2025 data is preliminary and could be subject to change.
Shuler told The Center Square that two-thirds of recent Colorado whooping cough cases have been from people under 18.
“These numbers are similar to numbers we had in Colorado prior to the pandemic, and we are monitoring case reports for other notable trends,” said Shuler. “Among 2025 cases, approximately 73% were up to date on pertussis-containing vaccines.”
Shuler also noted that whooping cough cases among vaccinated people is common as vaccine and booster immunity can wear off over time.
But concern among medical experts over the spread of whooping cough and other vaccinated illnesses has increased in recent years as vaccination rates have fallen.
“Measles, pertussis, influenza,” read an Association of American Medical Colleges article in 2025 by Patrick Boyle. “Not long ago, incidence of these and other childhood diseases had been dramatically reduced, thanks to vaccines — with measles virtually eradicated in the United States. Now, cases of measles and pertussis (whooping cough) are surging and childhood flu deaths have risen.”
U.S. Health and Human Services Secretary Robert F. Kennedy Jr. has long cast doubt on vaccines.
Earlier this year he drastically reduced and changed the national childhood immunization schedule, reducing the universally recommended 17 childhood vaccines to 11. The whooping cough vaccine remains universally recommended by medical professionals.
“Based on school and childcare data for 2024-2025, vaccination rates for DTaP and Tdap have decreased by 2.9% and 3.3%, respectively, since the 2019-2020 school year,” Shuler told The Center Square. DTap is the vaccine for infants and young children while Tdap is the vaccine for older children and adults.
Shuler added that post-pandemic disease spread has been seen beyond whooping cough in Colorado. “It is accurate to say this is the case more broadly, as we have seen an increase in other bacterial diseases, such as group A streptococcus and invasive pneumococcal disease, as well as in some vaccine-preventable diseases like measles.”
Despite the recent uptick, 2026 in Colorado has so far seen whooping cough spread more in-line with pre-pandemic levels at 278 cases.
