Rescue of Severely Immunocompromised HIV‐Positive Persons. Part 6
This varicella outbreak in a facility for adults with intellectual and physical disabilities highlights several important aspects of varicella prevention and control. Residents affected by this outbreak had been living in residential settings for most of their lives. This presumably resulted in greater social isolation and fewer opportunities for exposure to varicella in childhood. Although current guidelines from the Advisory Committee on Immunization Practices state that birth before 1980 is evidence of varicella immunity for the general population, this may not be predictive of immunity for individuals who have lived in residential facilities since childhood. As a result of the outbreak, the Connecticut Department of Developmental Services amended its varicella guidelines for similar institutional settings to no longer accept birth before 1980 as evidence of varicella immunity for residents. Because of challenges in obtaining complete medical and vaccination histories and collecting serum specimens, it can be difficult to determine varicella immunity among residents of adult residential facilities. Thus, for residents for whom it is difficult to document a history of varicella disease or vaccination and challenging to obtain a serology specimen to assess immunity, the most efficient approach may be to screen all current and potential residents for evidence of immunity to varicella and to vaccinate susceptible individuals, even those born before 1980, prior to admission to the facility.
Varicella outbreaks have been described in other residential facilities for adults, including long‐term care facilities, hospitals, and prisons, but few have been described in residential settings for people with intellectual and physical disabilities. Other than young age at admission to a residential facility, we did not find any individual level risk factors for varicella among residents in this outbreak. Because most adults have naturally acquired immunity to varicella, varicella disease in adult settings typically does not spread extensively. Although the overall attack rate in this outbreak was high (16%) compared with that for other reported outbreaks among adults (0.2%–3.6%), disease presentation was not particularly severe. Adults, however, often have more severe disease with increased rates of mortality when they develop varicella. A varicella outbreak among adults with learning disabilities, the majority of whom have lived most of their lives in a residential facility in the Netherlands, resulted in a varicella‐related death.
Varicella is highly infectious; secondary attack rates in susceptible household contacts might reach 90%. Recommended control measures, such as airborne respiratory isolation measures or isolation of case patients to their own room, can be extremely difficult and expensive for residential facilities to implement. Case patients in this outbreak could not be effectively isolated alone in their rooms because they required 24‐h supervision for their personal safety. Due to their level of disability, residents did not have the capacity to follow basic infection control practices.