Minnesota is reporting the highest number of whooping cough cases in more than a decade, the state Department of Health says.

As of last Wednesday, 2,324 cases of whooping cough, also called pertussis, were reported by health care facilities, medical labs and schools and child care centers, with the majority in the Twin Cities metro.

That's the highest number reported at this time of year since 2012, when there were 4,144 cases.

Health officials expected the spike because the disease peaks every three to five years. Whooping cough cases are increasing across the country, signaling a return to more typical trends seen before a drop-off of many contagious illnesses during the COVID-19 pandemic.

In Minnesota, the median age of those with whooping cough this year is 14. According to the Health Department, immunity from the vaccine — a shot routinely recommended for ages 11-12 — starts to wane after one or two years.

Among the cases, 77 infants were reported to have whooping cough, and 34 people were hospitalized.

Whooping cough often resembles a cold in the initial weeks before developing into the prolonged cough that gives the disease its name. People with the illness are contagious for the first 21 days of coughing or until they have completed the first five days of antibiotics.

The Health Department reports that vaccination is crucial in preventing and reducing the spread of whooping cough. Officials have voiced concerns as immunizations have declined in recent years among Minnesota kindergartners entering school.

Health officials urge women who are pregnant to receive the vaccine and that children receive on-time vaccinations. The whooping cough vaccine is included in a shot combined with tetanus and diphtheria vaccines.

Adults are urged to receive a booster shot every 10 years.