In March 2018, the US Department of Defense (DOD) added the smallpox vaccination, using ACAM2000, to its routine immunizations, increasing the number of persons receiving the vaccine. The following month, Fort Hood reported a cluster of 5 myopericarditis cases. The Centers for Disease Control and Prevention and the DOD launched an investigation.

The investigation consisted of a review of medical records, establishment of case definitions, causality assessment, patient interviews, and active surveillance. A 2-sided exact rate ratio test was used to compare myopericarditis incidence rates.

This investigation identified 4 cases of probable myopericarditis and 1 case of suspected myopericarditis. No alternative etiology was identified as a cause. No additional cases were identified. There was no statistically significant difference in incidence rates between the observed cluster (5.23 per 1000 vaccinated individuals, 95% CI: 1.7–12.2) and the ACAM2000 clinical trial outcomes for symptomatic persons, which was 2.29 per 1000 vaccinated individuals (95% CI: 0.3–8.3).

Vaccination with ACAM2000 is the presumptive cause of this cluster. Caution should be exercised before considering vaccination campaigns for smallpox given the clinical morbidity and costs incurred by a case of myopericarditis. Risk of myopericarditis should be carefully weighed with risk of exposure to smallpox.

To describe a Klebsiella pneumoniae carbapenemase (KPC)–producing carbapenem-resistant Enterobacteriaceae (CRE) outbreak and interventions to prevent transmission.

Epidemiologic investigation of a CRE outbreak among patients at a long-term acute care hospital (LTACH).

Microbiology records at LTACH A from March 2009 through February 2011 were reviewed to identify CRE transmission cases and cases admitted with CRE. CRE bacteremia episodes were identified during March 2009–July 2011. Biweekly CRE prevalence surveys were conducted during July 2010–July 2011, and interventions to prevent transmission were implemented, including education and auditin? of staff and isolation and cohorting of CRE patients with dedicated nursing staff and shared medical equipment. Trends were evaluated using weighted linear or Poisson regression. CRE transmission cases were included in a case-control study to evaluate risk factors for acquisition. A real-time polymerase chain reaction assay was used to detect the blaKPC gene, and pulsed-field gel electrophoresis was performed to assess the genetic relatedness of isolates.

Ninety-nine CRE transmission cases, 16 admission cases (from 7 acute care hospitals), and 29 CRE bacteremia episodes were identified. Significant reductions were observed in CRE prevalence (49% vs 8%), percentage of patients screened with newly detected CRE (44% vs 0%), and CRE bacteremia episodes (2.5 vs 0.0 per 1,000 patient-days). Cases were more likely to have received β-lactams, have diabetes, and require mechanical ventilation. All tested isolates were KPC-producing K. pneumoniae, and nearly all isolates were genetically related.

CRE transmission can be reduced in LTACHs through surveillance testing and targeted interventions. Sustainable reductions within and across healthcare facilities may require a regional public health approach.

Infect Control Hosp Epidemiol 2012;33(10):984-992