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Influenza

By Staff

11/20/2012

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US Pharm. 2012;37(11):17-18.

A Seasonal Viral Infection

Influenza, often referred to as the “flu,” is a contagious viral infection that circulates each year during the period from October to May. Although a mild case of the flu might be mistaken for the common cold, most cases have more severe symptoms beyond simply a sore throat and nasal congestion. Influenza symptoms usually last 7 to 10 days and include fever, chills, body aches, headache, cough, and fatigue. Bed rest and plenty of fluids are general treatment recommendations, along with OTC medications aimed at relieving symptoms.

A vaccine is available to help protect against influenza by stimulating the production of antibodies to flu viruses. The viruses that cause the flu can change each year, so a vaccine is formulated every year to offer specific protection during the upcoming flu season. The current trivalent influenza vaccine includes protection against three specific strains of viruses: one strain of influenza A (H3N2), one strain of influenza B, and another strain of influenza A (H1N1), commonly known as “swine flu.”

Everyone 6 months of age and older should receive the flu vaccine each year as soon as it is available. It takes 2 to 4 weeks after vaccination to build effective immunity against the flu. It is especially important for certain groups of people to receive the flu vaccine because they are at higher risk for developing serious complications. These groups include people 65 years and older; those with chronic diseases such as asthma, lung disease, or diabetes; pregnant women or those who may become pregnant or breastfeed during the flu season; and those who take care of people at high risk for serious complications from the flu.

The Flu Vaccine Is Recommended for Those Aged 6 Months and Older

Although influenza is considered a nuisance by most, thousands of people in the United States die each year from the flu or related complications. Most of those deaths are in people 65 years and older, but even younger, healthier people can become seriously ill from the seasonal flu. For these reasons, everyone 6 months of age and older should receive the flu vaccine each year, unless they are allergic to chicken eggs or the vaccination itself, or have a history of Guillain-Barré syndrome (a paralytic reaction) after a previous influenza vaccination.

Getting Vaccinated to Prevent the Flu

The flu vaccine is made from the killed virus strains most likely to be circulating in the upcoming flu season. There are four methods of administering the flu vaccine, with specific guidelines for their use in certain patient groups. These include the standard intramuscular flu shot, a high-dose shot for people 65 years and older, and an intradermal shot using a much smaller needle for people ages 18 to 64 years. There is also a nasal spray formulation made from live but weakened flu virus strains that do not cause the flu but result in immunity against the viruses included in the vaccine. The nasal formulation is approved only for healthy, nonpregnant people ages 2 to 49 years who do not have asthma or a history of wheezing. If you need to be vaccinated for the seasonal flu, many pharmacies provide this service.

Treatment of Flu Symptoms

Symptoms of the flu can resemble the common cold, which is also caused by viruses. In addition to the sore throat, runny nose, and nasal congestion typically seen with a cold, a person suffering from influenza can have a fever or feel feverish, with body aches, headache, fatigue, and a cough. Young children with the flu may feel nauseated or have diarrhea. Although any of these symptoms can accompany the common cold, people with influenza are more likely to have more symptoms and feel more ill than those with a cold.

The goal of treatment is to ease symptoms and speed recovery while avoiding complications. General recommendations include bed rest and drinking plenty of fluids. Acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs such as ibuprofen or naproxen) can relieve fever, headache, and body aches. Decongestants, cough suppressants, and expectorants are useful for cough and congestion. Many nonprescription cold or flu symptom relievers contain multiple drugs, so it is important to read the labels to avoid taking more than the recommended dose of the same medication in two or more products. There are also antiviral medications approved for prevention and/or treatment of influenza that reduce the severity of symptoms, shorten the period of illness, and help prevent complications. Antivirals carry a warning that they are not to be used as a substitute for the vaccine, as they may not be protective against all influenza viruses.

Complications likely to develop from the flu include bronchitis, pneumonia, and sinus or ear infections. These complications are often caused by bacteria and should be treated with an antibiotic. If symptoms of influenza begin to improve and then worsen, a bacterial infection may be the cause and the patient should seek medical care for evaluation.

To comment on this article, contact rdavidson@uspharmacist.com.

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