A Seasonal Viral Infection
Influenza, often referred to as the “flu,” is a contagious respiratory infection caused by a virus circulating each year from October to May. Although a very mild case of the flu might be mistaken for the common cold, many people have more severe symptoms beyond merely a sore throat and nasal congestion. Most people who contract influenza completely recover; however, it can result in serious illness, hospitalization, and even death. According to the CDC, 35.5 million people contracted the flu in the 2018-2019 season. Of those, hospitalization occurred in 490,000 people, and 34,200 people died. Older adults, very young children, pregnant women, and those with underlying medical conditions are at the highest risk of serious flu complications.
Symptoms Resemble the Common Cold
Influenza is spread from person to person through contact with tiny droplets expelled when an infected person talks or coughs. It can also spread by touching surfaces such as phones, desks, and keyboards with flu virus on them and then touching your eyes, nose, or mouth.
In addition to the sore throat, runny nose, and nasal congestion experienced with a common cold, a person with influenza can also have a fever, body aches, headache, fatigue, and cough. Young children with the flu may feel nauseous or have diarrhea. Symptoms from influenza develop more rapidly and are more severe than symptoms of the common cold.
Complications of influenza can be severe and include bronchitis, pneumonia, sinus or ear infections, and severe inflammation of the muscles, brain, or heart. Those with asthma or chronic obstructive pulmonary disease can experience flare-ups.
Treatment Involves Control of Symptoms
The main goal of treatment for influenza is to ease symptoms and speed recovery while avoiding complications. Antiviral medications are approved for the prevention and treatment of influenza. They reduce the severity of symptoms, shorten the period of illness, and help prevent complications. To be effective, treatment with antiviral medications must start within 48 hours of symptom onset. Common antiviral drugs include oral oseltamivir and balixavir marboxil, inhaled zanamivir, and IV peramivir. Antivirals work by preventing the release of virus particles from an infected cell. Balixavir marboxil works by preventing the replication of the virus itself.
Antibiotics are not effective against viruses like influenza or the common cold. Some who develop a bacterial infection along with influenza may be prescribed antibiotics to treat the coinfection.
Vaccination Provides Protection From Influenza
Prevention is the best way to avoid the symptoms, complications, and lost days of school or work due to influenza. It is recommended that everyone aged 6 months and older receive the flu vaccine each year. Consult with your physician first if you are allergic to chicken eggs, the vaccine itself, or have a history of Guillain-Barré syndrome (a paralytic reaction) after previous influenza vaccination.
It takes 2 to 4 weeks after vaccination to build effective immunity against the flu. Vaccines work by stimulating the production of antibodies to flu viruses. The viruses that cause the flu can change each year, so a new set of vaccines is formulated every year to offer specific protection during the upcoming flu season. There are two different types of flu vaccines, trivalent and quadrivalent. Current trivalent influenza vaccines include protection against three particular strains of the virus: one strain of influenza A (H3N2) and one strain of influenza B, as well as another strain of influenza A (H1N1), commonly known as the swine flu. The quadrivalent influenza vaccines include protection against an additional strain of influenza B.
Vaccines are administered by intramuscular injection or via nasal inhalation. Your doctor will choose a licensed, approved vaccine and dose based on your age and health status. The best time to get the flu vaccine is before the peak of the season in October. However, vaccination in January or February may still be effective in the prevention of influenza infection.
Credit to US Pharm. 2020;45(10):14.