Assessment of vaccine exemptions among Wyoming school children, 2009 and 2011.

During 2010-2011, varicella vaccination was an added requirement for school entrance in Wyoming. Vaccination exemption rates were compared during the 2009-2010 and 2011-2012 school years, and impacts of implementing a new childhood vaccine requirement were evaluated. All public schools, grades K-12, were required to report vaccination status of enrolled children for the 2009-2010 and 2011-2012 school years to the Wyoming Department of Health. Exemption data were analyzed by exemption category, vaccine, county, grade, and rurality. The proportion of children exempt for ≥ 1 vaccine increased from 1.2% (1,035/87,398) during the 2009-2010 school year to 1.9% (1,678/89,476) during 2011-2012. In 2011, exemptions were lowest (1.5%) in urban areas and highest (2.6%) in the most rural areas, and varicella vaccine exemptions represented 67.1% (294/438) of single vaccination exemptions. Implementation of a new vaccination requirement for school admission led to an increased exemption rate across Wyoming.

Infections with oseltamivir-resistant influenza A(H1N1) virus in the United States.

CONTEXT: During the 2007-2008 influenza season, oseltamivir resistance among influenza A(H1N1) viruses increased significantly for the first time worldwide. Early surveillance data suggest that the prevalence of oseltamivir resistance among A(H1N1) viruses will most likely be higher during the 2008-2009 season. OBJECTIVES: To describe patients infected with oseltamivir-resistant influenza A(H1N1) virus and to determine whether there were any differences between these patients and patients infected with oseltamivir-susceptible A(H1N1) virus in demographic or epidemiological characteristics, clinical symptoms, severity of illness, or clinical outcomes. DESIGN, SETTING, AND PATIENTS: Influenza A(H1N1) viruses that were identified and submitted to the Centers for Disease Control and Prevention by US public health laboratories between September 30, 2007, and May 17, 2008, and between September 28, 2008, and February 19, 2009, were tested as part of ongoing surveillance. Oseltamivir resistance was determined by neuraminidase inhibition assay and pyrosequencing analysis. Information was collected using a standardized case form from patients with oseltamivir-resistant A(H1N1) infections and a comparison group of patients with oseltamivir-susceptible A(H1N1) infections during 2007-2008. MAIN OUTCOME MEASURES: Demographic and epidemiological information as well as clinical information, including symptoms, severity of illness, and clinical outcomes. RESULTS: During the 2007-2008 season, influenza A(H1N1) accounted for an estimated 19% of circulating influenza viruses in the United States. Among 1155 influenza A(H1N1) viruses tested from 45 states, 142 (12.3%) from 24 states were resistant to oseltamivir. Data were available for 99 oseltamivir-resistant cases and 182 oseltamivir-susceptible cases from this period. Among resistant cases, median age was 19 years (range, 1 month to 62 years), 5 patients (5%) were hospitalized, and 4 patients (4%) died. None reported oseltamivir exposure before influenza diagnostic sample collection. No significant differences were found between cases of oseltamivir-resistant and oseltamivir-susceptible influenza in demographic characteristics, underlying medical illness, or clinical symptoms. Preliminary data from the 2008-2009 influenza season identified resistance to oseltamivir among 264 of 268 influenza A(H1N1) viruses (98.5%) tested. CONCLUSIONS: Oseltamivir-resistant A(H1N1) viruses circulated widely in the United States during the 2007-2008 influenza season, appeared to be unrelated to oseltamivir use, and appeared to cause illness similar to oseltamivir-susceptible A(H1N1) viruses. Circulation of oseltamivir-resistant A(H1N1) viruses will continue, with a higher prevalence of resistance, during the 2008-2009 season.