Pertussis Snapshot
The Pertussis Snapshot provides quarterly pertussis surveillance data from 2020-2025 in California. The case counts shown are preliminary and may change after final review. Total counts for all figures and tables include cases for the entire year. Case counts for quarters 1 and 3 (Q 1-3) include cases reported with an onset date between January 1 and September 30. Total and Q 1-3 counts for the current year will be the same. Refer to "About the Data" for more details about the pertussis case data presented in the dashboard. Data highlights are provided with the dashboard, and you can download the data as an Excel workbook for your own analysis.
About the Data (PDF) | Download the Data (Excel)
Data Highlights
Between January 1 and September 30, 2025, 1,915 cases of pertussis have been reported in California, as compared to 1,917 reported during the same timeframe in 2024. In the first three quarters of 2025, pertussis cases in infants under four months of age increased by 54%, with 97 cases in 2025 compared to 63 cases in 2024. Pertussis activity was elevated in California's Northern and Central regions compared to last year. Statewide, 5% of 2025 cases were among infants under four months of age.