Every fall we are faced with the same question: To get the flu shot or not to get the flu shot? There are so many myths surrounding the influenza vaccine that many people grapple with this decision yearly, even people who otherwise get all of their vaccines. Here is a list of common questions that I receive specifically about the flu shot, and their answers. Hopefully this will help you make the best decision for your family. For more information on vaccines in general, see my post here.
Isn’t the flu just a bad cold?
No. In fact influenza is a serious illness that causes sudden onset of high fever, sore throat, headache, fatigue and body aches. Many patients will also experience upper respiratory symptoms and/or gastrointestinal symptoms (vomiting or diarrhea). However, the stomach flu is NOT true influenza and a cold, while may cause similar symptoms, is not influenza. Patients with a common cold will have nasal congestion and runny nose, along with a cough. These patients may or may not have fever, may only be down a day or 2 and recover within 7-10 days.
Not only can influenza be incapacitating for up to a week with severe body aches and fatigue, but can also cause many complications. Patients are at risk for pneumonia, dehydration, worsening of chronic disease, hospitalization and death. Thousands of people die from the flu every year (over 36,000 in the 2014-15 season), and hundreds of thousands are hospitalized. While most deaths occur in the very young, very old or chronically ill, perfectly healthy people also die from the flu. In 2015, 90% of children who died from the flu did not have the flu vaccine.
Isn’t the flu shot a poor match for the actual virus circulating?
Influenza comes in many varieties. There are 2 main types, A and B. Furthermore, these types have a variety of different antigens on them. Antigens are proteins on germs that help the immune system recognize and kill them. One type is hemagglutinin (H) and the other type is neuraminidase (N). To make it more complicated, there are several sub-types of both H and N. For example, H1N1 caused a bad outbreak in 2009 after a shift in the antigens. The H1N1 Influenza A virus is now routinely part of the flu vaccine.
Each year the antigens on the virus “drift”, or change, so the vaccine is made by careful surveillance and estimation of what may cause the current season’s disease. Unfortunately it is very hard to get a perfect match. The good news is that in seasons with a close match, the vaccine has a high efficacy rate. Typically the shot has an effectiveness of 63%. In seasons with a poor match, there can still be partial immunity to the circulating virus from the vaccine. Furthermore, if enough people get their shot, then herd immunity will offer even more protection.
Why do I have to get the shot every year?
As stated above, the type of influenza circulating varies from year to year. On top of that, our immunity will wane over time, leaving us vulnerable to infection. Finally, some people may not make a good response to the vaccine in any given year. Therefore, the best way to prevent disease and reduce the spread of infection is to get the seasonal flu shot yearly.
Who should get the flu shot?
The vaccine is approved for people over 6 months of age. High risk patients like those with asthma, heart disease, immunocompromised conditions, children taking aspirin and pregnant women should be prioritized. Also, people who work in health care or who care for babies should receive their annual flu shots. Even if you don’t fall into one of these categories, the more people who are protected, the greater our herd immunity.
Which flu shot should I receive?
There are several different options for your seasonal flu vaccine. The trivalent injectable vaccine which, protects against 2 types of strain A and 1 type of strain B, and the quadrivalent version which covers the same types of strain A and B with an extra type of strain B. The American Academy of Pediatrics does not give preferential recommendation of one over the other.
There are also 2 ways to give the vaccine. The most common is the inactivated injection for which there are few contraindications. These include children under 6 months old and those with severe egg allergy (see below). The other option is the live attenuated influenza vaccine (LAIV) which is given nasally and not by injection. This option is available for people 2 years to 50 years of age and while less painful, has more contraindications. There is also now a strong recommendation against using LAIV in kids (see below). People who should not receive the LAIV can be found on the CDC website and include:
- Anyone with an allergy to one of the components or to eggs
- Pregnant women
- Children on aspirin therapy
- People with weakened immune systems
- Children 2-4 years of age who have had wheezing in the previous 12 months
As of June 22, 2016, the American Academy of Pediatrics no longer recommends the LAIV for children. The reason for this change is 3 years of data showing poor effectiveness against the H1N1 strain of the flu, as well as decreased effectiveness against H3N2 due to drift. H1N1 was the most common strain of flu A seen in the 2015-16 season with H3N2 a close second.
What if my child has an egg allergy?
Previously, it was not recommended for children with egg allergies to get a flu shot because the vaccine contains a very small amount of egg protein. However, it is now known that many people with mild egg allergy can safely get the flu shot. If your child has a confirmed allergy by an allergist but is able to tolerate foods baked with egg or only has mild hives when they eat egg, they can get the shot in the pediatrician’s office. Be prepared to wait for 30 minutes to watch for reaction afterwards. If your child has anaphylaxis to egg then it is best to discuss your options with the allergist or pediatrician. We now believe that it is safe to give flu shots to those kids who do have anaphylaxis but the vaccine should be administered under careful observation.
When is the best time to get my flu shot?
The best time to get the flu shot is before any potential exposure to the flu. It takes about 2 weeks for the flu shot to be fully active and for your body to have immune cells that are ready to go. Talk to your doctor about when flu season begins in your area so you can schedule your shot accordingly. This brings me to my final question:
Can you get the flu from the flu shot?
The answer is no. Again, the shot is not a live virus so you can not get virus from it. Getting your shot too late in the season (see above), increases your risk of exposure to influenza prior to vaccination or within the 2 weeks following vaccination, resulting in infection. Therefore, it may seem like you got the flu from the shot when in reality you did not. Furthermore, children get frequent colds and gastroenteritis in the winter so it is possible for them to be infected with other viruses in the time surrounding vaccination. Again, this may seem like they got sick from the vaccine itself.
The nasal mist is live attenuated so it is possible to get mild flu-like symptoms following vaccination. These symptoms usually last a day or 2 and are not nearly as severe as an actual influenza infection. It is possible to feel achy or under the weather for a day or 2 following any vaccination. This is a sign that your immune system has been triggered, which is exactly what you want! Again, this does not mean that the immunization itself has made you sick.