Most vaccines don't produce immunity until at least two weeks after they're given, so visit a doctor four to eight weeks before departure.

Infection with one serotype is thought to produce lifelong immunity to that type, but only short term protection against the other three.

They also found that these same suppressor T-cells are what produce at least temporary immunity to the plant oil.

Vaccines that produce lifelong immunity can prevent some viral infections.

Then physicians began to realize that for some children, the vaccine given at so young an age did not produce immunity.

Vaccine: A product that produces immunity therefore protecting the body from the disease.

That means the virus is able to produce immunity in the body without causing illness.

He and his colleagues wondered whether another antigen, common to all the serotypes, might play a part in producing immunity.

Most vaccines don't produce immunity until around two weeks after they're given.