The measles outbreak in Ohio continues to swell, striking a total of 63 children to date. The tally now includes at least three children who were partially vaccinated against the highly contagious virus and 14 who are typically too young to be vaccinated.

The measles, mumps, and rubella (MMR) vaccine is a two-dose vaccine, with the first dose recommended between the ages of 12 months and 15 months and the second between ages 4 and 6. According to the Centers for Disease Control and Prevention, just one MMR dose is estimated to be 93 percent effective against measles. Two doses are 97 percent effective. People who get their two doses on the recommended schedule are considered protected for life.

It's unclear if the three partially vaccinated children were too young to be eligible for their second dose or contracted measles quickly after getting their first dose, potentially before full protection developed. Health officials in the affected areas of Ohio have been promoting vaccination, which may have led some parents to get their eligible children freshly vaccinated amid the heightened awareness. The affected areas in Ohio span at least two counties: Franklin County, which encompasses Columbus, and Ross County to the south.

Advertisement

Most of the cases are in completely unvaccinated children who are in the age range eligible for at least one dose. Of the 63 total cases, 49 are between the ages of 1 year and 17 years, with most (29) between the ages of 1 and 2 years, according to a dashboard set up by the Columbus health department. At the time of this reporting, the dashboard was last updated on December 8. Of the 63 total cases, 60 were unvaccinated, with 46 being age 1 or older.

Twenty-five of the 63 cases have required hospitalization.

The outbreak, which began at the beginning of November among unvaccinated children without travel history that could explain exposure, is thought to be linked to four travel-related cases reported early in the year in Ohio. In addition to being a potentially life-threatening infection in young children, measles also suppresses immune responses for weeks to months after an infection, leaving children with heightened susceptibility to other dangerous infections.

Measles is considered eliminated in the US, in that it has not spread continuously in the country since at least 2000, though it is occasionally brought into the country via travel exposure. Slipping vaccination rates amid dangerous antivaccine misinformation and pandemic-related disruptions to health care now threaten the country's status. The US nearly lost its elimination status in 2019 amid a lengthy outbreak.

In a press conference last week, Mysheika Roberts, public health commissioner for Columbus, said at least 25 percent of the area's 2-year-olds are unvaccinated. She added that the health department is now working closely with the CDC and that the outbreak is expected to last for several months.