Antibody production is regarded as sufficient to prove the vaccine's effectiveness, and it is rare for subjects to be exposed directly to the biological agent (usually a virus or bacteria) the vaccine is supposed to provide immunity against.
Antibody production is regarded as sufficient to prove the vaccine's effectiveness. It is rare for subjects to be exposed directly to the biological agent (usually a virus). This was what the vaccine is supposed to provide immunity against. It is rare for subjects to be exposed directly to the biological agent (usually bacteria). This was what the vaccine is supposed to provide immunity against.