Understand immunology? Like what antibodies do not determine immunity?
"Effective" means that a vaccine is injected (vaccination) into the patient, and the patient develops an antibody. Vaccination does not mean that the patients develops an immunity.
Scientists prove that the antibodies from vaccinations
ARE NOT NEEDED.

To prove this, scientists from HARVARD MEDICAL SCHOOL, M.I.T., massachusetts general, san raffaele institute (Italy), and other institutes, co-authored and published on how they removed all antibodies from mice, leaving only B-Cells, which successfully fought off lethal viruses. This debunks vaccine manufacturers who say that vaccines are necessary to convey immunity. This
suggests that repeated vaccinations could be the reason why some vaccinated people lose their natural immunities, as their body tends to unnaturally rely on temporary, antibody-based immunities.
Immunity 2012 Mar 23; 36(3): 415-426:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3359130/pdf/nihms-377739.pdf

there is more to the immune system than just antibodies

I will repeat myself as many times as drug commercial repeat themselves about all the damn side effects just to get a hard on