Having dealt with measles outbreaks in 2014 and 2015, Shruti Gohil, MD, director of infection control in the University of California, Irvine Medical Center, was ready when her first measles case of 2019 was recently admitted.

Healthcare workers at Gohil’s hospital must provide evidence of measles vaccination or show immunity through blood titers.

“We require either you show evidence of prior immunization — you received two doses of MMR,” she says. “If you do not have hard documentation of that, we require titers that show if you are immune.”

Another immediate priority was reinforcing the signs and symptoms of measles to ensure case identification.

“There are a whole host of doctors who are on the front lines who have never actually seen a real measles case,” she says. “We need to make sure we understand the signs and symptoms of measles and how to recognize the syndrome.”

Suspect cases should be put in isolation in a negative pressure room and tested for measles. Remind healthcare workers that measles is a true airborne pathogen, reinforce policies with signage, and set up a triage plan, she recommends.

“Triage patients at the earliest opportunity to minimize exposures in the hospital,” she says.

All of these measures are key to prevent an undiagnosed case from sitting in the ED, exposing staff and patients and triggering a labor-intensive follow-up.

“If you do have an exposure in your hospital, you must assess your common area air space and decide how big the group is that could have been exposed,” Gohil says. “Then, identify whether everybody has blood titers [showing immunity] or has been vaccinated.”

Exposed workers who have no immunity should be vaccinated or administered immune globulin intramuscular post-exposure prophylaxis (PEP), depending on their risk factors. Generally, measles PEP must be administered in less than 72 hours and is usually reserved for infants, pregnant women, or the immune-compromised.

As of May 24, 2019, 940 cases of measles have been confirmed in 26 states, the CDC reports. That represents the greatest number of cases reported in the U.S. in 25 years. There also have been 535 confirmed cases of measles in Brooklyn and Queens since September 2018. Most of these cases have involved members of the Orthodox Jewish community.

“We have been working with all types of healthcare facilities in New York when there have been patients suspected of having measles,” says Karen Alroy, DVM, MPH, an officer in the CDC’s Epidemic Intelligence Service (EIS). “Measles virus is particularly challenging because a person can shed the virus four days before the rash develops.”

The CDC estimates about 4% of measles cases in outbreaks are acquired in healthcare facilities, Alroy says.

Two doses of the MMR vaccine are about 97% effective at preventing measles. One dose is about 93% effective. But measles is resurging, as parents decline to vaccinate their children. Some cite religious objections, unfounded fear that vaccines are linked to autism, or the perception that vaccination is unnecessary because measles is so rarely seen in the U.S.

Public health officials are cracking down, knowing that 400 to 500 children died annually of measles in the prevaccine era.

On April 9, the Health Commissioner of New York ordered every adult and child who works or resides in four ZIP codes in the outbreak area to be vaccinated if they had not already done so, previously contracted measles, or have a medical exemption.

“If the Health Department identifies a person with measles or an unvaccinated child exposed to measles in one of the above ZIP codes, that individual or their parent or guardian could be fined $1,000,” the department warned.

“The longer these outbreaks continue, the greater the chance that measles will again get a foothold in the United States,” Nancy Messonnier, MD, director of the CDC’s National Center for Immunization and Respiratory Diseases, said at a recent press conference.

It has been generally estimated that dipping below a 95% vaccination level in a population could undermine herd immunity and lead to ongoing transmission and sporadic cases.

“That is an important thing to be talking about,” Gohil says. “If we lose enough of the people who are [typically] vaccinated, we could roll this backward.”

The ongoing outbreak in New York City has resulted in a high volume of incoming suspect cases in both hospital EDs and outpatient settings. Hospitals generally have negative pressure rooms to isolate suspect or confirmed cases, but clinics and outpatient settings have had to get creative to prevent transmission from incoming cases.

“The virus can stay in the air for up to two hours,” says Alroy, the EIS officer fighting the outbreak in New York. “Often, a hospital will generate a list of who was exposed.”

In addition to designating an outside assessment area, facilities that have access to a separate nearby building may set up exam rooms there.

“In New York City, all healthcare providers are required to have immunization against measles virus,” she says. “If other staff members are in those buildings, they should already be protected.”

Other strategies include having suspect measles cases use specific entrances and exits designed to minimize exposure.

The 2019 outbreak has been fueled in large part by travelers to areas with international outbreaks returning to a U.S. community that has low MMR vaccination rates. The top three countries where importations are coming from are the Ukraine, Israel, and the Philippines, the CDC reports.