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preventive health services

Flu Vaccination

Why is this important?

The flu is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. The virus is contagious, that is it can spread from one individual to the next easily. It can cause mild to severe illness, and at times can lead to death.

The best way to prevent the flu is by getting a flu vaccine each year. There are three types of influenza viruses: A, B and C. Human influenza A and B viruses cause seasonal epidemics of disease almost every winter in the United States. The emergence of a new and very different influenza virus to infect people can cause an influenza pandemic. Influenza type C infections cause a mild respira- tory illness and are not thought to cause epidemics.

A flu vaccine is needed every season for two reasons. First, the body’s immune response from vaccination declines over time, so an annual vaccine is needed for optimal protection. Second, because flu viruses are constantly changing, the formulation of the flu vaccine is reviewed each year and sometimes updated to keep up with changing flu viruses. For the best protection, everyone 6 months and older should get vaccinated annually.

The flu is different from a cold. The flu usually comes on suddenly. Most healthy adults may be able to infect other people beginning one day before symptoms develop and up to five to seven days after becoming sick. Children may pass the virus for longer than seven days. Symptoms start one to four days after the virus enters the body.

That means that you may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick. Some people can be infected with the flu virus but have no symptoms. During this time, those persons may still spread the virus to others. People who have the flu often feel some or all of these symptoms:

  • Fever or feeling feverish/chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle or body aches
  • HeadachesFatigue (tiredness)
  • Some people may have vomiting and diarrhea, though this is more common in children than adults.

Pneumonia, bronchitis, sinus and ear infections are examples of complications from flu. The flu can make chronic health problems worse. For example, people with asthma may experience asthma attacks while they have the flu, and people with chronic congestive heart failure may experience worsening of this condition that is triggered by the flu.

Anyone can get the flu (even healthy people), and serious problems related to the flu can happen at any age, but some people are at high risk of developing serious flu-related complications if they get sick. This includes people 65 years and older, people of any age with certain chronic medical conditions (such as asthma, diabetes, or heart disease), pregnant women, and young children.

Flu (Influenza) is a serious disease that can lead to hospitalization and sometimes even death. Every flu season is different, and influenza infection can affect people differently. Even healthy people can get very sick from the flu and spread it to others.

During recent flu seasons, between 80% and 90% of flu related deaths have occurred in people 65 years and older. “Flu season” in the United States can begin as early as October and last as late as May. During this time, flu viruses are circulating at higher levels in the U.S. population.

Most people who get influenza will recover in a few days to less than two weeks, but some people will develop complications (such as pneumonia) as a result of the flu, some of which can be life-threatening and result in death.

What are the risks?

The flu shot: The viruses in the flu shot are killed  (inactivated), so  you cannot get the flu from a flu shot. Some minor side effects that may occur are:

  • Soreness, redness, or swelling where the shot was given
  • Fever (low grade)
  • Aches

The nasal spray: The viruses in the nasal spray vaccine are weakened and do not cause severe symptoms often associated with the flu. In children, side effects from the nasal spray may include:

  • Runny nose
  • Vomiting
  • Wheezing
  • Muscle aches
  • Headache
  • Fever

In adults, side effects from the nasal spray vaccine may include:

  • Runny nose
  • Sore throat
  • Headache
  • Cough

How do flu vaccines work?

Flu vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with the  viruses that are in the vaccine. Traditional flu vaccines made to protect against three dif- ferent flu viruses are available. In addition, flu vaccines made to protect against four different flu viruses also are available.

The flu vaccine for three flu viruses protects against two influenza A viruses (an H1N1 and an H3N2) and an influenza B virus. The following flu vaccines are available:

  • Standard-dose flu shots for three viruses are manufactured using virus grown in eggs. There are several different flu shots of this type available, and they are approved for people of different ages. Some are approved for use in people as young as 6 months of age. Most flu shots are given with a needle. One standard dose flu shot also can be given with a jet injector, for persons aged 18 through 64 years
  • The four-virus flu vaccine protects against two influenza A viruses and two influenza B viruses.
  • A four-virus flu shot that is manufactured using virus grown in eggs. There are several different flu shots of this type available, and they are approved for people of different ages. Some are approved for use in people as young as six months of age. The number of individuals needed to receive a flu shot and prevent one case of the flu, is 12 to 40.

Frequently asked Questions about flu shots

What are the benefits of getting a flu shot?
While how well the flu vaccine works can vary, there are a lot of reasons to get a flu vaccine each year.

  • Flu vaccination can keep you from getting sick from flu. Protecting yourself from flu also protects the people around you who are more vulnerable to seri- ous flu illness.
  • Flu vaccination can help protect people who are at greater risk of getting seri- ously ill from flu, like older adults, people with chronic health conditions and young children (especially infants younger than 6 months old who are too young to get vaccinated).
  • Flu vaccination also may make your illness milder if you do get sick or reduce the risk of more serious flu outcomes, like hospitalizations.

When and where can I get a flu vaccine?
Flu vaccine is produced by private manufacturers, and the timing of availability depends on when production is completed. Flu vaccination should begin soon after vaccine becomes available, if possible by October. However, as long as flu viruses are circulating, vaccination should continue to be offered throughout the flu season, even in January or later. While seasonal influenza outbreaks can happen as early as October, during most seasons influenza activity peaks in January or later. Since it takes about two weeks after vaccination for antibodies to develop in the body that protect against influenza virus infection, it is best that people get vaccinated so they are protected before influenza begins spreading in their community.

What about the argument made by some people that vaccines don’t work well...that diseases would be going away on their own because of better hygeine and sanitation, even if there were no vaccines?
That simply isn’t true. Certainly, better hygiene and sanitation can help prevent the spread of disease, but the germs that cause disease will still be around. As long as germs still exist, they are they will continue to make people sick. A vaccine is approved only if FDA determines that it is safe and effective for its intended use.