If someone has suffered a major blood loss, should they be revaccinated after they recover?

      No, this is not necessary. Your immunologic memory resides primarily in your bone marrow. The only situation where a person should be re-immunized is if their bone marrow is ablated by drugs or radiation as with a bone marrow transplant.

If a patient is on antibiotics (e.g., tetracycline for acne) for chronic problem , would this have any effect on any live vaccine?

      No. Antibiotics do not have an effect on the immune response to a vaccine. No commonly used antibiotic or antiviral will inactivate a live virus vaccine.

Why can't inactivated vaccines be given to infants under 6 weeks old?

      The response to doses given before 6 weeks is poor, except for hepatitis B vaccine. .

What do you recommend if a person receives Hepatitis B or rabies vaccine in the gluteal area?

      The immunogenicity of hepatitis B vaccine and rabies vaccine is substantially lower when the gluteal rather than the deltoid site is used for administration. Doses of rabies vaccine administered in the gluteal site should not be counted as valid doses and should be repeated. Hepatitis B vaccine administered by any route or site other than intramuscularly in the anterolateral thigh or deltoid muscle should not be counted as valid and should be repeated, unless serologic testing indicates that an adequate response has been achieved.

How long can any inactivated vaccine remain refrigerated while in the syringe?

      If this is a manufacturer’s prefilled syringe, the vaccine is good until the expiration date as long as it is stored and handled properly and appears normal. We strongly recommend against prefilling your own syringes. However, if you have prefilled a syringe to administer and then for some reason the vaccine cannot be administered, we recommend you use the vaccine that same day if possible. If not, then it should be used within the next 24 hours.

How many people experience side effects following vaccination?

      In most cases, vaccines cause no side effects, or only mild reactions such as fever or soreness at the injection site.  Very rarely, people experience more serious side effects, like allergic reactions.  Severe reactions to vaccines occur so rarely that the risk is usually difficult to calculate.

Do multiple vaccinations increase the risk of side effects? 

      Many parents worry when their child needs to receive more than one vaccine at the same time.  Studies show that giving a child multiple vaccinations for different diseases at the same time is safe, effective and does not increase the risk of side effects. 

What signs of a moderate or severe reaction should I look for?

      After you or your child are vaccinated, look for any unusual conditions, such as a serious allergic reaction, high fever or behavior changes.  Signs of a serious allergic reaction include difficulty breathing, hoarseness or wheezing, hives, paleness, weakness, a fast heart beat or dizziness, and swelling of the throat.