IntroductionIn January 2010, the Virginia Department of Health received reports of 2 hepatitis B virus (HBV) infections (1 acute, 1 chronic) among residents of a single assisted living facility (ALF). Both infected residents had diabetes and received assisted monitoring of blood glucose (AMBG) at the facility. An investigation was initiated in response.ObjectiveTo determine the extent and mechanism of HBV transmission among ALF residents.DesignRetrospective cohort study.SettingAn ALF that primarily housed residents with neuropsychiatric disorders in 2 adjacent buildings in Virginia.ParticipantsResidents of the facility as of March 2010.MeasurementsHBV serologic testing, relevant medical history, and HBV genome sequences. Risk ratios (RR) and 95% confidence intervals (CIs) were used to identify risk factors for HBV infection.ResultsHBV serologic status was determined for 126 (91%) of 139 residents. Among 88 susceptible residents, 14 became acutely infected (attack rate, 16%), and 74 remained uninfected. Acute HBV infection developed among 12 (92%) of 13 residents who received AMBG, compared with 2 (3%) of 75 residents who did not (RR  = 35; 95% CI, 8.7, 137). Identified infection control breaches during AMBG included shared use of fingerstick devices for multiple residents. HBV genome sequencing demonstrated 2 building-specific phylogenetic infection clusters, each having 99.8–100% sequence identity.LimitationsTransfer of residents out of the facility prior to our investigation might have contributed to an underestimate of cases. Resident interviews provided insufficient information to fully assess behavioral risk factors for HBV infection.ConclusionsFailure to adhere to safe practices during AMBG resulted in a large HBV outbreak. Protection of a growing and vulnerable ALF population requires improved training of staff and routine facility licensing inspections that scrutinize infection control practices.

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Background Failure to adhere to infection control guidelines, especially during assisted monitoring of blood glucose, has caused multiple hepatitis B outbreaks in assisted living facilities (ALFs). In conjunction with the response to such an outbreak at an ALF (“Facility X”) where most residents had neuropsychiatric disorders, we evaluated seroprotection rates conferred by hepatitis B vaccine and assessed the influence of demographic factors on vaccine response. Methods Residents were screened for hepatitis B and C infection, and those susceptible were vaccinated against hepatitis A and hepatitis B with one dose of TWINRIX™ (GSK) given at 0, 1, and 7 months. Blood samples were collected 1–2 months after receipt of the third vaccine dose to test for antibody to hepatitis B surface antigen (anti-HBs). Results Of the 27 residents who had post-vaccination blood specimens collected, 22 (81%) achieved anti-HBs concentrations ≥10 mIU/mL. Neither age nor neuropsychiatric comorbidity was a significant determinant of seroprotection. Geometric mean concentration was lower among residents aged 60–74 years (74.3 mIU/mL) than among residents aged 46–59 years (105.3 mIU/mL) but highest among residents aged ≥75 years (122.5 mIU/mL). The effect of diabetes on vaccination response could not be examined because 16/17 (94%) diabetic residents had HBV infection by the time of investigation. Conclusions Adult vaccine recipients of all ages, even those over 60 years of age, demonstrated a robust capacity for achieving hepatitis B seroprotection in response to the combined hepatitis A/hepatitis B vaccine. The role for vaccination in interrupting HBV transmission during an outbreak remains unclear, but concerns about age-related response to hepatitis B vaccine may be insufficient to justify foregoing vaccination of susceptible residents of ALFs.

This outbreak highlights the value of policies and practices that support an integrated outbreak response among public health practitioners, poison center staff, laboratorians, clinicians, law enforcement agents, community groups, and other agencies. Collaboration enabled implementation of effective control measures-including those outside the purview of the health department-and should be standard practice in future outbreaks involving illicit substances.