Alaska’s outbreak of pertussis, commonly known as whooping cough, has now subsided, but it created some significant impacts for residents, state data shows.
The outbreak ran from April 2024 to 2025. During that 12-month period, there were 679 confirmed or probable cases reported in the state, said a newly released bulletin from the Alaska Division of Health’s epidemiology section.
Pertussis is caused by a bacterial infection and is highly contagious.
Among them were 74 infants younger than 1 who got the disease, most were not up to date on their vaccinations, the bulletin said.
Twenty-nine patients were hospitalized, most of them infants under 1 year old, the bulletin said.
One unvaccinated baby died during the outbreak, the bulletin said.
Vaccination provided significant protection to Alaska children, earlier research showed.
In the summer and fall of 2024, when the outbreak was at its peak, unvaccinated Alaska children were more than 13 times as likely to contract the disease than those who had received all their pertussis vaccinations, the bulletin said.
The peak of the outbreak was in September 2024, when there were 155 cases reported statewide. That peak coincided with a big uptick in vaccine orders in late summer of 2024, and a record number of vaccines were given to Alaskans in September, Dr. Elizabeth Ohlsen, a staff physician with the epidemiology section, said by email.
“Overall, we are glad to see that the vast majority of Alaskans choose to protect themselves and their children against pertussis” by adhering to the recommended immunization schedule, Ohlsen said.
The pertussis vaccine is combined with vaccines for diphtheria and tetanus. The recommended schedule includes vaccination of expectant mothers during their third trimester of pregnancy – the only available protection against the disease for the youngest infants. For children, the recommended schedule is for four doses by 18 months of age, followed by a booster when children are between 4 and 6. Boosters are also recommended every 10 years for teens and adults.
Ohlsen emphasized the need for vaccination during pregnancy.
“This boosts maternal immunity in a way that gets passed on to the infant. This is so important because infants <6 months old are the most likely to get seriously ill if they get pertussis,” she said by email.
By geography, about a third of the reported cases were in Anchorage and 20% were in the Matanuska-Susitna Borough. The rest were scattered around the state.
While Anchorage had the highest number of cases, 228, it had the lowest rate among the state’s regions: 78 per 100,000 people. The Southwest region, with 82 cases, had the highest regional rate, at 198 per 100,000 people, the bulletin said.
Alaska’s outbreak happened at about the same time as a national surge in the disease that peaked in November, according to the U.S. Centers for Disease Control and Prevention.
