Brian S. Koll, MD
Executive Medical Director for Infection Prevention and Control
The Mount Sinai Health System
The Best Time to Get a Flu Shot Is Now
As a specialist in infection prevention and control, I have often fielded the question, "When is the best time to get a flu shot?" Usually peaking in November, December, or January, flu season typically runs from September 1 through April 30. I got my flu shot in September, and urge anyone who hasn't been vaccinated this season to do it now.
Why Get a Flu Shot?
With rare exceptions, everyone who is six months of age or older should get a flu shot this year. Getting vaccinated can prevent you from coming down with this very serious, sometimes fatal, disease. It also keeps you from transmitting the virus to people who are vulnerable to life-threatening complications, including infection of the heart, lungs, or even the brain.
Vaccination is especially important for those at high risk for severe illness from flu, including pregnant women, young children, people with weakened immune systems or chronic medical conditions like heart disease and asthma, and those ages 65 and older (the immune system weakens with age).
When to Get a Flu Shot
Generally, the best time to be vaccinated for flu is September because it takes two to three weeks to develop immunity. You can get vaccinated anytime during flu season, but the Centers for Disease Control and Prevention (CDC) recommends doing so at least by the end of October. This will ensure protection as the weather gets colder and forces people to spend more time indoors and in close contact.
Advice for Older People
People 65 years of age or older should get a high-dose vaccine specially designed for their age group, as it induces a stronger immune response. Some older people are under the impression that they should wait until the end of October or even November to get vaccinated. But this is neither necessary nor recommended because it might result in missing chances to be vaccinated, or forgetting altogether.
The way flu shots work is another reason not to wait. The vaccine protects against the flu virus by establishing "memory" cells, which start to develop two to three weeks after you are vaccinated. When you are later exposed to flu, these memory cells make the antibodies that your body needs to protect itself. In theory, immunity wanes three to four months after vaccination, but that's only if you're not exposed to the flu virus during that time. In practice, if you are vaccinated in September, say, and the flu virus is circulating from November through February, your memory cells are constantly being reminded to maintain immunity, extending the vaccine's effectiveness.
However, memory cells don't remember forever, and flu viruses change from year to year. That is why the vaccine formulation is updated each year and why it's important to get vaccinated annually.
Get the Shot, Not the Spray
In recent years, a nasal spray flu vaccine called FluMist was offered as an option to people ages 2 to 49 as an alternative to the injectable vaccine. This year, however, getting the shot is essential because the nasal spray will not be effective and is not recommended by the CDC. During last year's flu season, those who got the spray did not have immunity, while those who got the shot did.
If you are allergic to eggs and concerned about receiving a flu vaccine produced with egg-based technology, you can request an egg-free vaccine. And if you are concerned about preservatives in vaccines--despite the lack of scientific evidence that they cause any harm--you can ask for preservative-free vaccine. A very small group of people, including those with severe, life-threatening allergies to flu vaccine, should not receive flu shots.
It is important to note that flu vaccine cannot cause the flu; the shots are made from dead influenza virus or no virus at all.
Staying Healthy During Flu Season
An annual flu shot is the number-one way to prevent flu, but getting lots of rest and eating a healthy diet are essential, too, as is washing your hands frequently with soap and water or hand sanitizer gels. If you are sick, don't go to work, where you might spread illness to others. And keep sick children home from school.
The three most important things to remember are: First, the flu vaccine is safe; second, getting vaccinated can save your life or someone else's; and finally, don't wait until November or December -- get vaccinated now.