Why Do I Need A Flu Shot Every Year?
Each year, millions of Americans contract influenza, leading to anywhere from 200-500,000 hospitalizations and 18-50,000 deaths. Fortunately, while the flu is highly contagious—and dangerous to the immunocompromised—its severity can be significantly decreased through vaccination. In fact, many organizations, including Harvard University, require annual flu shots.
In this Q & A, we explain the importance of receiving a flu shot every year and why you cannot contract the flu via vaccination.
Why do you need a flu shot every year?
The simple answer is that the flu has multiple strains that can (and do) mutate. Each year we make an educated guess as to which of the four strains of influenza are going to dominate during flu season. Since flu starts in the southern hemisphere, those in the northern hemisphere look there to see which of the strains are causing the most illness or severe symptoms. We then try to make sure that our formula for that flu season has the right mix. Because of this, the flu vaccine does not give lifetime protection but about a season’s worth.
Now that people are cognizant of COVID-19 and its variants, they may have a better understanding of why we need an annual flu vaccine.
Who is at risk of a severe case of flu?
Like COVID, the flu is particularly dangerous for babies—who are unable to get vaccinated—as well as the pregnant, immunocompromised, and elderly.
Although some—like those who are pregnant—may be anxious about getting vaccinated, it is essential to be protected if you are at increased risk. A severe case of flu can develop into a bad case of pneumonia which can turn into a bacterial infection.
How do I know if I have the flu?
It can be difficult to determine the difference between the flu and other circulating respiratory illnesses, like the common cold and COVID-19, as symptoms often overlap.
If you have respiratory symptoms, wear a mask when around others and take an at-home antigen test to rule out COVID-19. Fortunately, like COVID-19, you can also be tested for flu, including at the Urgent Care department at Harvard University Health Services (HUHS).
Can I get the flu from the vaccine?
The influenza vaccine does not contain the live virus. So, you are not going to get the flu from the flu vaccine. Some vaccinated people may experience a sore arm and mild symptoms—such as a low-grade fever and chills—that should resolve within 24-48 hours. These symptoms are your body’s immune response to the flu vaccine as it builds protection from the illness. It is not the flu.
When is the flu vaccine available?
Flu season in the northern hemisphere typically begins in October—although it varies each year—and peak activity is apparent between December and February. The vaccine is typically available in late August or September.
HUHS hosts flu vaccine clinics for the Harvard community each year. Find the list of upcoming HUHS flu clinics on the HUHS website. Additionally, it is safe to get both the flu and COVID-19 vaccines at the same time. So, if you are eligible for a booster this fall, it is perfectly safe to schedule an appointment for both.