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SPECIAL ARTICLES: Guidelines Section


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Infectious Diseases in Clinical Practice: March 2002 - Volume 11 - Issue 3 - p 159-160
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[CDC MMWR 2002;51:RR-3]

This is the review of influenza with the following points:

Clinical Features:

The incubation period averages two days with a range of 1–4 days. The infection can be transmitted from one day before symptoms until five days after onset of symptoms. Severely immunosuppressed patients can shed virus for weeks. The sensitivity of the clinical diagnosis based largely on symptoms of cough and fever in an epidemic is 60–80%.

Hospitalizations and Death:

The average is 114,000 influenza-related excess hospitalizations/year; the highest is for infections involving influenza A (H3N2), which average 142,000 hospitalizations/year. Excess deaths have occurred in 19 of the last 23 influenza epidemics with the range of 30–150 deaths/100,000 persons aged 65 or older.

Vaccine for 2002–3:

The trivalent vaccine for next season includes A/Moscow/10/99 (H3N2)-like, A/New Caledonia/20/99 (H1N1)-like and B/Hong Kong/330/2001-like antigens.

Vaccine Effectiveness:

When the match is good, the protection is 70–90% for persons under 65 years (JAMA 1999;281:908; JAMA 2000;284:1655; Vaccine 2000;18:957). Responses are reduced in older persons and those with chronic disease (CID 1996;22:295). For elderly persons in nursing homes, the most important benefit is a 50–60% reduction in rates of hospitalization or pneumonia and an 80% reduction in death (JAMA 1985;253:1136).

Cost Effectiveness:

Reports show vaccination in persons <65 years results in reduced physician visits, reduced work loss, and reduced antibiotic use (NEJM 1995;333:889; JAMA 2000;284:1655). Net cost savings for vaccinations of persons >65 years showed cost benefit of $23–256/QALY.

Coverage Levels:

For persons >65 years, the vaccination rate has increased from 33% in 1989 to 66% in 1999. For residents of nursing homes, the rate is 64%–82%. However, for persons under 50 years with high-risk medical conditions, the rate is only 25%.

Recommendations for Vaccine:

  1. Persons at increased risk for complications
    • Age > 65 years
    • Residents of chronic care facilities
    • Chronic pulmonary or cardiovascular disease
    • Chronic metabolic disease (diabetes), renal failure, hemoglobinopathy or immunosuppression (meds or HIV)
    • Women in the second or third trimester of pregnancy during the influenza season.
  2. Persons who can transmit influenza to high-risk persons
    • Doctors and nurses, etc. in medical practice
    • Employees of chronic care facilities
    • Persons who provide home care for groups at risk.
  3. Any person who wants the vaccine should get it.
  4. Travelers: Influenza can occur in the tropics throughout the year and in the southern hemisphere, the majority of influenza activity is during April–September. Persons at high risk should be vaccinated if not vaccinated during the preceding fall or winter if they (1) travel to the tropics, (2) travel with a tourist group at any time of year, or (3) travel to the southern hemisphere during April–September.

Vaccination Season:

October–November. Peak antibody occurs at two weeks. Antiviral Agents:

  • Efficacy: There is approximately an average one-day reduction in the duration of uncomplicated influenza when any of the four agents are given within two days of onset of symptoms. There are no studies showing benefit in preventing serious influenzarelated complications and most studies have been done with uncomplicated influenza. There are also no data for these drugs in persons with severe immunodeficiency.
  • Indications for Prophylaxis:
    1. Persons at high risk who are unvaccinated after a community outbreak □prophylaxis should continue after vaccination for two weeks.
    2. Consider prophylaxis for persons who provide care to high-risk patients until two weeks after vaccination in the presence of an outbreak.
    3. If an outbreak is caused by a variant strain of influenza not controlled by the vaccine, prophylaxis should be considered for high-risk persons and those who care for them. The duration is arbitrary.
    4. Persons with immunodeficiency may be given prophylaxis, but there are no published data concerning benefit and “such persons should be monitored closely.”
    5. Persons with contraindications to vaccine who have high risk should be considered for prolonged prophylaxis.
  • Doses: The doses are provided in Table 6.
  • T1-14
    TABLE 6
© 2002 Lippincott Williams & Wilkins, Inc.