On Dec. 10, 2025, Oregon has reported more cases of whooping cough this year than at any time in state history, and health officials say falling vaccination rates — especially among pregnant people — are adding to the danger for infants.

As of Tuesday, the Oregon Health Authority has logged 1,475 cases of pertussis, commonly known as whooping cough. That surpasses the previous annual record of 1,420 cases set in 1950. The rise in Oregon and elsewhere is being fueled in part by declining vaccination rates, especially among pregnant people in rural areas, they said.

Pertussis is a highly contagious bacterial infection that spreads through coughs and sneezes. While people of all ages can become sick, infants have much smaller air passages and are far more likely to suffer severe illness, land in the hospital or die. So far this year, Oregon has recorded 87 cases in infants younger than 12 months. Officials said 22 of those babies were hospitalized, and one infant died — the state’s only pertussis-related death in 2025.

Since babies can’t be vaccinated until they reach 2 months, protection in the first months of life comes from antibodies inherited in the womb. To help protect babies, medical groups like the American Academy of Pediatrics recommend that pregnant people get the whooping cough vaccine known as Tdap — which also helps prevent tetanus and diphtheria — between weeks 27 and 36.

New state data shows only 69% of pregnant people in Oregon received a Tdap shot last year — down from 72% in 2020. Vaccination rates in 2024 varied widely by county, ranging from as low as 17% to as high as 82%, with the lowest rates largely concentrated in rural areas. Experts say protection provided by herd immunity when vaccination rates fall below 95%. Officials recommend that not only pregnant people get their Tdap shot but also infants and children, adolescents, unvaccinated adults and anyone who spends regular time with a newborn.

According to the Oregon Health Authority, the recent surge in whooping cough follows unusually low case counts during the COVID-19 pandemic, when masking and social distancing reduced the spread of many respiratory illnesses. Health officials said the return to pre-pandemic social behavior and lower vaccination rates, has created ideal conditions for the disease to spread.

Part of the challenge, doctors said, is that pertussis can be difficult to diagnose. Not everyone develops the classic “whooping” cough, and some adults experience only mild symptoms — all while remaining contagious. Health officials said vaccination is the most effective way to prevent serious illness and hospitalization from whooping cough.