Hepatitis B vaccine: Can I give blood?

I have recently been informed that my eleven year old has to have the hepatitis B immunization for school. My husband says that if she gets it that she will never be able to give blood in her life. Please let me know if this is true.

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Robert Steele

Robert W. Steele, MD, is a board certified pediatrician at St. John's Regional Health Center in Springfield, MO. He graduated from medical... Read more

The short answer to your question is no it is not true. Persons who receive the hepatitis B vaccine may give blood without any problem. However, the reasons why they are able to donate is somewhat complex involving concepts on how vaccines work and how donated blood is tested.

Vaccines work by tricking the body into thinking it has been invaded with the actual infection so that the body then continuously makes infection fighting molecules. This is usually done by injecting the body with parts of the actual virus or bacteria. Those parts are called antigens and the body's infection fighting molecules are called antibodies. Antibodies identify foreign viruses and bacteria and then attach to various sections of them. When these antibodies attach, it signals the rest of the body's immune system to come and destroy the virus or bacteria thus eliminating the infection.

The hepatitis B virus is made up of many proteins, the most important of which are the Core protein, the Envelope protein, and the Surface protein. They also go by the name of Core antigen, Envelope antigen, and Surface antigen. When a person gets infected with the Hepatitis B virus, his body begins to make antibodies against these three antigens. In other words, that person begins making Core antibodies, Envelope antibodies, and Surface antibodies. These antibodies usually persist for life.

Detecting someone who currently has the infection is done by testing for the presence of antigens or actual parts of the virus. Identifying someone who previously had the infection but has now successfully fought it off is done by testing for the antibodies. The hepatitis vaccine contains only the Surface antigen which lasts in the body several weeks. When this is injected, the body only makes Surface antibody. So, now let's go through what the blood bank does in the way of testing to understand why people who have had the hepatitis vaccine may still give blood:

The blood bank tests for the presence of two things, Surface antigen and Core antibody. If either of these two these are present, the blood donation is not used for transfusion, and the donor is notified.

Surface Antigen

Since the antigen is a part of the actual virus, the only way a person could have it in his body is if he is currently infected or received the vaccine within the last several weeks. Therefore, the blood bank always asks if you have had any immunizations within the last six months and will generally deny giving blood for several months after the vaccine. However, after this time period, all the antigen from the vaccine is gone having been replaced with antibody.

But if the blood bank only tested for surface antigen, they would miss all those who had truly been infected but successfully fought off the infection leaving no surface antigen to be detected. And even though they did fight off the virus, these people are denied giving blood just to be on the safe side. So, how are those people identified?

Core Antibody

As I said, those who have been infected will have antibodies to many of the hepatitis B proteins (antigens). Since there is no Core antigen in the vaccine, those who test positive for Core antibody can only have had the infection. Those who had the vaccine and have never been infected will not test positive for Core antibody.

Your husband is quite an insightful man for having the forethought to consider the possible consequences of your daughter getting the hepatitis B vaccine. With many blood banks having difficulty supplying the community with the blood it desperately needs, I find his concern quite touching. Hopefully, my roundabout explanation has not left you completely befuddled. Suffice it to say, your daughter will not have the noble opportunity to donate blood taken from her due to her hepatitis B vaccination.

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