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Pandemics attributable to different influenza A virus subtypes occurredat irregular intervals throughout the 20th century. Because the timingof a pandemic cannot be predicted, we must be prepared for such an outbreak.Although influenza is generally viewed as an illness with potentiallydeadly effects primarily for elderly persons, it can lead to significant morbidityand mortality in otherwise healthy infants and toddlers and in other highriskgroups.
Given the current vaccine shortage, what steps can I take to protectmy patients who are at risk for complications from influenza?
Pandemics attributable to different influenza A virus subtypes occurredat irregular intervals throughout the 20th century. Because the timingof a pandemic cannot be predicted, we must be prepared for such an outbreak.Although influenza is generally viewed as an illness with potentiallydeadly effects primarily for elderly persons, it can lead to significant morbidityand mortality in otherwise healthy infants and toddlers and in other high riskgroups.Approximately 185 million Americans are eligible for vaccination; lastyear, about 83 million were vaccinated. This year, however, more than halfof the vaccine supply was withheld or destroyed because of bacterial contaminationduring production. About 58 million doses of inactivated vaccineand 3 million doses of intranasal live vaccine will be available--enough forapproximately one third of the persons for whom the vaccine is usually targeted.Inadequate distribution and availability have been reported; rationingis certain.The CDC has issued a priority list of persons who should be vaccinated;this list includes those at highest risk for complications of influenza,such as severe illness, hospitalization, and death
Note that the intranasalvaccine is indicated only for healthy persons between the ages of 5and 49 years; it should be used primarily for health care workers or householdcontacts of infants younger than 6 months.The American Thoracic Society(ATS) recommends that wheneverpossible, physicians use theCDC guidelines to determine whichof their patients should be vaccinated.The ATS also suggests workingwith local and state public officialsconcerning specific patients' needsand vaccine availability. Additionalshipments of vaccine are expectedin the coming weeks. Therefore, itwill be necessary to develop a flexiblevaccine distribution plan thatevolves as vaccine availability shifts.
General preventive measures.
Warn patients to avoid crowds andanyone who is coughing or sneezing.Most infections result from in haled droplet nuclei, but some transmission occurs fromskin contact. Frequent hand washing and use of antibacterialtowelettes are effective protective measures.
These drugs are available for prophylaxisand treatment of influenza
For maximumefficacy, they must be administered within 48hours of symptom onset--and preferably within 30 to36 hours of confirmation of an influenza diagnosis. It isnot known whether these agents prevent influenza-relatedcomplications.The ion channel blockers amantadine and rimantadineare indicated for prophylaxis against influenza A inpersons older than 1 year. They can also be used to abortor shorten an attack of influenza A.The oral agent oseltamivir and the inhaled agentzanamivir inhibit the neuraminidase enzyme, which isnecessary for viral replication. Oseltamivir is indicatedfor prophylaxis of influenza A and B in persons 13 yearsand older and treatment of those 1 year and older.Zanamivir is indicated for the treatment of influenzaA and B in persons 7 years and older; it is not widelyused because it causes bronchospasm and wheezingin a significant number of patients. It is contraindicatedin persons with asthma or chronic obstructive pulmonarydisease, 2 chronic respiratory diseases for whichinfluenza vaccination is indicated.
Recent reports indicate that anintradermal influenza injection of 0.1 mg produced animmunologic response equivalent to the recommendeddosage of 0.5 mg given intramuscularly in persons aged18 to 40 years.
However, similar responses did notoccur in persons older than 60 years--ie, those at highestrisk.
These immunologic responses cannot beequated to protection against influenza, and thereforereduced dosages cannot be recommended as a meansof "stretching the supply."
Kenney RT, Frech SA, Muenz LR, et al. Dose sparing with intradermal injectionof influenza vaccine. Available at: http://www.nejm.org. Accessed November3, 2004.
Belshe RB, Newman FK, Cannon J, et al. Serum antibody responses afterintradermal vaccination against influenza. Available at: http://www.nejm.org. AccessedNovember 3, 2004.
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