Vaccination associations and public concern

Beyond the true vaccine reactions that are well documented and have been illustrated throughout this module, the notion that vaccines could be responsible for serious health problems has led to many allegations and many scientific reviews. Some allegations often based on unfounded rumours or poor science have, at times, profoundly affected the performance of immunization programmes and limited the ability to prevent serious diseases. More on rumours and how to manage can be found in Module 6.

For other health conditions, the scientific evidence available is insufficient to conclude that the association is real, but also insufficient to exclude a link. Systematic study of such conditions can be made difficult as the frequency of a true reaction can be extremely low, or effects would be very mild or they occur many years after vaccination. In recent years, the availability of large computerized databases has allowed testing of many of those potential delayed associations, demonstrating nearly ubiquitously that there is no evidence for a link.

You can learn more about balancing vaccine efficacy and safety of vaccines, and the risks of measles infection versus the risks of the measles vaccine, in Module 1.