The flu season may be peaking in Michigan.

State health officials on Friday reported “widespread” flu activity, the highest level of outbreak, joining 15 other states.

Dr. Dean Sienko, the state’s acting chief medical executive, said there has been a marked increase in the number of flu cases.

“The flu season is nearing a peak or may indeed be peaking in our state,” he said, noting that the number of reported visits to doctors for flu-like symptoms doubled in a week.

Sienko urged people to get a flu shot and regularly wash their hands and cover their mouth when coughing or sneezing. The vaccine is available from local health departments and physicians. It takes about two weeks to become effective.

So far, the flu season has been mild compared with recent years, Sienko said, though some schools have been forced to close temporarily because students had flu-like symptoms.

While it’s tough to keep active schoolchildren from spreading the illness among each other, Sienko said, the flu rarely causes serious complications for them, besides a day or two of missed school.

The state health lab has confirmed 123 cases of the flu, but officials stressed the number is much higher.

According to a survey of doctors, 5.4 percent of office visits in Michigan are for flu-like illnesses, more than double the nationwide rate of 2.5 percent. The hardest-hit areas are southwestern and central Michigan.

Symptoms of the flu include fever, headaches, dry coughing, sore throat, tiredness and muscle aches. Each year, as many as 40,000 people, especially seniors, die in the United States from complication of influenza.

Earlier in the season, health officials were concerned about a shortage of flu vaccine. Michigan initially restricted vaccine use to high priority groups such as senior citizens, young children, pregnant women and people with chronic medical conditions such as asthma.

That order has been lifted, making vaccine available to anyone who wants it.