Tuolumne County Public Health Department confirmed Wednesday that two measles cases per day after an investigation into possible infections.
The department said the cases involved an adult and a child under the age of 18 who lived in the same family and traveled internationally. It is not clear whether these people have been vaccinated with measles, a highly contagious and potentially fatal disease that is most commonly found in high fevers and rashes.
The department said Tuesday it was investigating measles cases and warned of potential exposure between the Summerville High School in Tuolumne and the Adventist Health Sonora emergency room between March 15 and March 16.
“We know there may be a lot of questions and concerns. The investigation is still ongoing and we will provide updates where available,” the county’s public health director Michelle Jachetta said in a statement Wednesday. “We want to remind the public that measles is a highly contagious disease and take steps to protect yourself and your family by ensuring the current measles vaccination status, monitoring symptoms and staying at home when you feel nausea.”
Somerville United High School District Chief Michael Merrill also issued a statement saying the district “takes seriously the health and safety of its students, staff and our community” and that the school will work with public health officials by “determining any risks.” According to its website, more than 430 students attend Somerville High School.
The Tuolumne County case was a deadly measles outbreak that began in January in the South Plains and Panhandel area of Texas, and has since infected 279, accounting for the vast majority of more than 300 confirmed cases in 15 states so far this year. An uninoculated school child in Texas died of illness in February.
The California Department of Public Health reported Thursday that there were at least eight confirmed cases of measles in the state this year. They have not published the location of the case yet.
Tuolumne County reported some of the state’s lower vaccination rates during the 2023-2024 school year, according to data released this week by the state’s public health department.
Only 89.8% of Tuolumne County kindergarten students have the latest vaccines, compared with 93.7% of kindergartens across the state. Only 93.1% of kindergarten students received their measles, mumps and rubella shots, which were significantly below the statewide average of 96.2%. California usually publishes vaccination rates for a few grades, including kindergarten, first and seventh grades.
Public health experts say the vaccination rate is 95%, sometimes called “herd immunity” and is often considered the gold standard for preventing diseases. Even a slip of one or two percentage points can create opportunities for the spread of the disease, which means that even if the vast majority of children are vaccinated, in areas where the immunity rate drops below 95%, it still takes only a few cases to trigger an outbreak.
California reports that the share of kindergarten students fell last year despite strict laws making it difficult for parents to skip their kids’ shooting. Among them is 16 counties, where measles immunity is already below the herd immunity threshold.
Richard Pan, a former state senator of Sacramento Democratic, said the increase in vaccine hesitation in recent years, coupled with widespread disinformation online, could make encouraging immunization more difficult.
“We seem to be in the wrong direction,” Pan said. “We’ve always felt comfortable, like, ‘We’re OK.’ But we’re suddenly proving to people that it’s not OK.”
