As of Oct. 3, 2019, there have been 1,250 confirmed cases of measles this year in 31 states, the CDC reports.1

Vaccine avoidance based on misinformation and unfounded fears is the main reason for the return of this once-eradicated disease in the United States. Facing the possibility of outbreaks or chaotic introductions of even a single case, many facilities are reviewing their healthcare personnel immunity status and furlough policies for measles.

Hilary Babcock, MD, MPH, Medical Director at Occupational Health at Barnes-Jewish and St. Louis Children’s Hospitals (BJC), is leading such an effort and outlined the project on Oct. 2 at the IDWeek Conference in Washington, DC.

Although her healthcare system has not seen measles cases, Babcock said regional reports of cases and the ongoing national situation make it a matter of “when, not if.” Declared eradicated in the United States in 2000, measles understandably fell off the radar at many hospitals. Immunization and related records may have suffered accordingly. Just as clinicians are relearning (or learning for the first time) how to recognize infected patients, it bears reminding that measles is one of the most infectious of the respiratory viruses — a true airborne agent that can linger in the environment.

“We are in the process of [updating] all of our employees’ immune status,” she said. “We ensured that we have the current isolation recommendation policies in place and that our policies reflect CDC guidance that all staff should be immune to measles, and, regardless of immune status, should wear N95 respirators in providing care for measles patients.”

As part of the proactive program, the hospital created measles room signage that calls for the use of airborne precautions with respirators while forbidding entry to nonimmune staff.

Typically, proof of measles immunity for healthcare workers includes documentation of childhood receipt of two doses of measles-containing vaccine. “Ideally, these are both given after the first birthday, with the second dose at least 28 days after the first.”

Laboratory evidence of immunity to measles — positivity for Rubeola IgG titer — also is acceptable proof of immunity. “As a reminder, an equivocal titer is considered negative,” she said.

The CDC says the old benchmark of birth before 1957 as proof of immunity generally is acceptable under normal conditions, but workers should be immunized if a measles introduction or outbreak occurs. These workers were targeted for titer check or immunization as the measles prevention program was undertaken at her healthcare system, Babcock said.

“I don’t see any reason we should wait for that to happen and then try to find all those people and get them vaccinated,” she said.

The BJC health systems and affiliated Washington University include some 30,000 employees across multiple facilities. Although some records were incomplete or laborious to access, Babcock and colleagues found around 3,500 employees with unknown measles immunity status.

“We had others that actually had documented nonimmune status,” she said. “They had only one MMR documented or documentation of a negative titer with no follow-up. We did wonder a little bit how that happened — that we have people in here documented to be nonimmune.”

Reviewing policy history over more than a decade showed somewhat different criteria during different periods. “Many hospitals had variable practices across our system and [varied in] how well they required them and what allowances they had for people to opt out of vaccination,” she said.

The next step was an outreach program to contact employees with unknown measles immune status and those with known nonimmune status.

“We requested documentation of two doses of vaccine, and if [they had] no documentation, we required them to have a titer drawn,” she said. “If the titer was negative, they needed to get MMR. We put timelines on those, so we notified they had to respond within a couple of weeks and then follow up and get the second dose.”

Cost-benefit analysis showed that getting titers to check for measles antibodies was better than simply immunizing everybody with unknown status.

“The cost of titer was lower than vaccine doses, and we hoped there would be plenty [of employees] who were immune — which turned out to be true,” Babcock said. “Many of our occupational health offices also used this as an opportunity to check mumps and varicella titers, and generally clean up vaccination records for the employees.”

Previously, the employee health offices had been notified about the effort, and the clinical labs were likewise ready to test a higher number of titers. The team drafted a medical exemption request form reflecting contraindications to MMR vaccine, including a prior severe reaction, pregnancy, or being immunocompromised.

“We alerted human resources of expected religious accommodation requests, which is a process that we have in place for our influenza mandatory policy,” she said.

The process is ongoing, but Babcock said at IDWeek that titers have been drawn on more than 2,600 employees. Around 2,100 of them have been positive.

“We have a little more than 80% immune documentation among people who didn’t know their status,” she said. “That has been good for us. We didn’t have to vaccinate those people and have clarified that they are considered immune.”

More than 800 MMR vaccines have been administered to those known or found not immune to measles. Such a massive effort does not come without some trepidation and concern by healthcare workers, so Babcock and colleagues began providing answers to frequently asked questions.

“Because it is a live virus vaccine that we can’t give to immunocompromised patients, many of our employees were worried that if they got this vaccine they would put highly immunized patients at risk,” she said. They were concerned about “transmitting to a patient or a family member who might be immunocompromised.”

Down the Rabbit Hole

On the contrary, by getting vaccinated, the healthcare workers were protecting patients and immunized family members who rely on the herd immunity of others to protect them from measles, Babcock emphasized.

“There have been no cases of vaccinated healthcare workers transmitting [measles] to patients,” she added. “The CDC recommends no work restrictions for people who have been vaccinated. This is true even if someone has been vaccinated and developed some symptoms like a rash or a low-grade fever. They are still not infectious. That is an immune response to the vaccine.”

Approximately 5-15% of susceptible persons who receive MMR vaccine will develop a low-grade fever and/or mild rash 7-12 days after vaccination. Again, they are not infectious and this does not require exclusion from work.

Other questions included those who received an ineffective measles vaccine in the 1960s. The CDC told Babcock and colleagues that it is estimated that less than 1 million people received this vaccine and there is no general recommendation to try to find them.

Specifically, the CDC said, “it is safe to assume if there is a record of vaccination that they are immune, unless it specifically can be verified that the healthcare personnel received a killed vaccine.”

“We did not go down that rabbit hole any further,” Babcock said. “If they have documentation from any period, we accept that.”

Questions also arose about licensed independent practitioners (LIPs), physicians, and allied health professionals who, technically, are not employees.

“This is always a challenge for occupational health services,” she said. “These are the people not employed by your facility but who provide services, see patients, and are credentialed to provide care.”

Babcock and colleagues worked through the credential verification office and sent letters to all LIPs reminding them of the criteria for immunity and the expectation that they should be immune.

“We provided information of several ways for them to clarify their status by getting labs drawn or finding their documentation,” she says. “We did remind them that if there are cases and exposures we could find them and we would furlough them and not allow them to come into our hospital.”

Exposure avoidance is the main goal through screening, masking, and patient isolation. However, questions come up about special situations like transporting patients within or between facilities.

“For most of us who are working with people who may be transferred between facilities, that staff in the ambulance or transport service needed to be immune and wear PPE,” she said. “If the patient can be masked, they should be.”

The ambulance should be taken out of service for two hours to allow the virus to dissipate and for the vehicle to be cleaned before use on another patient, she added.

“For transport within the facility, we usually try to mask the patient and not the transporters for most disease,” she said. “For measles, try to do both — mask the staff and the patient.”

Even if the patient is masked, Babcock recommended clearing the hallways during transport and airing out any elevators that were used.

As a member of the CDC’s Healthcare Infection Control Practices Advisory Committee (HICPAC), Babcock shared some draft guidance on measles exposures. The recommendations will be published as part of the ongoing rollout of the CDC guidelines for preventing occupational infections.

As shared by Babcock at IDWeek, the definition of exposure to measles for healthcare workers is “spending any time while unprotected — not wearing respiratory protection — in a shared air space with an infectious measles patient; or sharing an air space vacated by an infectious measles patient within the prior 2 hours, regardless of immune status.”

She conceded that “‘any time’ is a pretty high bar. I think it is not really practicable in a real-life setting, and there is a lot of discussion around that.”

There also are a lot of variables at play, like the air exchange of a given area and how effective and for how long to mask a measles patient.

“There are very little data about the role of source control and the impact of masking,” she said. “We recommend it for patients but we don’t really know how well that works. There also are no great data on duration.”

Clearly, there is higher risk in providing face-to-face care with neither the measles patient nor clinician masked. “[The CDC] can’t give a cut time, but obviously longer is worse,” Babcock said.

Similarly, quantifying the vagaries of “shared air space” is difficult. An ambulance, exam rooms, and small enclosed waiting areas can pose a risk, but it is considerably harder to determine the likelihood of exposure in large open waiting areas with shared air handing systems across different patient rooms, she said. If such a situation arises with measles, it may be best to consult with air handling and engineering at your facility, Babcock adds.

In another item from the upcoming HICPAC draft guidelines, post-exposure prophylaxis (PEP) and work restrictions are not necessary for healthcare personnel with presumptive evidence of immunity to measles who have experienced an exposure. However, implement daily monitoring for signs and symptoms of measles infection for 21 days after their last exposure, she said.

“Symptom monitoring is still recommended as we do know that there are cases in people with evidence of immunity after an exposure,” she said. “In some places, depending on your comfort level with risk, there may be different decisions made on how to manage this.”

For healthcare personnel without presumptive evidence of immunity who have experienced an exposure, the HICPAC draft recommends:

• Administer PEP according to recommendations by the CDC and the Advisory Committee on Immunization Practices;

• Exclude from work for the fifth day after the first exposure through the 21st day after their last exposure, regardless of receipt of PEP.

Healthcare workers who have only received the first dose of MMR vaccine prior to exposure may remain at work, but they should receive the second dose by at least 28 days after the first dose. Implement daily monitoring for signs and symptoms of measles infection for 21 days after the last exposure.

For healthcare personnel with known or suspected measles, exclude from work for four days after the rash appears. For immunosuppressed healthcare personnel who acquire measles, consider extending exclusion from work for the duration of their illness.

REFERENCE

  1. Centers for Disease Control and Prevention. Measles cases and outbreaks. Available at: https://bit.ly/2iMFK71. Accessed Oct. 28, 2019.