Flu Shot Facts - The Best Way to Fight the Flu

The seasonal flu shot is a yearly vaccine that is administered to protect against the flu, or the influenza virus. In the United States, flu shots are recommended for everyone above 6 months old. According to the CDC - the Centers for Disease Control and Prevention - individuals and families should strongly consider receiving the flu vaccination. 

The flu can be a very serious illness, especially in young children, adults ages 65 and older, those with underlying health conditions, and pregnant women. The CDC says that the flu shot is the best way to protect yourself and your family from the flu. 

Strains of the flu virus are constantly changing, so new flu vaccines are made each year. Scientists make the vaccine before the flu season actually starts, as they predict which flu strains are likely to be the most common during the upcoming season. 

Doctors say that since the flu virus frequently changes its genetic composition, the vaccine needs to constantly be updated and reformulated, which is one of the reasons why people have to get the flu shot on a yearly basis. 

The Types of Flu Shots

Flu shots protect against three or four strains of the flu virus. Trivalent flu vaccines protect against two influenza A strains - H1N1 and H3N2 - as well as one influenza B strain. Quadrivalent flu vaccines protect against the same strains as the trivalent vaccine, as well as an extra influenza B strain. 

In addition to the standard dose of the flu vaccine given through a needle, flu shots are available in several different forms, including a high dose version for those 65 and older, a small needle version for people ages 18 to 64, an egg-free version that is grown in animal cells rather than hen's eggs, and is approved for people ages 4 and older, and finally, a nasal spray, which is approved for healthy people ages 2 to 49.

The CDC also says that there is a needle free flu shot, delivered by a jet injector, which uses a high pressure stream of fluid to inject the vaccine. The CDC says it is approved adults ages 18 to 64.

Flu Vaccines for 2018 - 2019 Season

According to the CDC, the composition of the 2018 - 2019 flu shot will be slightly different from the 2017 - 2018 season. Specifically, there will be a different strain of the H3N2 virus, and a different strain of the influenza B virus in this season's flu shot.

The CDC says that it made a change to the influenza B component of the vaccine because of an increase in circulation of influenza B strains that have changed genetically, compared with earlier strains. The agency says that the change to the H3N2 component, addresses concerns that this strain of the virus somewhat changes when it's grown in eggs during the manufacturing process. When the new H3N2 component is grown in eggs, it appears more similar to circulating flu viruses, compared with the strain that was used in the 2017 - 2018 season.

What About the Nasal Spray?

For the past 2 years, the CDC hasn't recommended the flu nasal spray. Now, however, they are recommending the spray for the 2018 - 2019 flu season.

During the 2016 - 2017 season and the 2017 - 2018 season, the CDC omitted the nasal spray, called FluMist - because data showed that the nasal spray was not effective at preventing the flu from the years 2013 to 2016. This year, Astra Zeneca, the maker of FluMist, says that it has changed the formulation of the spray slightly, and produces a better immune response on U.S. children than the old one. 

Note: The nasal spray is licensed for healthy people ages 2 through 49, but it is not recommended for pregnant women.

Still, the American Academy of Pediatrics - or the AAP, says that they advise families to choose the flu shot, rather than the nasal spray during this years season. The AAP says that the injectable has been proven more effective against most strains of the flu virus over the past several flu seasons, but the nasal spray could be used this year as a last resort for children who cannot receive a flu shot. 

Members of the AAP say that if parents choose the nasal spray vaccine, they need to be aware that, depending on the performance of the new vaccine formula, there might be a chance that your child, or yourself will not be fully protected. The effectiveness of the new nasal spray formula has not been determined as of yet. 

When to Get The Flu Shot

The flu season's starting and ending date is often unpredictable, but health officials recommend that people should receive their flu shot in early fall - preferably by the end of October, according to the CDC. Flu activity typically peaks in January or February. 

The CDC says that most flu vaccines are given before Thanksgiving, but that people can still get their shot throughout the winter months, although it may be considered "too late" to get a flu vaccine after March. Each season's flu shot expires in June of that year.

It is important to note that after vaccination, it takes a person approximately 2 weeks to build up immunity against the flu.

Effectiveness of the Flu Vaccine

The effectiveness of the seasonal flu vaccine depends on how well the flu strains in the vaccine match the strains in circulation. Some studies show that when strains in the vaccine are a good match with the ones that are circulating, vaccinated people are 60% less likely to catch the flu, than people who aren't vaccinated, according to the CDC.

Flu vaccine effectiveness can vary depending on the person who is being vaccinated. For instance, the vaccine tends to work best in healthy adults and older children, and less well in older adults.

Some studies suggest that people who do get sick develop less severe symptoms if they are vaccinated. A 2013 study that was published in the Journal Clinical Infectious Diseases found that people who got the flu shot were less likely to be hospitalized with the flu.

There are also some studies that suggest that the high dose flu vaccine provides better protection for older adults. The high dose flu vaccine contains four times the dose of the standard vaccine.

Are Flu Vaccines Safe for Pregnant Women?

According to the CDC, studies show that the flu vaccines are safe for women in any stage of pregnancy. In fact, there are several reasons why it's important for pregnant women to get the vaccination.

When pregnant women get influenza, they have a tendency to develop a more severe disease, and are at an increased risk for complications and hospitalization from the disease. In addition, the flu vaccination in pregnancy helps to protect the baby against the flu during the first 6 months of life, when the baby is far too young to receive a flu shot. The mother passes that protection on to her newborn baby. 

Side Effects

According to the CDC, mild side effects from the flu shot include: soreness, redness or swelling at the injection site, low-grade fever, and aches. Approximately 1 to 2 percent of people who get a flu shot will have a fever as a side effect, says the CDC.

Rare, but serious side effects can occur, including allergic reactions. Symptoms of serious side effects include: difficulty breathing, swelling around the eyes or lips, hives, racing heart, dizziness, and high fever. If you experience any serious side effects, you should immediately seek medical attention.

For children: the side effects from the flu nasal spray can include: runny nose, wheezing, headache, vomiting, muscle aches, and fever. For adults: the side effects from the flu nasal spray can include: runny nose, headache, sore throat, and cough. These side effects can last a short time compared to the actual flu illness, the CDC says.

The Myth: Do You Get the Flu From the Flu Shot?

The answer is no. Contrary to popular belief, you cannot catch the flu from the flu vaccine. The viruses in the flu shot are dead, so people specifically can't contract the flu from the vaccination itself.

Now, as stated above, it does take two weeks for the vaccine to kick in, and because of that, they may catch the flu shortly after they're vaccinated if they are exposed during that two week time period. The CDC says that some people may also mistakenly attribute symptoms of a cold to the vaccine.

The nasal spray vaccine contains a "live attenuated" flu virus, but the virus is weakened so that it cannot cause the flu. The viruses in the nasal spray can't replicate in the warm temperatures of the lungs and other parts of the body. However; because temperatures in the nose are colder, the virus causes a small infection in the nose. This infection does not cause symptoms in most people, but in some, it can cause symptoms such as a runny nose or sore throat.

The local infection will prompt the body to immediately make antibodies against the flu virus, which in turn will provide better protection against the real flu.

Who Shouldn't Get A Flu Vaccine?

Children younger than 6 months old cannot receive a flu vaccine. Those who have had a severe allergic reaction to the flu vaccine in the past should generally not be vaccinated, as well.

If you have a high fever, you shouldn't receive the flu shot until the fever is gone. However, if you have a minor illness, such as a mild cold or headache, you can still receive the flu vaccination.

If you have any questions or concerns, it is always best to consult a medical professional before vaccination. They will be more than willing to answer any questions that you may have!