This year, one strain of influenza A (H3N2) virus is being reported as the most common cause for the flu. This strain of virus has been particularly serious in the past, causing more hospitalizations and deaths than many other strains of the flu virus. Even though a H3N2 virus was used in the production of this year’s flu vaccine, the strain that is causing most of the infections is somewhat different than the type used in making the vaccine so it is not providing complete protection.
For most healthy individuals, the flu is an uncomfortable, but temporary illness. For certain groups of people including the elderly, chronically ill, and infants, the flu can be life threatening. With the knowledge that this year’s flu vaccine is not providing complete protection, this week, the Centers for Disease Control (CDC) released recommendations for the treatment of influenza. These recommendations apply primarily to the categories of people in whom influenza represents the most serious threat and pertains primarily to the use of anti-viral (neuraminidase inhibitor) medications.
In this year’s flu outbreaks, the CDC recommends that individuals who should receive anti-viral medication are:
- Any patient with flu who requires hospitalization
- Any patient with severe or complicated flu, including those who remain as outpatients but may have a complication such as pneumonia.
- Anyone who is at higher risk for flu complications including:
- Children younger than 2 years (although all children younger than 5 years are considered at higher risk for complications from influenza, the highest risk is for those younger than 2 years);
- Adults aged 65 years and older;
- Persons with chronic illnesses. This includes chronic lung diseases (asthma, emphysema), heart or vascular disease (except hypertension alone), chronic kidney disease, chronic liver disease (e.g. chronic hepatitis), blood disorders (e.g. sickle cell disease, leukemia, etc.) and metabolic disorders (including diabetes mellitus). Others include those with neurologic and neurodevelopment conditions (including disorders of the brain, spinal cord, peripheral nerve, and muscle such as cerebral palsy, epilepsy [seizure disorders], stroke, intellectual disability [mental retardation], moderate to severe developmental delay, muscular dystrophy, or spinal cord injury);
- Persons whose immune system is compromised, including that caused by medications (e.g. corticosteroids) or by HIV infection;
- Women who are pregnant or have recently delivered (within 2 weeks after delivery);
- Persons aged younger than 19 years who are receiving long-term aspirin therapy;
- American Indians/Alaska Natives;
- Persons who are morbidly obese (i.e., body-mass index is equal to or greater than 40); and
- Residents of nursing homes and other chronic-care facilities.
Three anti-viral medications have been approved by the U.S. Food and Drug Administration (FDA) for treating influenza during this season. These are: oseltamivir (Tamiflu®), zanamivir (Relenza®), and peramivir (Rapivab®). Oseltamivir is an oral medication that has been approved for treatment of the flu in individuals aged 2 weeks and older. Zanamivir is an inhaled medication approved for treatment of the flu in persons 7 years of age and older. Peramivir is given intravenously and used in persons aged 18 years and older. Anti-viral treatment is most beneficial when administered early in the illness, ideally within 48 hours of the onset of symptoms. The CDC advises that treatment in those groups that are at highest risk should begin even before laboratory confirmation of the infection is made.
In spite of being somewhat off the mark in regard to protection against the H3N2 strain of influenza A this year, the current vaccine does provide protection against other strains of the flu virus in this year’s outbreak. In those not yet immunized, there is still time to receive this protection. Recognizing the seriousness of the predominant flu strain this season, those who are at high-risk for complications should additionally seek treatment with an anti-viral medication if the flu is suspected.
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