Michigan health officials are encouraging parents during National Infant Immunization Week to make sure their children have all their vaccinations.

That message takes on an added urgency this year with ongoing measles outbreaks nationwide, including Michigan, which reported new cases of the disease earlier this month. Montana joined the list Monday as the ninth state this year with an outbreak, defined as three or more cases, according to the Associated Press.

Other states with active measles outbreaks are: Indiana, Kansas, Oklahoma, Ohio, Pennsylvania and New Mexico. The U.S. has had 800 measles cases in 2025 as of Friday, with Texas accounting for nearly 600 of those cases. Two children and an adult have died from measles-related illnesses.

Measles is caused by a highly contagious virus that’s airborne and spreads easily when an infected person breathes, sneezes or coughs. It is preventable through vaccines, and had been considered eliminated from the U.S. since 2000, according to the Associated Press.

Elsewhere in North America, measles has sickened 925 in Ontario, Canada, from mid-October through April 16. In Mexico, the Chihuahua state has 433 cases as of April 18, according to data from the state health ministry; the World Health Organization has said the cases are linked to the Texas outbreak that started in January.

National Infant Immunization Week, which started Monday and extends through April 28, highlights the importance of protecting children 2 years old and younger from vaccine-preventable diseases. Global immunization efforts during the past 50 years have saved an estimated 154 million lives, including 101 million infants, MDHHS states in a news release.

“Vaccines are one of the most effective tools we have to keep children healthy and communities safe,” said Dr. Natasha Bagdasarian, chief medical executive. “With diseases like measles on the rise across the country, staying on schedule with childhood immunizations is more important than ever.”

The Centers for Disease Control and Prevention and the American Academy of Pediatrics recommends parents keep their children on schedule with well-child visits and routine vaccinations. Even small declines in vaccination coverage can result in an increase in the number of cases and outbreaks of vaccine preventable diseases like measles that can cause serious illness, hospitalization and death.

According to data from the Michigan Care Improvement Registry, as of Dec. 31, 2024, only 57% of children 19 months through 35 months of age were up to date with all recommended vaccines. This means nearly half of Michigan toddlers are not fully protected from vaccine-preventable diseases, MDHHS warned.

Parents should reach out to their health care provider to find out which vaccines are needed to ensure their child stays protected. For more information on vaccines, parents can go online to Michigan.gov/immunize or iVaccinate.org.