link di alcuni autorevoli siti internet sui vaccini 
In italiano: www.epicentro.iss.it 

In inglese: 
http://www.who.int/immunization/en/
http://www.who.int/topics/vaccines/en/ 
http://www.cdc.gov/vaccines/ 
www.immunize.org 
http://www.chop.edu/service/vaccine-education-center/home.html 

In tedesco: http://www.rki.de/cln_179/DE/Content/Infekt/Impfen/impfen__node.html 

In francese: http://www.mesvaccins.net/home/index.php 
http://www.sante.gouv.fr/vaccinations-vaccins-politique-vaccinale.html