Flu Vaccine Side Effects Facts - Children's Physicians Medical Group

Flu Vaccine Side Effects Facts

Every year, from October until May, the official “flu season” begins in the United States. Brought about by cold weather driving people indoors, the season results from close quarters and an increased probability for sharing germs. These germs spread in a variety of ways, from airborne transmission due to an ill-timed sneeze to touching the same surfaces as a sick person.

Another factor contributing to outbreaks of influenza are children returning to school.  Schools are prime locations for germs, where children share desks, pens, and, unfortunately, viruses and bacteria. In understanding the significance of influenza, consider the following statistics:

  • Children in the U.S. miss almost 38 million school days every year due to influenza.
  • Children between the ages of 5 and 17 miss on average 3 school days per year due to illness.
  • Only 56.6% of children between the ages of 2 and 17 received vaccination against the flu in the 2012-2013 season  – even lower for those who are exposed to “high-risk conditions”  (diabetes, asthma, HIV/AIDs, etc.).
  • On average, 20,000 children under the age of 5 are hospitalized each year because of complications related to influenza.

The 2012-13-flu season serves as a reminder of the unpredictability and severity of flu. Flu activity began early in the United States and was high for 15 weeks. The season also was more severe than recent seasons. Hospitalization rates, especially in older adults, were the highest recorded since U.S. Centers for Disease Control and Prevention (CDC) began tracking flu data, and deaths attributed to pneumonia and influenza were the highest recorded in nearly a decade. The number of pediatric deaths (164) also was the highest since pediatric death surveillance began, with the exception of the 2009 H1N1 pandemic when there were 348 pediatric deaths.

The CDC recommends that anyone over the age of 6 months should receive a vaccine to avoid spreading the flu in San Diego in 2014 and other major cities throughout the U.S. through travel.  Despite these statistics, there are many parents concerned with flu vaccine side effects in the 2014 season.

Flu vaccine side effects are typically mild, and can include soreness or itching at the injection site, headache, fatigue, fever, and muscle aches. Most of these symptoms clear up in a day or two following the vaccine. With the high prevalence of the flu in San Diego in 2013 and 2014, the benefits of the vaccine for this flu season far outweighs the mild side effects that might be experienced. 

Who is Most Likely to Experience Mild Side Effects?

As discussed, some people experience mild side effects from receiving the flu vaccine, but recover in less than two days;  some data to consider:

  • 64% of individuals receiving the flu vaccine have pain at the injection site, which usually resolves in 2 days without requiring any additional treatment.
  • Most people who experience any kind of fever or malaise are those who have never been exposed to influenza before, such as children, and the rates of experiencing these symptoms are the same between both those who received the injection and those who received a placebo during clinical trials.
  • A study involving 250,000 children aged 18 years revealed no clinically important adverse effects after receiving the flu vaccine.

 What about More Serious Side Effects?

Serious side effects from the flu vaccine are very rare, but some people should not get the vaccine.  You should not receive a flu vaccine if you have an active infection with a fever. Your physician will recommend waiting until a fever has passed to receive the vaccine. You should also not receive the flu vaccine if you are allergic to any of the components in the vaccine or have experienced a severe (life threatening) allergy to a prior dose of a seasonal influenza vaccine

Doctors try to balance the risks associated with the flu vaccine for some patients against the likelihood of developing complications from contracting influenza. There have been some indications that the flu vaccine, when administered at the same time as the pneumococcal vaccine, can increase the risk of seizures. This risk occurs due to the potential for fevers brought on by these vaccines. If you or your child have had any seizures, it is important to inform your healthcare professional so that he or she can determine whether your risk factor for a seizure outweighs the benefits of receiving these vaccines.


There are a number of misleading facts and figures out there about the flu vaccine and its potential side effects. Many of these statistics are overinflated or outdated. Due to the risks associated with catching influenza, parents and their young children, as well as the elderly and expectant parents, are strongly advised to receive the vaccine against the 2014 San Diego flu. The vaccine is the best way to avoid getting influenza and spreading it to other people. Children’s Physicians Medical Group in San Diego has comprehensive information for parents to help them make the best decision regarding vaccinating their children, and an informed decision is always the best decision.