Pertussis: A Brief Backgrounder for Primary Care
Cases of whooping cough in the US more than doubled in 2024, and 2 infants have died from the infection. Here is background on the infection and vaccine.
Pertussis, or whooping cough, is a highly contagious respiratory disease caused by Bordetella pertussis. As of early 2025, US cases have more than doubled compared to the same period in 2024, indicating a significant resurgence.
Pertussis was first described in Persia in the 15th century; in the 1930s, before vaccines were available, annual us cases exceeded 200,000. Vaccine introduction led to a 99% reduction in reported cases.
Pertussis progresses in 3 stages: • Catarrhal: Mild respiratory symptoms • Paroxysmal: Severe coughing fits with characteristic "whoop." • Convalescent: Gradual recovery over weeks to months.
Pertussis has an incubation period of approximately 7 to 10 days. An initial runny nose is followed by paroxysmal coughing, post-tussive vomiting and the characteristic inspiratory "whoop." Complications can be severe.
Pertussis exhibits cyclical outbreaks every 3–5 years. In 2025, cases have more than doubled compared to 2024, with >8,000 reported by March. In 2024, cases were 4x higher than in 2023. Increase is likely due to a combination of declining vaccination rates, waning adult immunity, and reduced public funding and outreach.
Poor vaccination against pertussis in children aged 6 months to 6 years presents a significant risk. Among children in that age range in 2024, 28.3% had unknown vaccination status, 35.6% were unvaccinated, and 38.3% had incomplete vaccination against pertussis.
Pertussis vaccine evolution: Whole-cell pertussis vaccine was introduced in the 1940s and replaced in the 1990s with an acellular formulation with fewer adverse events. The current aP vaccine is less robust than wP, and requires boosters every 10 years.
Pertussis diagnostic methods: Culture is gold standard with high specificity but lower sensitivity; PCR is rapid and sensitive; serology is useful in later stages to identify antibodies. Clinical criteria include persistent coughing for 2 weeks or more with paroxysms, an inspiratory whoop or post-tussive vomiting.
Pertussis treatment management overview: Antibiotics are first line with early administration potentially ameliorating; supportive care recommended for children including hospitalization; close monitoring required for complications, eg, apnea, dehydration.
Pertussis research, public health focus: Research has found genetic variations, which may impact vaccine efficacy; CDC has introduced enhanced surveillance to improve detection.
Whooping cough cases surpassed 6500 in March, putting the US on course for the most cases recorded since the first pertussis vaccine was developed in the late 1940s.1 More recent data from the Centers for Disease Control and Prevention put the count at more than 8000 cases, a greater than 2-fold increase over 2024.2 Before the vaccine's introduction, as many as 9000 children died of pertussis every year. Current estimates are that 20 infants die each year from the disease. Babies younger than 1 year are at the greatest risk for pertussis and approximately one-third require hospitalization.3
Experts point to several factors driving the current surge in cases4:
- Declining vaccination rates
- Vaccine hesitancy and misinformation impact on immunization
- Waning immunity
- Genetic mutation of the pathogen
Social distancing and other precautions taken during the COVID-19 pandemic also contributed to what is now a dangerous trend. "Levels of pertussis dropped dramatically when we were all masking, and now this huge increase is getting us back to pre-pandemic levels, and probably a little above that,” Thomas Murray, MD, PhD, a Yale Medicine pediatric infectious diseases specialist, said in a statement.3 Pertussis is recognized for its high level of contagion and is spread easily through the air.
The short slide show above offers a high-level review of the origins of the disease, the demographics, symptoms, and treatment. Pertussis vaccines have been in use for decades, are well studied, and significantly reduce the severity of illness and prevent hospitalizations and deaths. The CDC recommended vaccination and booster timing is available here.
