MDHHS encourages urgent flu vaccination as influenza activity increases and new variant emerges

Vaccine also helps protect against new variant subclade K  

LANSING, Mich. – Influenza activity is increasing across parts of the United States, including in Michigan. The Michigan Department of Health and Human Services (MDHHS) encourages residents to take preventive steps now to protect themselves, their families and their communities as holiday travel and activities begin. 

Vaccination remains the most important tool for prevention of serious influenza illness. In alignment with National Influenza Vaccination Week, which is observed annually in early December, MDHHS urges everyone who is able to get their flu vaccine if they have not already done so. 

“The flu vaccine may not prevent mild illness, but data shows it reduces severe complications of influenza, including hospitalization, said Dr. Natasha Bagdasarian, Michigan’s chief medical executive. “Getting a flu vaccine now is a great way to boost your immunity against influenza through the winter months, when we tend see even more cases.” 

The United Kingdom (UK), Canada and other countries are experiencing an earlier and more intense start to their flu seasons, which have timing similar to the U.S. In the UK, cases normally peak between late December and early February. This year, there has been an influx of cases in November and that will likely continue to increase. The percentage of positive flu tests also continues to rise, reaching 13.3% as of Sunday, Nov. 9, which is higher than the approximately 4% it was at this time in 2024. The most recent UK influenza cases are caused by the H3N2 strain, and the majority of tested samples show a newer version of that strain called subclade K. UK’s trends may predict potential influenza activity in the U.S. 

Influenza viruses change over time, which is why global health experts track them closely. The World Health Organization reviews which strains are circulating each year to help guide the formula for the seasonal flu vaccine. This year’s vaccine was designed to protect against an H3N2 strain known as subclade J.2. Since development of this year’s vaccine, a newer variant called subclade K has emerged. In the UK, hospitals have noted higher than normal respiratory infections. Public health officials partially attribute these findings to subclade K’s efficient spread. The H3N2 strain tends to cause more severe illness than the H1N1 influenza subtype; Michigan typically sees circulation of both strains during each flu season.  

Despite the new variant, vaccine effectiveness estimates from the UK show that this season’s flu vaccine does provide protection and reduces serious outcomes, preventing 70-75% of flu-related hospital visits for children and 30-40% for adults. MDHHS strongly recommends prompt vaccination to protect against influenza and to reduce severity of virus symptoms and outcomes.  

According to the Michigan Respiratory Virus Immunization Statewide Summary, influenza vaccine coverage in Michigan for the 2025–2026 season is low at 18%. That means only about one in six people are protected, which raises serious concerns about the potential for high levels of illness, emergency department visits and hospitalizations, especially with the new influenza strain spreading quickly. The earlier start to the flu season also means that vulnerable populations that may not have received flu vaccinations yet are more likely to be at risk if exposed. 

The 2024-25 flu season serves as a reminder of how severe influenza activity can become. In Michigan, there were more than 33,000 hospitalizations between October 2024 and May 2025, with weekly hospitalizations peaking at more than 3,100 in February. Emergency departments saw nearly 8,600 influenza-related visits at the height of the season, almost double from the previous year.  

Flu also had a devastating impact on children and Michigan families, with 14 pediatric influenza deaths during the 2024–2025 season, the highest number recorded since the state began tracking pediatric flu mortality in 2004. This represents a significant increase from the eight deaths reported in each of the two prior seasons. The U.S. also experienced a record number of pediatric flu deaths last season. These losses highlight the critical importance of vaccination for all eligible children. 

MDHHS recommends all eligible persons 6 months and older get the annual flu vaccine. Other actions, such as staying home when sick, properly covering coughs and sneezes, washing hands frequently and improving indoor ventilation, can also help reduce the spread of influenza and other respiratory illnesses.  

For more information about statewide influenza trends, vaccine coverage and how to stay protected throughout the season, visit Michigan.gov/COVIDFLURSV. 

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