Whooping Cough Prophylaxis
Vaccination Strategy
All adolescents and adults should receive a single dose of Tdap vaccine to replace their next scheduled Td booster, with priority given to those who have or anticipate close contact with infants under 12 months of age. 1
Routine Adolescent and Adult Vaccination
Adolescents and adults aged 11–64 years should receive one dose of Tdap, even if their last Td was given less than 10 years ago, particularly when there is increased risk of pertussis exposure or contact with high-risk individuals. 1
The interval between Td and Tdap can be as short as 2 years; shorter intervals may be used when protecting against pertussis outweighs the risk of local reactions. 1
Healthcare personnel in hospitals or ambulatory care settings with direct patient contact should receive Tdap as soon as feasible, with priority for those caring for infants under 12 months. 1
Pregnancy and Postpartum Vaccination
Every pregnant woman should receive Tdap between 27 and 36 weeks' gestation with each pregnancy to provide passive immunity to the newborn, regardless of prior Tdap vaccination history. 2, 3
Women of childbearing age who might become pregnant should receive Tdap before conception when possible, since approximately half of U.S. pregnancies are unplanned. 1
If Tdap was not given during pregnancy, it should be administered immediately postpartum before hospital discharge; breastfeeding is not a contraindication. 1
Protecting Infants Through Contact Vaccination
Parents, grandparents under 65 years, childcare providers, and all adults with close contact to infants under 12 months should receive Tdap at least 2 weeks before beginning contact with the infant. 1
"Cocooning" (vaccinating only close contacts) is no longer the primary strategy because vaccinated individuals can still contract and transmit pertussis; maternal vaccination during pregnancy is now the cornerstone of infant protection. 2, 3
Antibiotic Chemoprophylaxis (Post-Exposure Prophylaxis)
All household and close contacts of a pertussis case should receive macrolide antibiotic prophylaxis within 21 days of exposure, regardless of age or vaccination status, with azithromycin as the preferred agent. 1, 4
Who Requires Prophylaxis
Priority groups for post-exposure prophylaxis include: all household members, infants under 12 months (especially under 4 months), pregnant women in the third trimester, and healthcare workers with known exposure. 1, 4
The decision to provide prophylaxis weighs the infectiousness of the index case, intensity of exposure, potential for severe disease in the contact, and risk of secondary transmission to high-risk individuals. 1, 4
Pertussis has a secondary attack rate exceeding 80% among susceptible household contacts, making prophylaxis essential even for vaccinated individuals who can still contract and transmit the disease. 4, 5
Recommended Antibiotic Regimens
Azithromycin is the first-line agent for prophylaxis in all age groups due to superior tolerability, shorter treatment duration, and better compliance. 1, 6, 4
Age-Specific Azithromycin Dosing for Prophylaxis:
Infants 1–5 months (alternative): 10 mg/kg on day 1, then 5 mg/kg daily for days 2–5 1, 6
Children 6 months and older: 10 mg/kg (maximum 500 mg) on day 1, then 5 mg/kg (maximum 250 mg) daily for days 2–5 1, 6
Adults: 500 mg on day 1, then 250 mg daily for days 2–5 1, 4
Alternative Agents:
Clarithromycin: 7.5 mg/kg (maximum 500 mg) twice daily for 7 days in children; 500 mg twice daily for 7 days in adults 1, 4
Trimethoprim-sulfamethoxazole (TMP-SMZ): Acceptable alternative for patients over 2 months when macrolides are contraindicated 1, 6
Special Populations
For infants under 1 month, azithromycin is strongly preferred over erythromycin because erythromycin carries a markedly higher risk of infantile hypertrophic pyloric stenosis (IHPS). 1, 6
Infants under 1 month receiving any macrolide must be monitored closely for IHPS and other serious adverse events. 1, 6
Pregnant women receive the same antibiotic regimens as non-pregnant adults; macrolides are safe during pregnancy. 4
For infants 1–5 months, azithromycin or clarithromycin are first-line agents based on demonstrated in-vitro activity and safety profiles, despite lack of FDA licensure for this age group—the benefit of preventing severe disease outweighs medication risks. 1, 6
Timing and Effectiveness
Prophylaxis must be initiated within 21 days of exposure to be effective; administration during the first 21 days after the index case's cough onset can prevent symptomatic infection in contacts. 1, 4
The goal of prophylaxis is eradication of Bordetella pertussis from the nasopharynx of both symptomatic and asymptomatic carriers to prevent secondary transmission. 6, 4
Asymptomatic contacts who receive prophylaxis may continue normal activities including work; routine laboratory testing is not required—clinical monitoring suffices. 4
Infection Control Measures
Confirmed or suspected pertussis patients should maintain respiratory isolation for 5 days after starting appropriate antibiotics; if antibiotics cannot be given, isolation must continue for 21 days from cough onset. 6, 5
In healthcare facilities, place pertussis patients in private rooms or cohort with other pertussis cases, and healthcare workers should wear surgical masks when within 3 feet of the patient. 6, 4
Healthcare workers who cannot receive prophylaxis should be excluded from caring for children under 4 years for 7–14 days post-exposure if mandated by state law. 4
Common Pitfalls and Caveats
Do not withhold prophylaxis based on vaccination status—vaccine immunity wanes after 5–10 years, and vaccinated individuals can contract and transmit pertussis. 6, 5, 2
Do not delay prophylaxis while awaiting laboratory confirmation—the 21-day window is critical, and secondary attack rates are extremely high. 4
Avoid erythromycin in infants under 6 months due to the strong association with IHPS; azithromycin presents substantially lower risk. 1, 6
Remember that antibiotic prophylaxis provides only short-term protection against transmission—it does not confer lasting immunity, which requires vaccination. 4, 5
Neither vaccination nor natural infection provides lifelong immunity; protection wanes over time, making booster vaccination and prompt prophylaxis essential strategies. 6, 5, 3
Erythromycin and clarithromycin inhibit the cytochrome P450 enzyme system and can interact with other medications; azithromycin does not have this interaction, making it safer in patients on multiple medications. 1