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What are vaccines and preventable diseases?
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A vaccine is a biological preparation used as a preventive inoculation to confer immunity against a disease. The preparation usually employs an innocuous form of the disease-causing agent, which is in the form of killed or weakened bacteria or viruses. A vaccine may also be composed of the toxins or surface proteins of the infecting organism.
The mechanism of action of a vaccine is that the immune system of the body is stimulated to recognize the agent as foreign. Once this occurs, the immune system will destroy it and remember it so that if stronger forms of those infecting organisms enter the body, the immune system is prepared.
Killed vaccines are those that contain previously virulent organisms that have been destroyed. Attenuated vaccines are those that contain live organisms with the virulent properties removed. Other types of vaccines include conjugate, experimental, subunit, toxoid and valence.
Prophylactic vaccines are used to prevent future infections by natural pathogens. Therapeutic vaccines — particularly those to fight AIDS, cancer, hepatitis B, malaria and tuberculosis — are used to alleviate symptoms in those already infected with the disease. Therapeutic vaccines are currently under investigation.
It is recommended that children receive vaccinations as soon as their immune systems are developed enough to respond. As children mature, booster shots are administered to achieve full immunity. The Centers for Disease Control and Prevention (CDC), World Health Organization (WHO) and other professional health care organizations have accordingly developed vaccination schedules to fight various organisms and diseases. Sometimes two or more doses of a vaccine are required, and many must be administered months or years apart.
A selected list of vaccine-preventable diseases includes diphtheria, Haemophilus influenzae type b (Hib), hepatitis A and B, influenza, measles, meningococcal disease, mumps, pertussis (whooping cough), pneumococcal disease, polio, rotavirus (severe diarrhea), rubella (German measles), tetanus (lockjaw) and varicella (chickenpox).
Additional information about vaccines and preventable diseases may be found at these websites:
http://www.who.int/immunization_monitoring/diseases/en/
http://www.fda.gov/BiologicsBloodVaccines/Vaccines/default.htm
http://www.who.int/topics/vaccines/en/
http://www.gatesfoundation.org/vaccines/pages/default.aspx
http://www.cdc.gov/vaccines/vpd-vac/child-vpd.htm