Measles Cases Surge: Six Newborns Infected in Ontario

Rare Congenital Infections Linked to Unvaccinated Mothers

A concerning outbreak of measles in Ontario, Canada, has led to six newborns contracting the virus while still in the womb—a condition known as congenital measles. All affected infants were born to mothers who had not received the measles, mumps, and rubella (MMR) vaccine.

Growing Outbreak Raises Alarm

Kieran Moore, Ontario’s chief medical officer of health, confirmed the infants are recovering but stressed the infections were preventable through vaccination. These infections could’ve been avoided with routine vaccines. The cases are part of a significant measles resurgence—the largest seen in the Western Hemisphere in recent years.

Canada had previously eliminated measles in 1998, meaning it was no longer regularly spreading. However, with over 2,000 cases reported in Ontario since October—exceeding the total number of cases reported in the United States so far this year—that status is now threatened. According to the Centers for Disease Control and Prevention, the U.S. saw 125 cases of measles in 2024 as of April 26th, a significant increase from the 58 cases reported during the same period in 2023. (CDC Measles Data)

Understanding Congenital Measles

Congenital measles occurs when a pregnant woman contracts measles and transmits the virus to her baby before birth. While measles is dangerous at any age, it poses a particularly severe risk to newborns. Normally, a fetus receives some immunity from its mother, but this protection is absent if the mother is unvaccinated and becomes infected during pregnancy.

Early exposure to the virus can result in premature birth, low birth weight, and serious complications like brain inflammation (encephalitis). In the most severe instances, congenital measles can be fatal.

The MMR vaccine, while highly effective, contains a live virus and is not administered during pregnancy. However, if an unvaccinated pregnant person is exposed to measles, doctors recommend intravenous immunoglobulin to potentially prevent infection. Acceptance of this treatment is not universal, often due to personal or philosophical beliefs.

Preventative Measures and Rising Concerns

Although rare, especially in countries with high vaccination rates, congenital measles is becoming a growing concern due to outbreaks and increasing vaccine hesitancy. Public health initiatives and informed decision-making are crucial to minimizing—and ideally eliminating—this preventable risk.