Background: When caring for measles patients, N95 respirator use by healthcare workers (HCWs) with documented immunity is not uniformly required or practiced. In the setting of increasingly common measles outbreaks and provider inexperience with measles, HCWs face increased risk for occupational exposures. Meanwhile, optimal infection prevention responses to healthcare-associated exposures are loosely defined. We describe measles acquisition among HCWs despite prior immunity and lessons from healthcare-associated exposure investigations during a countywide outbreak.
Methods: Primary and secondary cases, associated exposures, and risk factors were identified during a measles outbreak in Orange County, California from, 30 January 2014 to 21 April 2014. We reviewed the effect of different strategies in response to hospital exposures and resultant case capture.
Results: Among 22 confirmed measles cases, 5 secondary cases occurred in HCWs. Of these, 4 had direct contact with measles patients; none wore N95 respirators. Four HCWs had prior evidence of immunity and continued working after developing symptoms, resulting in 1014 exposures, but no transmissions. Overall, 13 of 15 secondary cases had face-to-face contact with measles patients, 8 with prior evidence of immunity.
Conclusions: HCWs with unmasked, direct contact with measles patients are at risk for developing disease despite evidence of prior immunity, resulting in potentially large numbers of exposures and necessitating time-intensive investigations. Vaccination may lower infectivity. Regardless of immunity status, HCWs should wear N-95 respirators (or equivalent) when evaluating suspected measles patients. Those with direct unprotected exposure should be monitored for symptoms and be furloughed at the earliest sign of illness.
Keywords: exposure investigation; healthcare worker immunization; measles; measles immunity; transmission of communicable disease.
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