From the Guidelines
Yes, pertussis (whooping cough) can occur despite vaccination with DTaP (diphtheria, tetanus, and pertussis) vaccine. While the pertussis vaccine significantly reduces the risk of infection, it does not provide 100% protection. Vaccinated individuals can still contract pertussis, though they typically experience milder symptoms and shorter illness duration than unvaccinated people. This occurs because vaccine-induced immunity wanes over time, with protection decreasing 5-10 years after the last pertussis vaccine dose 1.
Key Points to Consider
- Neither vaccination nor natural disease confers complete or lifelong protective immunity against pertussis or reinfection 1.
- Older children, adolescents, and adults can become susceptible to pertussis after a complete course of vaccination during childhood 1.
- The Advisory Committee on Immunization Practices (ACIP) recommends 5 doses of diphtheria and tetanus toxoid and acellular pertussis (DTaP) vaccine at ages 2,4,6,15--18 months, and 4--6 years 1.
Implications for Clinical Practice
- Booster doses, such as the Tdap vaccine, are crucial for maintaining protection against pertussis, particularly in adolescents and adults.
- Early diagnosis and treatment with antibiotics, such as azithromycin, can reduce symptom severity and prevent transmission to others, even in vaccinated individuals who develop the infection.
- It is essential to consider the waning immunity and the potential for pertussis infection in vaccinated individuals when assessing patients with respiratory symptoms.
From the Research
Pertussis Despite Vaccination
- Pertussis, or whooping cough, can still occur despite vaccination with the DTaP (diphtheria, tetanus, and pertussis) vaccine 2, 3, 4, 5, 6.
- The vaccine does not confer long-term immunity to clinical infection, and evidence of pertussis infection has been reported in vaccinated individuals 3.
- Vaccinated individuals can still contract and transmit pertussis, highlighting the importance of continued vigilance and monitoring 4.
Vaccine Effectiveness
- The effectiveness of the pertussis vaccine in preventing disease can wane over time, leading to changes in immunization recommendations 3, 4.
- Maternal vaccination with Tdap has been shown to be effective in preventing pertussis disease in infants under 3 months of age, with estimates of effectiveness ranging from 69% to 93% 5.
- Vaccination strategies, including cocooning and maternal immunization, have been implemented to reduce the burden of pertussis disease in high-risk populations 5, 6.
Disease Burden
- Pertussis disease incidence rates in infants under 6 months of age are substantial, exceeding 1000 cases per 100,000 population during outbreaks 5.
- The disease burden is highest in infants too young to be fully immunized, with virtually all pertussis deaths occurring in this age group 5.
- Limited data suggest that incidence rates of pertussis disease have declined in infants after the introduction of Tdap maternal immunization programs 5.