Some useful links :

1. World Health Organisation (WHO)
    www.who.int/topics

2. Indian Academy of Pediatrics
    www.iapindia.org

3. Centre for Disease control - USA
    www.cdc.gov/vaccines/acip/index.html

4. American Academy of Pediatrics
    www.aap.org

5. American Academy of Family Physicians
    www.aafp.org