US Pharm. 2020;45(1):13-14.

Seasonal Viral Infection

Influenza, often referred to as the flu, is a contagious viral infection that circulates year-round but is most common from October to May. The influenza virus is transmitted from person to person via droplets expressed when coughing, sneezing, or speaking. The droplets can be inhaled directly or picked up from objects such as phones, doorknobs, and keyboards. Symptoms begin to develop 1 to 4 days after exposure to the virus and usually last 7 to 10 days. The flu virus is constantly changing and evolving, with new strains emerging frequently. So, even if you have had the flu in the past, you are still vulnerable to different and new strains of the virus. 

Diagnosis and Complications

Symptoms of the flu can resemble the common cold, which is also caused by a virus. In addition to the sore throat, runny nose, and nasal congestion that is 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 flu may vomit or have diarrhea. Although any of these symptoms can accompany the common cold, people with influenza often have more severe symptoms. 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.

Treating Flu Symptoms

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 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.

Also available are prescription antiviral medications approved for the treatment of influenza that can reduce the severity of symptoms, shorten the period of illness, and help prevent complications. There are currently four approved antiviral medications: Rapivab (peramivir), Relenza (zanamivir), Tamiflu (oseltamivir phosphate, also available as generic), and Xofluza (baloxavir marboxil). Antiviral drugs may provide the most benefit for patients who initiate therapy within 48 hours of symptom onset, so a prompt visit to the doctor is necessary.

Prevention Through Vaccination

To prevent influenza, the CDC recommends everyone aged 6 months and older receive the influenza vaccine every season unless they are allergic to chicken eggs, the vaccination itself, or have a history of Guillain-Barré syndrome (a paralytic reaction) after previous influenza vaccination. Vaccination to prevent flu is particularly important for people who are at high risk of developing serious flu complications, such as those aged 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.

One should be vaccinated before the start of peak flu season, in October or November. Since the viruses that cause the flu can change each year, a different vaccine is formulated annually to offer specific protection during the upcoming flu season. Two types of vaccines are available: a trivalent vaccine that targets three strains of the flu virus, as well as a quadrivalent vaccine that targets four strains. Both are administered via intramuscular (into the muscle) injection.

It takes 2 to 4 weeks after vaccination to build effective immunity against the flu. If you need to be vaccinated for the seasonal flu or if you have any questions about influenza vaccination, speak with your local pharmacist who can help.

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