Throughout 2024, Marin County has been experiencing an outbreak of pertussis (aka whooping cough). Outbreaks are commonly occur every 3 to 5 years. As of September 30, 2024, Marin County Public Health (MCPH) has investigated 355 cases. The number of cases have been declining since September. In October and November, MCPH has investigated 14 pertussis cases.
Pertussis is a common, highly contagious bacterial disease. Most adolescents and adults recover without complications, but it can be deadly for infants. Within 3-5 days of antibiotic treatment, the disease is no longer transmissible to others.
Pertussis vaccines are effective, but not perfect. They offer good levels of protection during the first two years after getting the vaccine, but the protection decreases over time (“waning immunity.”) For this reason, we tend to see pertussis more in middle and high school age populations. Those who are vaccinated tend to have less severe disease.
Vaccination remains the best defense against pertussis, along with appropriate screening, treatment, and prophylaxis for high risk contacts. Anyone who is around an infant less than one year of age should have current pertussis vaccination.
Marin County Public Health recommends:
It is most critical for ill persons who are either high risk or may expose someone who is high risk to be evaluated by their health care provider. Persons considered at “high risk” of pertussis include infants (< 1 year old), pregnant women (especially in the third trimester), and anyone who spends time with infants or pregnant women. Health care providers may prescribe antibiotics to treat ill individuals or to prevent illness in healthy high risk household members who have been in contact with a person who is sick.
- Vaccinate infants, children, adolescents, and adults according to the ACIP schedule and implement cocooning around infants. Most importantly, pregnant women should receive the Tdap vaccine between 27-36 weeks of pregnancy to protect infants.
- Think pertussis. If other household members are or have been recently sick with a respiratory illness, particularly if with violent coughing fits and vomiting after coughing, discuss with your health care provider. People who have been vaccinated for pertussis often present with mild symptoms.
- Test for pertussis. People who have been vaccinated for pertussis often present with mild symptoms. Have a high index of suspicion and a low threshold for testing and evaluating individuals for pertussis. Testing is most critical for symptomatic persons who are either high risk or may expose someone who is high risk. Persons considered at “high risk” of pertussis include infants (< 1 year old), pregnant women (especially in the third trimester), and anyone who may expose infants or pregnant women.
- Treat pertussis cases with a course of appropriate antimicrobial therapy. The recommended antimicrobial agents for treatment or chemoprophylaxis of pertussis are azithromycin, clarithromycin, and erythromycin.
- Stop the spread. If you or your child is sick with pertussis, prevent spreading the illness to others by:
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Staying at home until at least 3 days of antibiotics are completed, or if the sick person did not receive antibiotics, stay at home until 21 days since the cough started.
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Coughing and sneezing into the elbow, not the hand. Use tissues and put used tissues in the waste basket.
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Wash hands frequently.
Please contact Marin County Public Health, Monday through Friday 8:30 a.m. through 5:00 p.m., if you have any questions or concerns.
P 415 473 4163
F 415 473 6002
MarinCD@marincounty.org
Marin County Public Health contacts cases to determine if there are high risk individuals who need chemoprophylaxis. High risk household contacts will be referred to their usual source of care for chemoprophylaxis.
Additional Information
Centers for Disease Control and Prevention (CDC). Pertussis (Whooping Cough)
California Department of Public Health (CDPH). Pertussis (Whooping Cough)