The major changes in the influenza guidelines as applied to adults are the following:
Optimal time to vaccinate: The optimal time is October and November, but there have been distribution delays in the past that have led to preferential vaccination for high-risk patients during October with others to be vaccinated in November. The high risk group includes persons >50 years or 6-23 months, persons 2-49 years with high risk medical conditions, children <9 years receiving the initial vaccine, health care workers, and household contacts of persons at high risk.
The 2003-04 trivalent inactivated vaccine includes A/Moscow/10/99 (H3N2), A/New Caledonia/20/99 (H1N1) and B/Hong Kong/330/2001.
The US market will have vaccine available from 2 suppliers in 2003-04 compared to 3 in 2002-03.
Comment: The reduction in suppliers represents the withdrawal of Wyeth, which is pursuing the intranasal influenza vaccine "Flu Mist" with Med Immune. The FDA approved this vaccine June 17, 2003, but it is not mentioned in the CDC guidelines, presumably due to timing. The Flu Mist indication is for healthy persons aged 5-49 years, the price is $46 per dose, and the distribution system will include administration in pharmacies.[33,34]
Cooper NJ, Sutton AJ, Abrams KR, Wailoo A, Turner D, Nicholson KG. Effectiveness of neuraminidase inhibitors in treatment and prevention of influenza A and B: systematic review and meta-analyses of randomized controlled trials. BMJ. 2003;326:1235. Abstract This study was commissioned by the National Health Service to determine the effectiveness of neuraminidase inhibitors for the treatment and prevention of influenza caused by influenza A and influenza B. The analysis is unique for consideration of 3 distinct populations: children, healthy adults, and high-risk adults. High risk was defined as age ≥ 65 years or a chronic medical condition such as chronic heart or lung disease. For treatment, the end point was the time to relief of symptoms and the number of cases requiring antibiotics. Studies that address the reduction in antibiotics were limited to 2 studies of zanamivir, which showed a 29% relative reduction, and 1 study of oseltamivir, which showed a 43% reduction. With regard to treatment, both drugs successfully reduced symptoms by an average of 1-2 days in each of the 3 patient categories. For prevention, the drugs were 69% to 92% effective in the various populations reviewed. These data are summarized in Tables Table 18 and Table 19 .
The authors conclude that randomized trials demonstrate efficacy for oseltamivir and zanamivir for the treatment and prevention of influenza.
Comment: It should be emphasized that the data provided above for treatment are restricted to patients who received treatment within 48 hours of the onset of symptoms and restricted to those with an established infection involving influenza. There was a disappointing lack of evidence regarding these drugs for preventing influenza in children and in elderly people in residential care. In the accompanying commentary, Lucy Hansen from the University of Edinburgh commented that "it is difficult to see what important new information about the treatment of flu this meta-analysis offers."
Medscape Infectious Diseases. 2003;5(2) © 2003 Medscape
Cite this: July 15, 2003 - Medscape - Jul 24, 2003.