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Flu shots: Frequently asked questions

Flu shots: Frequently asked questions

Your best shot for avoiding the seasonal flu - Flu shots now available

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Seasonal influenza, or flu, can cause significant illness. Between 2010 and 2020, the flu resulted in an estimated 9 to 45 million illnesses, 4 to 21 million medical visits, 140,000 to 810,000 hospitalizations and 12,000 to 61,000 deaths in the U.S. Influenza vaccines, commonly called flu shots, are your best defense against getting sick and the most effective way to control the spread of the virus.

Here are answers to some of the more common questions we’re hearing about seasonal flu and flu shots.

How does the virus spread?

The flu virus spreads easily. You can contract it when an infected person coughs, talks or sneezes and droplets get in your nose or mouth. Less commonly, you can also get the flu by touching something that has the virus germs on it, then touching your eyes, nose or mouth.

What types of flu shots are available?

The injectable influenza vaccine is made of inactivated or killed influenza. There’s the standard dose flu shot that’s given to people over the age of six months, as well as an enhanced version of the flu shot that is now recommended for people 65 and over. The enhanced vaccine (formerly known has high dose) gives older individuals a higher dose of the vaccine to try to improve the immune response and protection from the vaccine.

There also is a nasal spray flu vaccine that contains a live attenuated virus, which is available for certain groups of people. Learn more at

Which type of flu shots will be given at BCH clinics?

Patients coming into a BCH clinic will receive the standard dose shot, which is quadrivalent. A quadrivalent flu vaccine is designed to protect against four different flu viruses, including two influenza A viruses and two influenza B viruses.

For people 65 years and older, the enhanced quadrivalent influenza vaccine is now recommended and is available at BCH for the 2023-24 flu season for the first time.

Nasal spray flu shots will not be available at our clinics.

Who should get a flu shot?

A yearly flu shot is recommended for most everyone 6 months of age and older.

When's the best time to get the flu shot?

It is best to get the flu shot as soon as it becomes available in your area, which typically starts in September. The flu shot should not be delayed. If you receive the vaccine by the end of October, you will be fully protected for holiday travel in November and December.

If you’re pregnant, should you get a flu shot?

YES! All pregnant persons should get the flu shot. First, the inactivated or killed flu vaccination is safe during pregnancy. Second, illness from influenza can be more severe for the pregnant person. The added benefit of the flu shot is that antibodies formed from influenza vaccination are passed on to your newborn, as babies can't get the flu shot until they are 6 months old. Just be sure to get the shot, not the nasal spray.

How effective are flu shots at preventing the flu?

Effectiveness of the flu vaccine is closely monitored by the Center for Disease Control and Prevention (CDC) and changes annually depending on a variety of factors, including whether the vaccine matches circulating strains of the influenza virus with the average efficacy ranging from 40% to 60%. Importantly, studies also show that flu vaccination significantly reduces the chances of severe disease and death with breakthrough infection.

What are the side effects?

Many people experience no side effects. If you do, they only last for a day or so. The most common side effect is pain where the vaccine is injected, but a smaller number of people will experience generalized achiness, fever, tiredness and headache.

Do the vaccines at BCH contain thimerosal?

No, the vaccines at BCH do not contain thimerosal, because we use single-dose or single-use vials. Thimerosal is a preservative that is present in very small quantities in multi-dose vials of vaccines, and studies have shown that this preservative is safe.