Since the beginning of November, 64 measles cases have been confirmed in children and teens in and around Columbus, Ohio, according to an update from state health officials on December 9. So far, 25 kids have been hospitalized with severe infections. The majority of cases — more than 90 percent — struck children age 5 years or younger. More than half the patients were infants or toddlers. Three of the infected children had received the first, but not the second, dose of the recommended measles, mumps, and rubella (MMR) vaccine. The other 61 were unvaccinated. While many were too young to be fully vaccinated, others were old enough to have had their shots but had not.
Measles Vaccination Rates Have Fallen to Decade-Low
The U.S. Centers for Disease Control and Prevention (CDC) recommends that kids get their first dose of the MMR vaccine when they’re 12 to 15 months old and a second dose when they’re between 4 and 6 years old. One dose is about 93 percent effective at preventing measles, while the two-dose series is about 97 percent effective, according to the CDC. Measles vaccination rates fell to the lowest level in more than a decade during the COVID-19 pandemic, complicating efforts to prevent outbreaks, according to a joint report by the World Health Organization and the CDC. “The record number of children under-immunized and susceptible to measles shows the profound damage immunization systems have sustained during the COVID-19 pandemic,” said the CDC’s director, Rochelle Walensky, MD, MPH, in a November 23 news release.
Measles Is Highly Contagious, Infecting 9 in 10 Unvaccinated People Who Are Exposed
In the Ohio outbreak, public health officials identified several exposure sites that are typical places parents might go with their children during their day-to-day routines: a Dollar Tree store, the Macy’s and JCPenny stores at the Polaris Mall, the Jesus Power Assembly of God church, and a Meijer supercenter store. It’s easy for measles to spread in public places like this because the virus is highly contagious. Nine in 10 people who aren’t fully vaccinated become infected when they’re exposed to the virus, according to the CDC. Infected individuals can spread the virus for several days before and after telltale rashes appear that are a hallmark of these infections. The virus can also survive up to two hours on surfaces, and people can easily become infected by touching these contaminated surfaces then rubbing their eyes, nose, or mouth. People can also become infected by breathing in droplets after somebody with measles coughs or sneezes. Infections often begin with a fever, followed by a cough, runny nose, or pink eye. Rashes on the face and neck appear next, then spread to the rest of the body. In the most serious cases, people can develop pneumonia and encephalitis, or inflammation in the brain, which can be fatal.
Does the U.S. Have Herd Immunity for Measles?
At least 95 percent of the population needs to be fully vaccinated against measles in order to achieve and maintain what’s known as herd immunity, when enough people are inoculated to effectively eliminate the spread of disease. Because measles spreads easily, slight dips in vaccination rates can lead to a large spike in cases. A study published in April 2019 in the Annals of Internal Medicine found that a 5 percent decline in measles vaccination rates could triple the number of cases. As of 2016, only about 91 percent of U.S. children had received at least one dose of the measles vaccine — too few to create herd immunity. Measles had been eliminated in the United States in 2000. But there were almost 1,300 cases in 31 states in 2019 — the highest number recorded since 1992, the CDC reported. All the measles outbreaks that year involved people who weren’t fully vaccinated. There have been several large measles outbreaks in the United States in recent years, including a multistate outbreak that originated at Disneyland in California that resulted in 147 cases, and an outbreak within several close-knit Orthodox Jewish communities in New York City and New York state that resulted in more than 280 cases.
