Two-dose varicella vaccine effectiveness and rash severity in outbreaks of varicella among public school students.

BACKGROUND: Universal 2-dose varicella vaccination was recommended in 2006 to further reduce varicella disease burden. This study examined 2-dose varicella vaccine effectiveness (VE) and rash severity in the setting of school-associated varicella outbreaks. METHODS: A case control study was conducted from January 2010 to May 2011 in all West Virginia public schools. Clinically diagnosed cases from varicella outbreaks were matched with classmate controls. Vaccination information was collected from school, health department and healthcare provider immunization information systems. RESULTS: Among the 133 cases and 365 controls enrolled, VE against all varicella was 83.2% [95% confidence interval (CI): 69.2%-90.8%] for 1-dose of varicella vaccine and 93.9% (95% CI: 86.9%-97.1%) for 2-dose; the incremental VE (2-dose vs. 1-dose) was 63.6% (95% CI: 32.6%-80.3%). In preventing moderate/severe varicella, 1-dose varicella vaccine was 88.2% (95% CI: 72.7%- 94.9%) effective, and 2-dose vaccination was 97.5% (95% CI: 91.6%-99.2%) effective, with the incremental VE of 78.6% (95% CI: 40.9%-92.3%). One-dose VE declined along with time since vaccination (VE = 93.0%, 88.0% and 81.8% in <5, 5-9 and ≥ 10 years after vaccination, P = 0.001 for trend). Both 1- and 2-dose breakthrough cases had milder rash than unvaccinated cases (<50 lesion: 24.6%, 49.1% and 70.0% in unvaccinated, 1-dose and 2-dose cases, P < 0.001), and no severe disease was found in 2-dose cases. CONCLUSIONS: Two-dose varicella vaccination is highly effective and confers higher protection than a 1-dose regimen. High 2-dose varicella vaccination coverage should maximize the benefits of the varicella vaccination program and further reduce varicella disease burden in the United States.

Outbreak of Tsukamurella species bloodstream infection among patients at an oncology clinic, West Virginia, 2011-2012.

OBJECTIVE: To determine the source and identify control measures of an outbreak of Tsukamurella species bloodstream infections at an outpatient oncology facility. DESIGN: Epidemiologic investigation of the outbreak with a case-control study. METHODS: A case was an infection in which Tsukamurella species was isolated from a blood or catheter tip culture during the period January 2011 through June 2012 from a patient of the oncology clinic. Laboratory records of area hospitals and patient charts were reviewed. A case-control study was conducted among clinic patients to identify risk factors for Tsukamurella species bloodstream infection. Clinic staff were interviewed, and infection control practices were assessed. RESULTS: Fifteen cases of Tsukamurella (Tsukamurella pulmonis or Tsukamurella tyrosinosolvens) bloodstream infection were identified, all in patients with underlying malignancy and indwelling central lines. The median age of case patients was 68 years; 47% were male. The only significant risk factor for infection was receipt of saline flush from the clinic during the period September-October 2011 (P = .03), when the clinic had been preparing saline flush from a common-source bag of saline. Other infection control deficiencies that were identified at the clinic included suboptimal procedures for central line access and preparation of chemotherapy. CONCLUSION: Although multiple infection control lapses were identified, the outbreak was likely caused by improper preparation of saline flush syringes by the clinic. The outbreak demonstrates that bloodstream infections among oncology patients can result from improper infection control practices and highlights the critical need for increased attention to and oversight of infection control in outpatient oncology settings.

Dual resistance to adamantanes and oseltamivir among seasonal influenza A(H1N1) viruses: 2008-2010.

Two distinct genetic clades of seasonal influenza A(H1N1) viruses have cocirculated in the recent seasons: clade 2B oseltamivir-resistant and adamantane-susceptible viruses, and clade 2C viruses that are resistant to adamantanes and susceptible to oseltamivir. We tested seasonal influenza A(H1N1) viruses collected in 2008-2010 from the United States and globally for resistance to antivirals approved by the Food and Drug Administration. We report 28 viruses with both adamantane and oseltamivir (dual) resistance from 5 countries belonging to 4 distinct genotypes. Because of limited options for antiviral treatment, emergence of dual-resistant influenza viruses poses a public health concern, and their circulation needs to be closely monitored.

Health effects associated with indoor swimming pools: a suspected toxic chloramine exposure.

OBJECTIVES: A cohort and environmental study tested the hypothesis that suspected exposure to chloramines (by-products of chlorine for disinfection and ammonia from human sources) from a hotel's indoor swimming pool was associated with an outbreak among children who had attended a party at the pool. STUDY DESIGN: Retrospective cohort study. METHODS: A case was defined as any hotel guest/visitor on 5-6 October 2002 who experienced three or more symptoms typical of chloramine exposure on either day after visiting the hotel. A cohort study and an environmental assessment were performed to determine the association between pool exposure and illness. RESULTS: Of 128 individuals interviewed, 32 met the case definition. Common symptoms among case patients were cough (84%), eye irritation (78%) and rash (34%). Illness was associated with entering the pool area [odds ratio (OR) 19.9; 95% confidence interval (CI) 2.3-172], but more strongly with swimming (OR 72.0; 95% CI 9.1-568). Pool chloramine levels on 6 October 2002 were > or = 0.7ppm (optimal level=0ppm; state maximum=0.5ppm). The pool operator lacked formal training in pool maintenance. CONCLUSIONS: High chloramine levels may have caused illness in individuals who were either in or near the pool. This outbreak underscores the need for regular pool maintenance, improved air quality, education and certification for all operators of public and semipublic pools, and education about healthy swimming practices.