FLU NEWS SCAN: Impact of H1N1 antiviral guidance, risk factors in H5N1 clusters

Oct 20, 2011

Clinician heeded new antiviral guidance during pandemic
New guidelines during the 2009 H1N1 pandemic that encouraged antiviral treatment for all patients hospitalized with influenza boosted the use of the drugs, especially in pregnant women, researchers reported yesterday. The group based its findings, which appear in the Journal of Infectious Diseases, on a comparison of medical records during the four flu seasons that preceded the pandemic with those from about the first 8 months of the pandemic. Their data are from the US Center for Disease Control and Prevention's Emerging Infections Program, which conducts surveillance on patients hospitalized with lab-confirmed flu in 10 states. During the prepandemic seasons, 54% of patients hospitalized with flu received antiviral medication, which grew to 82% during the pandemic. Before the pandemic, only 22% of pregnant women hospitalized for flu received antivirals, a level that spiked to 86% during the pandemic. Clinicians also appeared to follow the revised recommendation to prescribe antivirals, even in patients beyond the 2-day symptom-onset period. That level increased from 43% to 79%. The researchers concluded that there is still room for improvement, given that all hospitalized patients with flu should receive antivirals. They suggested that the development of more accurate and timely flu diagnostic tests might increase antiviral use in these patients.
Oct 19 J Infect Dis abstract

Study finds larger households a risk in Indonesian H5N1 clusters
Cluster outbreaks of H5N1 avian influenza (AI) in Indonesia involved larger households and more close relatives compared with isolated cases, according to a statistical analysis published in Clinical Infectious Diseases. An international team of researchers analyzed data from 139 H5N1 outbreaks, of which 113 involved isolated cases and 26 were clusters. The outbreaks involved 177 total cases—159 laboratory confirmed and 18 probable. A cluster was defined as two or more cases associated with a specific setting, with disease onset within 2 weeks of each other. The average cluster size was 2.5 cases. The team used logistic regression to assess risk factors for the outbreaks and found that clusters involved larger households and more blood-related contacts, especially first-degree relatives, compared with isolated cases. Risk factors for secondary case infection were being from 5 to 17 years old or 18 to 30, having direct exposure to sources of H5N1 virus, and being a first-degree relative of an index case. In fact, siblings were five times more likely to contract secondary cases than were other contacts. The authors conclude, "The study adds evidence that AI H5N1 infection is influenced by, and may even depend on, host genetic susceptibility."
Oct 19 Clin Infect Dis abstract

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