California declares whooping cough epidemic

California health officials said on June 4 that whooping cough, or pertussis, has reached epidemic levels in the state and warned that the disease poses the greatest danger to infants too young to be fully vaccinated. The California Department of Public Health urged clinicians and local agencies to report cases promptly and called on pregnant people, family members and caregivers of infants to make sure they are up to date on Tdap or DTaP vaccination. State guidance says pertussis is highly contagious and spreads through coughing, with severe coughing fits that can last for weeks or months. Infants can present differently from older children and adults, including by gagging, gasping or stopping breathing. ### Why are California officials using the word “epidemic”? California’s own surveillance pages show hundreds of cases already reported in 2026, even before the summer period that typically brings camps, travel and family gatherings. Between Jan. 1 and March 31, California recorded 471 pertussis cases, according to the state’s quarterly dashboard, which describes the counts as preliminary and subject to revision. (cdph.ca.gov) The Centers for Disease Control and Prevention says pertussis is cyclical and that state and local health departments generally have the most up-to-date information because national data can lag. CDC’s latest surveillance page says reported U.S. cases in 2026 are below the same period in 2025, but it also says whooping cough remains in circulation and can spread easily from person to person. ### Why are infants the focus of the warning? (cdph.ca.gov) California’s pertussis page says infants too young for vaccination are at greatest risk for life-threatening illness. The state’s quicksheet for health departments says babies under 1 year old — particularly very young infants — may not have the classic “whoop” and instead may have apnea, or pauses in breathing, along with color changes and respiratory distress. (cdc.gov) California officials have stressed that risk before. In a Jan. 3, 2025 news release, CDPH said the state had logged more than 2,000 cases between January and October 2024, including 62 hospitalized infants younger than 4 months and one infant death. State Public Health Officer Dr. Tomás J. Aragón said then that infants are “particularly vulnerable” and urged vaccination during pregnancy to pass protective antibodies to babies before birth. (cdph.ca.gov) ### What do the case numbers show so far this year? California’s first-quarter dashboard shows 22 of the 471 reported cases were in infants under 4 months old, or about 5% of the total. The same dashboard says 20 patients under age 18 were hospitalized, and 18 of those hospitalized children were unvaccinated. The state dashboard also says elevated pertussis activity has been reported in the South Bay Area, though the Bay Area region overall had not increased compared with the first quarter of 2025. (cdph.ca.gov) Because the figures are preliminary, the totals may change after final review. ### What does California want families and clinicians to do now? California recommends Tdap vaccination during every pregnancy, ideally between 27 and 36 weeks, because vaccination during pregnancy helps protect newborns before birth. (cdph.ca.gov) The state says babies should receive DTaP at 2, 4, 6 and 15 months, and again at 4 to 6 years, while preteens, teens and adults should stay current on Tdap. CDPH’s quicksheet says pertussis outbreaks are reportable in California, and the agency advises local health departments that outbreaks can be defined as three or more confirmed, epidemiologically linked cases outside the same household within 21 days. CDC says the latest national figures are available through the notifiable diseases system, but it directs readers to state and local departments for the most current counts. (cdph.ca.gov) ### Where will the next updates appear? California publishes pertussis surveillance on its quarterly dashboard and maintains a public pertussis information page with vaccine guidance and reporting resources. CDC also updates its pertussis surveillance page and says the National Notifiable Diseases Surveillance System carries weekly data, though state and local agencies may post faster updates. (cdph.ca.gov 1) (cdph.ca.gov 2)