By Gary Evans, Medical Writer
A record resurgence of measles in 2019 includes two large, ongoing outbreaks in New York, where the Centers for Disease Control and Prevention (CDC) is helping hospitals and outpatient clinics prevent transmission from incoming cases.
“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.”
By April 29, 2019, the CDC already had reported a record 704 measles cases for the year, the largest number of cases in a year since measles was declared eradicated in the U.S. in 2000. The CDC estimates about 4% of measles cases in outbreaks are acquired in healthcare facilities, Alroy says. Applying that estimate to the 704 cases means some 28 people have acquired measles in a healthcare setting in the ongoing outbreak.
In light of several international outbreaks, the CDC is advising measles immunization for traveling children less than one year old while re-emphasizing the safety of the measles, mumps, and rubella vaccine. (See the related story in this issue.) In the pre-vaccine era, measles killed some 400 to 500 children annually and caused serious but survivable conditions.
“Of the 704 cases in 2019, 9% have been hospitalized and 3% have had pneumonia. At this time, there have been no deaths,” Robert Redfield, MD, CDC director, said at a recent press conference. “There is no way to predict how bad a case of measles may be. Some children may have very mild symptoms, but others may face more serious complications like pneumonia or encephalitis.”
A large outbreak in Washington state has ended, but outbreaks are continuing in New York, said Nancy Messonnier, MD, director of the CDC’s National Center for Immunization and Respiratory Diseases.
“The outbreaks in New York City and New York state are the largest and longest-lasting since measles elimination in 2000,” she said.
From October 2018 through April 29, 2019, there have been 423 confirmed measles cases in Brooklyn and Queens. Just north of the city, Rockland County, NY, had 214 cases as of May 3, 2019. Many of the New York cases are in members of the Orthodox Jewish community. The index case is thought to be an unvaccinated child who traveled to Israel, where there is a large measles outbreak.
Measles cases have been reported in 22 states, showing how travelers from outbreak areas domestically and internationally can lead to geographic disbursement. If someone with measles arrives in a susceptible community with low vaccination levels, another outbreak can begin.
“The longer these outbreaks continue, the greater the chance that measles will again get a foothold in the United States,” Messonnier said at the 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,” says Shruti Gohil, MD, director of infection control in the University of California, Irvine Medical Center. “If we lose enough of the people who are [typically] vaccinated, we could roll this backward.”
Having dealt with measles outbreaks in 2014 and 2015, Gohil was ready when her first measles case of 2019 was recently admitted. Among the immediate priorities 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 tells Hospital Infection Control & Prevention. “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 clinicians 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 these measures are key to prevent an undiagnosed case sitting in the ED, exposing staff and other 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.”
Those exposed who have no immunity should be vaccinated or administered IGIM (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 immunocompromised.
Healthcare workers at Gohil’s hospital must have evidence of measles vaccination or show immunity through blood titers.
“We require ... 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.”
The ongoing outbreak in New York City has resulted in a high volume of incoming suspect cases in both hospital emergency departments and outpatient settings. Hospitals generally have negative pressure rooms to isolate suspect or confirmed cases, but clinics and outpatient setting 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.”
The current guidance from CDC is that exposures could occur to anyone who shared a common space with a patient later confirmed to have measles — and anyone who entered that space for up to two hours afterward. This policy became overwhelming for outpatient facilities, which have little resources to track and alert potentially exposed patients.
“You can see a lot of patients in two hours in an [outpatient] practice,” she says. “So, we were seeing this large number of people potentially being exposed to the measles virus.”
Some of the outpatient facilities began adopting workarounds like asking patients with measles symptoms to call ahead or be evaluated by clinicians in an outside area.
“We heard of them doing some really creative low-cost strategies to help minimize the risks of exposing other patients,” she said. Alroy and colleagues surveyed1 facilities to see what was working so they could disseminate best practices to other sites.
“CDC recommends these outpatient facilities try to control droplet transmission by putting a mask on the patient, examining them in a private room, and then [leaving] that room unused for two hours after the patient leaves,” she says.
That approach directly controls droplet transmission, but there still is the possibility of airborne transmission depending on variables like how long the patient was unmasked in a common area.
“Somebody infected with measles can be sick with somewhat non-specific clinical signs such as cough, fever, and runny nose,” she says.
Some sites are screening patients by phone if possible, assessing symptoms and designating arrival plans. A sign in front of a clinic may say “call rather than enter if you have measles symptoms or have been exposed to someone who has measles.”
“The screening is super important — either by telephone, signs, or somebody standing outside the front door,” Alroy says. “Make sure to ask every patient if they are experiencing signs consistent with fever, cough, runny noses, and rash.”
Recent travel to an area that was experiencing a measles outbreak also is an important piece of information.
In addition to designating an outside assessment area, facilities with 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 be already protected.”
Other strategies being used include having a suspect measles case use specific entrances and exits designed to minimize exposure.
“Ideally, it would be in a place that was not in the same building or air space because the virus can travel by ventilation systems,” Alroy says. “Some facilities also are seeing suspect measles patients after normal hours or even doing home visits if possible.”
Even with signage posted, some hospitals have placed a staff member outside the emergency department entrance.
“The signs are great, but unfortunately in our society — where people are being bombarded with information all the time — people miss the signs and walk right by them,” she says.
The CDC is using serological tests for measles immunity and genetic tests that inform patterns of transmission. Results are generally available in one or two days.
“Another important thing is that staff members at these facilities — from the front desk to the doctors — should really be well versed about measles and know the signs and symptoms,” Alroy says.
“They should find out if transmission is happening in their area. Are there any particular parts of the city that they need to be aware of? Patients coming from those areas may pose a higher risk.”
The legacy of the 2019 measles outbreaks could be that it was a teachable moment that underscored the need for vaccination.
“I think that we are very fortunate in the U.S.,” she says.
“In 2000, endemic measles transmission was declared eliminated. That is largely because of the incredible power of the vaccine. We haven’t had to deal with our children or family members getting sick. We might have forgotten how serious of a disease this is.”
- Alroy KA, Vora NM, Rosen JB, et al. Interventions to Reduce Measles Exposures in Outpatient Healthcare Facilities — New York City, 2018. CDC EIS Conference. Atlanta, April 29–May 2, 2019.