Clinical Update: The return of influenza season: What has changed?

November 1, 2006

The 2006-2007 influenza season is upon us. Influenza epidemics have been associated with an average of about 36,000 deaths per year in the United States from 1990 to 1999.1 In July of this year, the Advisory Committee on Immunization Practices (ACIP) updated its recommendations for the prevention and control of influenza.2

The 2006-2007 influenza season is upon us. Influenza epidemics have been associated with an average of about 36,000 deaths per year in the United States from 1990 to 1999.1 In July of this year, the Advisory Committee on Immunization Practices (ACIP) updated its recommendations for the prevention and control of influenza.2

Influenza vaccination continues to be the primary method for the prevention of this illness and its serious complications. In 2006, approximately 218.1 million persons in the United States will be included in one or more of the recommendation's target groups for immunization, summarized in Table 1. The 2006 recommendations include 6 principal changes or updates, summarized in Table 2.

As of July of this year, influenza vaccine manufacturers were projecting that about 100 million doses of influenza vaccine would be available in the United States for the 2006-2007 influenza season, an increase of approximately 16% from last season. The composition of this year's vaccine is based on the influenza A and B viruses that are expected to circulate in the United States during 2006-2007.

Both the inactivated influenza vaccine and the live, attenuated influenza vaccine (LAIV) are available; although each is effective, they differ in several respects.3 The ACIP indicates that although LAIV is more expensive than inactivated influenza vaccine, the price differential between them has decreased for the 2006-2007 season.

Of importance, as of February of this year, 6 states had enacted legislation banning the administration of vaccines that contain mercury. Thimerosal, a mercury-containing compound, is used in multidose vials of inactivated influenza vaccine to reduce the likelihood of bacterial contamination; vaccines that contain trace amounts of thimerosal have less than 1 µg of mercury per dose. Since mid-2001, manufactured vaccines regularly recommended for infants in the United States contain no thimerosal or only trace amounts. These laws may present a barrier to vaccination during this influenza season if the availability of doses of vaccines without thimerosal is inadequate.

Researchers have studied the effects of influenza vaccination on health care costs and productivity losses associated with influenza illness. These studies indicate that influenza vaccination of persons aged 65 years and older in the United States substantially reduces the number of hospitalizations and deaths and contributes to societal costs savings.4-6 Studies of adults younger than 65 years report that influenza vaccination reduces both direct medical costs and indirect costs from work absenteeism.7-12

Although vaccination is considered to be the linchpin in the approach to the prevention of influenza, antiviral medications are viewed as an important adjunct to administering the vaccine.13 The neuraminidase inhibitors zanam- ivir and oseltamivir have activity against both influenza A and B viruses; both drugs are approved for treatment of uncomplicated influenza virus infections. Oseltamivir is approved for chemoprophylaxis of influenza among persons aged 1 year and older. In March of this year, zanamivir was approved for chemoprophylaxis among children aged 5 years and older.

References:

REFERENCES


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