Flu season is here.
The contagious respiratory illness caused by viruses that infect the nose, throat and lungs can cause mild to severe illness and at times may lead to death. People of every age -; including people in good health -; are at risk for flu.
Approximately 970,000 Americans were hospitalized due to the flu in 2014, and more than 40 million were affected by flu-related illnesses, according to the Centers for Disease Control and Prevention.
Although a majority of hospitalizations and deaths occur in people 65 years and older, even healthy young children and younger adults can have severe disease or even die from influenza. Nearly 100 deaths from influenza among children are reported each year to the Centers for Disease Control and Prevention.
These data, say UAB experts, are reason enough for Americans to receive their yearly influenza vaccine.
The most common symptoms of the flu are fever, chills, fatigue, muscle aches, stuffy or runny nose, and sore throat, and symptoms typically last a week. A wide range of complications can be caused by influenza virus infection of the upper and lower respiratory tracts. Complications of flu can include bacterial pneumonia, ear infections, sinus infections, dehydration and worsening of chronic medical conditions, such as congestive heart failure, asthma or diabetes.
Forecasting flu season
Recent reports show that Australia has seen its worst flu season on record. Kevin Harrod, Ph.D., the Benjamin Monroe Carraway Endowed Chair and professor in the UAB Department of Anesthesiology and Perioperative Medicine, says what happens in the southern hemisphere is usually indicative of what type of flu season will occur in the northern hemisphere.
"These data tell us that we should see a worse than average flu season," Harrod said. "But, with all things influenza, there's a lot we don't know."
Harrod says this year's vaccines are combating the H3N2 strain and B strains of influenza. He added that H3N2 viruses cause worse disease in the elderly and young children, and that they are associated with a high hospitalization rate.
With all the knowledge and scientific research about influenza, Harrod says it is extremely difficult to perfectly forecast which strains are used to create vaccines.
"There are always a few strains circulating that aren't predominant, but can become predominant -; especially in populations of high immunization," he said. "So, it's difficult for public health officials to predict which strains will circulate. For that reason, not every vaccine is a perfect match."
Vaccines for everyone
In his lab, Harrod -; who has been studying influenza and other respiratory viruses for 20 years -; and his team research the effectiveness and development of novel antivirals against influenza. Because it is ever-changing, scientists are always looking for new and better ways to fight the severity and frequency of influenza.
Harrod says the best way to prevent flu from spreading and becoming more serious is by getting vaccinated.
"While getting the flu shot may not keep you from getting the flu, it will limit the severity and duration of the illness, and provide you with some protection against future infections in subsequent seasons," Harrod said. "Even in years when the flu vaccine is a 'bad match,' there is partial protection because one's immune system can make antibodies that still recognize and bind to the influenza virus even when new strains emerge unexpectedly."
Leah Leisch, M.D., assistant professor in the UAB Division of General Internal Medicine, says it is imperative everyone receives influenza vaccines because any flu vaccine can offer some protection against the virus.
"The CDC recommends all people ages 6 months and above -; including pregnant women -;receive an annual flu vaccination," Leisch said. "It is especially important for people at high risk for flu-related complications. This includes, but is not limited to, pregnant women, children younger than 5, adults older than 65 and people with certain medical conditions. The flu vaccine is not recommended for infants less than 6 months old."
Harrod says the CDC's Advisory Committee on Immunization Practices does not recommend the use of the live attenuated influenza vaccine, also known as the "nasal spray" flu vaccine, in the 2017-2018 influenza season.
The aftermath of flu
Once someone is infected with the virus, Leisch notes, there are two recommended courses of treatment.
"During flu season, if you experience flu-like symptoms, it is wise to let your doctor know within 24 to 48 hours of when the symptoms began," she said. "However, your doctor may not prescribe any medications, as most -; otherwise healthy -; adults under age 65 do not require prescription medication for flu."
In fact, Leisch says, for most people, the best therapy is to stay at home -; away from others -; and get plenty of rest and fluids. Young children, adults older than 65 and adults with certain medical problems may require treatment with an anti-viral medication to help prevent flu-related complications.
The other recommended course of treatment is with anti-viral medication.
"These medications are good at preventing complications of flu and shortening the duration of flu by one or two days," Leisch said. "However, they will not make the symptoms go away immediately."
She added that most healthy adults under age 65 do not require prescription medication for flu.