Scientists were looking to use antibody levels as a reliable standard for comparing different vaccines.

Several types of blood tests may be used to examine antibody levels in the blood.

At this phase the immune response is still developing and antibody levels against the virus are often too low to be detected.

People originally got interested in bovine colostrum because of the high antibody levels.

While antibody levels always fall over time, this would be a more rapid loss of immunity than expected for that vaccine.

It takes four to six weeks for the antibody level to reach its maximum protective level, and by now everyone should be there.

Among the people providing care but receiving no stress training, only 7 percent achieved that antibody level.

They will also measure antibody levels in the volunteers' blood at several intervals after the vaccinations.

When maternal Rh antibody levels are too high, an amniocentesis may be done.

A person with a cold or flu may have high antibody levels, he said, and these antibodies will stick to silicone.