Vaccines are dead or deactivated disease-causing organisms, or mild derivatives of such organisms. They stimulate the body's immune system to recognize, destroy and "remember" these organisms so that when the more deadly or stronger organisms attack, the immune system has already built up its defenses.

Maintaining high immunization rates is important to ward off outbreaks or epidemics of an infectious disease.

Some countries adopt compulsory vaccination against certain diseases, while some other countries leave it to parents to make the decisions on whether or not to inoculate their children.

Not all individuals respond to vaccines.

Once vaccinated, most individuals will develop a milder form of the disease even if they do succumb to the infection.

Vaccination does not necessarily provide life-long protection. The more purified the vaccine is, the longer its effect will last.

People with immune deficiency or associated diseases should be careful about getting vaccinated.

Consult a doctor about your health condition before getting vaccinated. It is also wise to stay at the clinic for at least 30 minutes in case the patient develops severe side effects.