How the Flu Vaccine Works

The flu shot helps your immune system prepare for influenza by exposing it to inactive (killed) virus components or a single viral protein. This allows your body to create antibodies that recognize and fight the flu if you’re exposed later.

It typically takes 10–14 days after vaccination for full immunity to develop.

Each year’s vaccine is updated based on global surveillance. The World Health Organization (WHO) evaluates which strains are most likely to circulate and guides vaccine formulation accordingly.

Most flu vaccines protect against multiple strains, commonly including:

• Influenza A – the most likely to mutate and cause widespread outbreaks
• Influenza B – often affects children more than adults
• Influenza C – generally milder and similar to a common cold

Because flu viruses change from year to year, annual vaccination is essential.

Flu Shot Myths—Debunked

Myth #1: The flu shot can give you the flu

False. The flu vaccine does not contain live virus and cannot cause influenza. Some people may feel mildly achy or tired after vaccination, which is a sign the immune system is responding—not an infection.

Myth #2: The flu shot has serious side effects

Serious reactions are extremely rare. The CDC reports that hundreds of millions of flu vaccines have been safely administered over decades. Mild side effects may include:

• Soreness or redness at the injection site
• Headache
• Low-grade fever
• Muscle aches

These symptoms typically resolve within a day or two.

Myth #3: I’m young and healthy—I don’t need it

Even healthy adults can get very sick from the flu and even die. During the 2017–2018 flu season, nearly 3,000 people ages 18–49 died from influenza in America. The vaccination also reduces the risk of spreading the virus to infants, older adults, and immunocompromised individuals.

Myth #4: I got a flu shot last year, so I’m covered

Protection fades over time, and flu strains change annually. You need a flu shot every year to stay protected against the current strains.

Myth #5: Pregnant women shouldn’t get the flu shot

False. Pregnant women are at higher risk for flu complications. Vaccination reduces the risk of being hospitalized with flu by an average of 40% and provides protection to newborns when they are too young to get vaccinated.

Flu Shot FAQs

Can I still get the flu after vaccination?

Yes, but illness is usually less severe. Vaccination significantly lowers the risk of hospitalization, complications, and death.

When is the best time to get a flu shot?

September and October are ideal in New England, but it’s never too late—vaccination remains beneficial throughout flu season.

Are flu shots safe for children?

Yes. Everyone 6 months and older should receive a flu vaccine unless advised otherwise by a medical provider.

Why does flu season last so long?

Flu activity can continue through April or even May, making vaccination valuable well beyond early winter.

We’re Here to Help

At ConvenientMD, we make flu vaccination easy and accessible. We offer flu shots to anyone, with or without insurance, at all of our locations in Maine, New Hampshire, and Massachusetts. Don’t let myths or misinformation leave you vulnerable this flu season. Take control of your health—and help protect those around you—by getting your flu shot today at ConvenientMD.