CDC: Review mumps immune status of HCWs

Mumps prevention addresses all hospitals

With mumps continuing to spread in at least 11 states, the Centers for Disease Control and Prevention (CDC) is recommending that all hospitals review the immune status of health care workers.

Health care workers should have documentation of two doses of the MMR vaccine or evidence of immunity, the Advisory Committee on Immunization Practices (ACIP) agreed in a special meeting held in May.1 While birth before 1957 previously had been considered evidence of immunity, ACIP says hospitals should consider providing one dose of MMR vaccine to those health care workers, if they are unvaccinated.

During an outbreak, those older workers should receive two doses of the MMR vaccine, given at least 28 days apart, says ACIP, a panel of experts that helps draft CDC guidance. Hospitals may also conduct serologic testing to determine immunity.

If health care workers report a history of mumps but do not have documentation of a physician diagnosis, they should either be vaccinated or undergo serologic testing as well, the CDC advises.

Reviewing the immunity of employees is a time-consuming task, acknowledges Arjun Srinivasan, MD, medical epidemiologist with the CDC's division of health care quality promotion.

"The ideal time to do this would be during other immunizations or screenings of health care workers, such as influenza vaccination," he says.

It's certainly preferable to check the immune status of employees when there's no outbreak, he says. "Doing things in a setting of an outbreak is very, very difficult," he says.

And, as the outbreak continues, it could spread to additional states. As of May 2, the CDC reported 2,597 cases of confirmed, probable, or suspect mumps, with a majority of the cases (57%) occurring in Iowa. Mumps have also been reported in other Midwestern states, including Kansas, Nebraska, Illinois, and Wisconsin.

While mumps initially spread on college campuses, and have occurred most frequently among young adults (37%), it has affected all ages, the CDC reports. More than half have received two doses of the vaccine.

"It's not concerning to see a high [percentage] of cases among two-dose vaccinees. That's what we would expect," says Jane Seward, MBBS, MPH, acting deputy director of the CDC's division of viral diseases, in a teleconference, noting that the vaccine is about 90% effective.

However, the CDC does not recommend serologic testing of those who have been vaccinated. Seward notes that vaccination doesn't provide the level of antibody produced by natural infection. "Consider two doses of vaccine adequate evidence of immunity," she says.

That means that even some vaccinated health care workers can contract mumps; so employees must be aware of the possible symptoms. In the current outbreak, only about half of the mumps cases involved the classic "parotitis," or swollen salivary glands. Another 20% were asymptomatic, and 30% had nonspecific respiratory or influenza-like symptoms, Seward says.

Vaccinated health care workers who have been exposed to mumps can continue working, says Seward. However, nonimmune health care workers should be furloughed from the 12th day after exposure to the 26th day after the last exposure.

(Editor's note: Mumps guidance for health care facilities is available from www.cdc.gov/nip/diseases/mumps/control-hcw.htm. The teleconference can be viewed at www.izcoalitionsta.org/confcall.cfm.)

Reference

1. Centers for Disease Control and Prevention. Update: Multistate Outbreak of Mumps—United States, Jan. 1-May 2, 2006. MMWR Morb Mortal Wkly Rep. 2006;55:559-563.