[Travellers chick]

I was just curious if the shots in the series are different from one to the other. For instance, is shot one different from shot two? Or all they all the same and it's just that you need to be exposed 3 times to develop an immune response?

[neverwintergirl80]

The most commonly used vaccine for hepatitis B in the US is Engerix B, manufactured by GSK.

These vaccines are administered with the same level of hepatitis B surface antigen, so your first, second and third vaccination for hepatitis B are all the same.

[caufrican]

Doses 1, 2, and 3 are the same.

There are two different brands.
Energix-B http://www.fda.gov/downloads/BiologicsBloodVaccines/Vaccines/ApprovedProducts/UCM224503.pdf
and
Recombivax HB http://www.fda.gov/downloads/BiologicsBloodVaccines/Vaccines/ApprovedProducts/UCM110114.pdf

Some people will develop the desired immune response after just one shot. For some, it will take two, and for others, three shots. And for some, even three doesn't do it. But they have to stop somewhere. Three shots are recommended because they don't want to bother checking the blood for antibodies after the first or second shot.

[AlphaOne_]

The three doses are the same. Like other inactivated (not live) vaccines, multiple doses are needed to achieve long-lasting immunity. The additional doses boost the immune system, producing much higher and long-lasting levels of antibody with each additional dose. Live vaccines work completely differently. With live vaccines, like MMR, the live weakened vaccine virus replicates in the body as in an actual infection. This process produces lifelong immunity in most people with a second dose. Additional doses are recommended to catch the few people who do not respond to the first dose, but it is perfectly acceptable to skip the second dose of live vaccines if adequate immune response is shown with a blood test. This is not the case with hepatitis B and other inactivated vaccines. Doctors do not test after each dose of these vaccines because they know how vaccines work and they know that long-lasting immunity requires multiple doses.