Varicella Immunity among Institutionalized Adults in a Long-Term Care Facility, Georgia

Background:
The 2006 ACIP criteria for evidence of varicella immunity includes being born in the U.S. before 1980 (except for pregnant women, immunocompromised persons, and health care workers [HCW]). Although it is well documented that >96% of adults over age 20 in the U.S. have immunity to varicella, limited information is available on immunity among adults who have spent significant time in long-term care institutions. In September 2008, varicella infection was identified in a resident of a long-term care facility for developmentally disabled adults (Facility A) in Georgia. The case-patient's roommate had been diagnosed with shingles two weeks earlier. Most HCW and residents in Facility A were born before 1980 (91%), but had limited documentation of varicella immunity.

Objectives:
To evaluate immunity to varicella infection among Facility A residents and HCW born in the U.S. before 1980.

Methods:
Varicella disease and vaccination histories were taken from Facility A HCW and residents. Varicella serology testing was performed at Georgia Public Health Laboratory for 30 Facility A residents and 26 HCW with unknown history of varicella immunity.

Results:
One HCW (1/26, 0.04%) and five long-term care residents (5/30, 17%) born before 1980 were found by serology to be susceptible to varicella infection. All others had serologic evidence of immunity or documentation of immunization.

Conclusions:
The ACIP criteria of birth before 1980 as evidence of varicella immunity may not be applicable to persons living in long-term care institutional facilities. This special population may not have had the same opportunities for exposures to varicella as other adults.