How the flu shot is determined each year

Canva Millions of people get the flu every year during flu season, which is primarily during the fall and winter months with December through February being the peak point. Infection with the influenza virus, commonly known as the flu virus, can lead to all manner of symptoms from fever and congestion to fatigue or respiratory issues. But while some people experience flu infection as little more than a “rough cold,” the flu is a potentially serious illness. Complications from the flu can lead to hospitalization or even death–especially for older people, very young children, and those with chronic health conditions like heart disease, asthma, or diabetes. The best way to reduce your risk of getting the flu is to get an annual flu shot. All flu vaccines available in the U.S. are quadrivalent, meaning they have been engineered to protect against four different strains of influenza. The Centers for Disease Control and Prevention recommends that, with few exceptions, anyone aged 6 months or older get vaccinated against the flu with either a direct injection vaccine or an attenuated vaccine, which is administered as a nasal spray. Stacker used information from the CDC, National Institute of Allergy and Infectious Diseases, and the World Health Organization to compile a list of things to know about the flu shot, including the different ways flu shots are manufactured and how the viral strains included in the shot are identified each year. You may also like: Over 45? Here’s how often you should be screened for these health conditions Why you need a flu shot