Pertussis Infection in Vaccinated Individuals

Introduction to Pertussis Immunity

Vaccinated individuals can still contract pertussis because immunity wanes 5-10 years after vaccination, making adolescents and adults susceptible despite childhood immunization, as noted by the Centers for Disease Control and Prevention 1, 2
The American Academy of Pediatrics and the Centers for Disease Control and Prevention acknowledge that pertussis vaccination provides significant but not complete protection, as immunity wanes over time after the most recent immunization 2
The increase in pertussis incidence has been particularly evident in adolescents and adults, with the greatest increase occurring in patients between the ages of 10 and 19 years, according to the Centers for Disease Control and Prevention 3
Immunity typically wanes 5-10 years after the last pertussis vaccine dose, as stated by the Centers for Disease Control and Prevention and supported by guidelines from the Advisory Committee on Immunization Practices 4, 1

The clinical presentation of pertussis in previously vaccinated individuals is often atypical and milder than in unvaccinated persons, with symptoms that may include persistent cough, as described by the American College of Chest Physicians 1, 2
Key differences in vaccinated individuals include the absence of the characteristic "whoop" and less severe symptoms, but still potentially transmissible, as noted by the Centers for Disease Control and Prevention 1, 2
Pertussis should be suspected when cough lasts ≥2 weeks with paroxysms, post-tussive vomiting, and/or inspiratory whooping, even in vaccinated individuals, according to diagnostic guidelines from the American Academy of Pediatrics and the Centers for Disease Control and Prevention 1
Diagnostic testing options include nasopharyngeal culture and PCR testing, with serologic testing potentially helpful in later stages of illness, as recommended by the Centers for Disease Control and Prevention 1

Current vaccination recommendations include DTaP primary series for children, Tdap booster for adolescents, and Tdap for adults, as recommended by the Advisory Committee on Immunization Practices and the Centers for Disease Control and Prevention 1
If pertussis is suspected or confirmed, macrolide antibiotics should be administered early in the course of illness, and isolation for 5 days from the start of treatment is recommended, according to treatment guidelines from the American College of Chest Physicians and the Centers for Disease Control and Prevention 1

Pertussis remains highly contagious, with one active case potentially infecting 70-100% of susceptible household contacts, as stated by the American College of Chest Physicians 2
The secondary attack rate exceeds 80% among susceptible persons, highlighting the importance of timely diagnosis and treatment to prevent transmission, as noted by the Centers for Disease Control and Prevention 5

The Centers for Disease Control and Prevention recommends that all household and other close contacts of persons with pertussis should receive antibiotic prophylaxis for 14 days, regardless of age and vaccination status 6, 7
Prophylaxis of all household members and close contacts may prevent or minimize transmission even though data from controlled clinical trials are limited 6, 7

For adults and children ≥2 weeks of age, a macrolide antibiotic is recommended as first-line prophylaxis, with options including erythromycin, azithromycin, and clarithromycin 8, 9
Erythromycin for 14 days is recommended at a dose of 1g/day for adults and 40-50 mg/kg/day for children 6, 7, 10
Azithromycin for 5-7 days is recommended at a dose of 500 mg on day 1, then 250 mg daily for 4 days for adults, and 10 mg/kg on day 1, then 5 mg/kg/day for 4 days for children 8, 9
Clarithromycin for 10-14 days is recommended at a dose of 500 mg twice daily for adults and 15-20 mg/kg/day in two divided doses for children 8, 9
For those with hypersensitivity or intolerance to macrolides, trimethoprim-sulfamethoxazole for 14 days is recommended at a dose of 320mg/1600mg per day for adults and 8mg/40mg/kg/day for children 6, 7, 8, 10

The Centers for Disease Control and Prevention recommends that all close contacts <7 years of age who have not completed the four-dose primary series should complete the series with minimal intervals 6, 7
Those who have completed a primary series but have not received a pertussis vaccine dose within 3 years of exposure should be given a booster dose 6, 7

Healthcare workers exposed to pertussis who remain asymptomatic can continue patient care while receiving chemoprophylaxis 8, 9