The vaccine will have side effects for some people. A vaccine
activates a person’s immune system. It causes the immune system to create antibodies
immune cells to fight off a specific virus or bacteria. When your immune system goes
into action, you may feel your immune system kick into gear as though it’s fighting
illness. This does not mean you are infected with an illness. It means that your immune
system is working.
People in the COVID-19 vaccine trials for this vaccine commonly had
soreness where the shot was given, tiredness, headaches, muscle aches, and nausea
day or two. Fewer people had redness and swelling at the injection site. These are
signs that your immune system is working on its defense. You can get these kinds of
effects after many kinds of vaccines. But these symptoms should last a short time.
comparison, COVID-19 symptoms can be severe and last much longer, and cause
complications, long-term illness, and death. The FDA approval process makes sure that
the discomfort and risks of a vaccine outweigh the risks and complications of the
illness it helps prevent.
Very rare cases of blood clots and low blood platelets have been
reported about 1 to 2 weeks after getting the J&J vaccine. For this reason, the FDA
advises the mRNA vaccine (Moderna or Pfizer) over the J&J vaccine. The FDA still
advises the J&J vaccine if the mRNA vaccine is not available or if a person would
not get vaccinated unless they get the 1-shot J&J vaccine. It's important to
remember that blood clots from the J&J vaccine are very rare--about 4 cases per 1
million people. The risk of complications from having COVID-19 are greater that the
risks from the vaccine. Talk with your healthcare provider.
In general, the COVID-19 vaccines are very safe. They have been
tested on thousands of people. Non-severe allergic reactions have happened in a few
people up to 4 hours after getting the vaccine. The vaccine clinic may ask you to
stay on-site for a period of time after you get the vaccine. This is to make sure
don't have an immediate reaction, and to treat you if you have one.
Talk with your healthcare provider before you get a COVID-19
vaccine. Tell them if you have ever had an immediate reaction to any vaccine, even
the reaction was not severe. Your provider will help you weigh the risks and benefits
of the COVID-19 vaccine for you.
The CDC has a smartphone app called V-Safe to help you report side
effects. To access this app, see "To learn more" below.