November Vax Corner: Pertussis on the Rise

The Vax Corner column is written by Maria Huang, MD, one of the co-chairs of the Vaccine Committee for the Washington Chapter of the American Academy of Pediatrics:

Whooping cough is spreading nationwide at the highest levels since 2014 with more than 19,000 cases¹ so far this year. This is four times as many compared to the same time last year. National DTaP vaccination coverage for kindergartners is steadily declining, translating to approximately 250,000 kindergarteners without full protection against pertussis.² During the 2023–24 school year, coverage declined to <93 percent for all reported vaccines, and the exemption rate increased to 3.3 percent from 3.0 percent the year before.² In mid-September 2024, a football championship subdivision game between Portland State and South Dakota was canceled because of a case of pertussis.³

Pertussis Key Points:

• Common cause of prolonged cough illness in adolescents and adults but rarely tested for.
• Highly contagious; incidence peaks in late summer or fall.
• Usually diagnosed by PCR, which has optimal sensitivity during the first three weeks of cough when bacterial DNA is still present in the nasopharynx. After the fourth week of cough, the amount of bacterial DNA rapidly diminishes, which increases the risk of obtaining falsely negative results.⁴
• Immunized adolescents and adults often test negative after two weeks from onset but symptoms may persist for 6-8 weeks and cough may continue for up to 10 weeks or more.
• When pertussis is strongly suspected, prophylaxis should be provided to the entire household and other close contacts at high risk without waiting for laboratory confirmation.⁵
• Persons with pertussis are infectious for 21 days after the onset of symptoms or until five days after the start of effective antimicrobial treatment.⁵

Consider the diagnosis of pertussis in the following situations, even in immunized patients:

• Persistent cough with no or low-grade fever that is paroxysmal, accompanied by gagging, post-tussive emesis, or inspiratory whoop in patients of any age.
• Any cough illness>two weeks duration with no alternative diagnosis in patients of any age.

Treatment

Follow CDC guidance⁶ for suspected or confirmed pertussis. Treatment should begin within the first one to two weeks of illness. Three macrolides (azithromycin, erythromycin, clarithromycin) are recommended for the treatment of pertussis. Azithromycin is most popular because of its simple five-day regimen and is the preferred choice for infants younger than one month of age.⁵

1. https://wonder.cdc.gov/nndss/static/2024/42/2024-42-table990.html
2. https://bit.ly/4fndC2h
3. https://www.msn.com/en-us/health/other/college-football-game-canceled-because-of-whooping-cough-outbreak/ar-AA1qAnPd
4. https://www.cdc.gov/pertussis/php/pcr-bestpractices/index.html
5. https://www.cdc.gov/surv-manual/php/table-of-contents/chapter-10-pertussis.html
6. https://www.cdc.gov/pertussis/hcp/clinical-care/index.html