Why Is Influenza So Difficult to Prevent and Treat?

Tough Questions About Influenza: Prevention and Treatment

When the Centers for Disease Control and Prevention (CDC) recently announced that this season's influenza vaccine was only 23% effective against the current predominant A strain (H3N2),^[1] many people were unsurprised. Infectious diseases specialists were already aware that most of the A (H3N2) viruses currently circulating had drifted (mutated antigenically and genetically) from the A component selected for inclusion in the 2014-2015 seasonal vaccine.^[2] Furthermore, for many members of the public who had been skeptical about the usefulness of any influenza vaccine, the announcement appeared to confirm their view that there was no benefit to being vaccinated. (The vaccine is even less effective in persons older than 50 years).

Despite the limited protection provided by this season's influenza vaccine, the CDC repeated its recommendation for vaccination of everyone aged ≥ 6 months. Because influenza was already widespread and the season is expected to be severe, the CDC also reiterated its earlier recommendation that as an adjunct to vaccination, all hospitalized patients and outpatients at high risk for serious influenza complications should be treated with an antiviral medication (neuraminidase inhibitor) as soon as possible after influenza is suspected, without waiting for laboratory confirmation of the diagnosis.^[1,3] Antiviral treatment is also recommended as an option in non–high-risk individuals with suspected or confirmed influenza.

Regardless of the CDC's recommendations, many in the healthcare community have expressed doubts about the value of the current influenza vaccination program, given that the predominant strain is not included in the vaccine, and concerns have been raised about vaccine safety. Moreover, clinicians have been presented with conflicting evidence about the efficacy of antiviral drugs, and debate continues as to whether benefits of these agents outweigh the associated costs and risks.

To address these issues, Medscape spoke with two leaders in the field of influenza prevention and control to hear their views about the CDC's current recommendations; why the current approach appears to be so ineffective; and, of greatest importance, what can be done to improve the situation and prevent the spread of influenza, and possibly even a new pandemic, in the future. Andrew T. Pavia, MD, is George and Esther Gross Presidential Professor and chief of the Division of Pediatric Infectious Diseases at the University of Utah School of Medicine in Salt Lake City, Utah, and Gregory A. Poland, MD, is professor of medicine and director of the Vaccine Research Group, Mayo Clinic, Rochester, Minnesota. Both have expertise in vaccines and public health and have served on federal and state advisory committees on vaccine policy, biodefense, and pandemic influenza preparedness.

Cite this: Why Is Influenza So Difficult to Prevent and Treat? - Medscape - Jan 23, 2015.

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