CDC Advises Ramping Up Antiviral Use for Flu
Evidence suggesting that this year's flu vaccine missed the mark has caused the CDC to turn to other treatment strategies.
This season's influenza virus strain is causing increasing hospitalizations and further complications. More concerning is the fact that approximately two-thirds of the H3N2 viruses tested by the US Centers for Disease Control and Prevention (CDC) are antigenically or genetically different from the H3N2 vaccine virus. In other words, this year’s flu vaccine isn’t so great.
The concerning influenza update was followed by strong CDC recommendations for ramping up use of antiviral medications to treat the flu. However, there is controversy regarding the evidence supporting the use of antiviral medications like oseltamivir (Tamiflu). Despite the strong evidence of a systematic review, the CDC is favoring observational data that included hospitalized patients.
The observational data cited in the CDC report looked back at patients who were hospitalized due to influenza, particularly H1N1 strains1-3, pregnant patients with H1N14, and patients from the 2005-2006 influenza season in Canada.7 This observational data found links between oseltamivir initiated 4 and 5 days after onset of patients hospitalized with suspected or confirmed influenza and lower risk for severe outcomes, including death.
However, numerous limitations, including immunization status, selection bias, and differences in comorbidities, cloud the results. Nevertheless, the CDC has used this data to justify its recommendation to start oseltamivir, inhaled zanamivir, or intravenous peramivir as early as possible in patients hospitalized for confirmed or suspected influenza.
As the recommendations stand currently, there will likely be further emphasis on identification of influenza early in the course of a patient's hospitalization, as well as an increasing use of antiviral medication that is associated with, yet not reliably proven, to improve flu outcomes.
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2. Lee N, Choi KW, Chan PK, et al. Outcomes of adults hospitalised with severe influenza. Thorax. 2010 Jun;65(6):510-5.
3. Lee EH, Wu C, Lee EU, et al. Fatalities associated with the 2009 H1N1 influenza A virus in New York City. Clin Infect Dis. 2010 Jun 1;50(11):1498-504.
4. Siston AM, Rasmussen SA, Honein MA, et al. Pandemic 2009 influenza A(H1N1) virus illness among pregnant women in the United States. JAMA. 2010 Apr 21;303(15):1517-25.
5. McGeer A, Green KA, Plevneshi A, et al. Antiviral therapy and outcomes of influenza requiring hospitalization in Ontario, Canada. Clin Infect Dis. 2007 Dec 15;45(12):1568-75.