Measles: Identify Potential Cases, Move Swiftly to Prevent Exposures

By Dorothy Brooks

In just the first three months of this year, there were already more confirmed measles cases in the United States than in all of 2023, according to the Centers for Disease Control and Prevention (CDC). By the end of March, the agency reported 64 confirmed cases in 2024 — six more than the CDC documented in the entirety of 2023. In response, the agency has issued a Health Alert Network (HAN) advisory to healthcare providers, underscoring the high risk of transmission among people who have not been vaccinated against the viral illness.¹

Healthcare settings like the emergency department (ED) need to be especially attuned to the risks posed by a patient presenting with such a highly transmissible virus. For instance, hundreds of people were exposed to measles when a child with the virus presented to the ED at UC Davis Medical Center in Sacramento, CA, on March 5.

In a statement about the incident provided to EDM, the health system indicated it was working with local health officials to contact the roughly 300 people who were in the ED when the patient with measles was evaluated. “UC Davis has a record of each patient and employee who was in the ED that day and notifications about potential exposure are taking place through the electronic medical records online messaging portal, letters, in person, and over the phone,” the health system stated. “Only those people deemed at risk of exposure that afternoon and evening are being contacted.”

Of particular concern with such an incident are any patients or staff who may not have been vaccinated against measles. Children younger than 1 year of age are particularly vulnerable, since measles vaccines typically are not given until children are 12 months of age. Individuals who cannot receive the live measles vaccine because of an underlying medical condition also are at risk.

While the incident at UC Davis Medical Center is just one of several cases of measles that have been confirmed in California in 2024, cases also have been identified in at least 16 other states, including Arizona, Florida, Georgia, Illinois, Indiana, Louisiana, Maryland, Michigan, Minnesota, Missouri, New Jersey, New York, Ohio, Pennsylvania, Virginia, and Washington.²

“The reason that we’re seeing this increase in cases and outbreaks, even though measles was declared eliminated from the U.S. many years ago, is primarily because of unvaccinated travelers — mainly U.S. residents who are visiting countries where measles continues to circulate and then [they bring the disease] back to their communities here where it causes outbreaks in those who are also unvaccinated,” noted Sarah Lim, MD, a member of the public policy and advocacy committee for the Infectious Diseases Society of America (IDSA) and a medical specialist with the Minnesota Department of Health. “This is happening at the same time as we’re seeing a significant increase in measles globally, primarily because of declining vaccination rates due to the disruption of the COVID pandemic.”

Speaking at an IDSA briefing about the uptick in cases on March 12, Lim highlighted data from the World Health Organization, indicating that in 2022, only 83% of children had received a dose of measles vaccine by their first birthday — the lowest level of vaccine coverage in this group since 2008.

“Here in the U.S. for the 2022 to 2023 school year, our range for measles vaccine coverage for kindergartners is only 92%. These numbers sound high, but because measles is so contagious, vaccination rates need to be 95% or higher to contain transmission,” said Lim. “It’s not enough to have high national coverage. Every state in every community needs that high level and that’s not happening.”

Lim stressed that measles is one of the most contagious viruses known, indicating that one person with the disease can infect anywhere from 12 to 18 other people. “It is airborne and spreads through tiny droplets,” she stated. “When an infected person coughs or sneezes, if someone is unvaccinated and exposed, nine times out of 10, that person will go on to develop the disease.”

While health officials know how to prevent large outbreaks with the use of isolation and quarantine measures, it can be difficult to act fast enough to prevent transmission in a crowded setting such as the ED. Another complication is the fact that many providers have never seen a case of measles, so it is important for hospitals to ensure that frontline providers have a heightened suspicion level for the disease, and that they are well-briefed on what signs and symptoms are suggestive of the disease.³

“Vaccines have been so successful that we all collectively have forgotten what these childhood diseases look like, and some people don’t understand why we get so worried when we see measles cases increasing,” said Lim. “The reason is that even an uncomplicated case of measles is really awful. Children have high fevers, coughs, runny nose, red watery eyes, and a full body rash, which is really uncomfortable.”

Lim adds that 30% of children develop complications from measles that can include diarrhea, ear infections that can lead to permanent deafness, pneumonia, and encephalitis, which can lead to brain damage or epilepsy. “About 25% of children [who develop measles] are hospitalized, although it is not uncommon to see rates higher than that during an outbreak,” she observed.

Not only do frontline providers need to know what to look for in terms of the signs and symptoms of measles, but they also need to be thinking about a patient’s vaccine status and travel history. “Then it’s about trying to identify cases as soon as possible because of the risk of exposure,” noted Lim. “In a healthcare setting, you have children who are extremely vulnerable because they may be too young to be vaccinated … or oncology patients who can’t receive live vaccines because they’re on chemotherapy, so you really need to identify cases quickly and then, during their contagious period, they need to be in [a room with] airborne isolation within a healthcare setting to prevent onward transmissions.”

Joshua Barocas, MD, an associate professor of medicine in the divisions of general internal medicine and infectious diseases at the University of Colorado School of Medicine, also spoke at the IDSA briefing, noting that misinformation, particularly around vaccine safety, is plentiful. However, he stressed that it is up to clinicians and public health officials to advocate for what works best based on the best evidence. “The lesson that we have taken to heart is that we need to make sure that we are keeping the public up to date … when new science arises,” he shared. “That said, specifically regarding vaccine safety, we have seen decades of safety data and there is no reason to believe that vaccines are anything but helpful when it comes to preventing measles.”

Barocas also stressed that it is clear that pandemic preparedness needs to be an ongoing priority in local communities and local hospitals, but also in terms of federal support. “This is an opportunity not just for hospitals to be prepared, but for the U.S. government to help fund some of these [pandemic preparedness] initiatives and to boost the preparedness workforce, which starts with frontline providers, hospital protocols, and international collaboration,” he said.

REFERENCES

1. Centers for Disease Control and Prevention. Increase in global and domestic measles cases and outbreaks: Ensure children in the United States and those traveling internationally 6 months and older are current on MMR vaccination. CDC Health Alert Network. March 18, 2024. https://emergency.cdc.gov/han/2024/han00504.asp
2. Centers for Disease Control and Prevention. Measles cases and outbreaks. Last reviewed March 8, 2024. https://www.cdc.gov/measles/cases-outbreaks.html
3. Centers for Disease Control and Prevention. Measles symptoms and complications. Last reviewed Nov. 5, 2020. https://www.cdc.gov/measles/symptoms/index.html