Take-up for the MMR vaccine in the area dropped significantly in the late 1990s when research – which has since been discredited – raised concerns over the jab.
Saturday has seen hundreds of people queueing at four local hospitals offering drop-in clinics for children and young adults.
The outbreak has affected nearly 600 people across south, west and mid Wales.
Measles is a terrible disease, but because it has been so well controlled by vaccination many people have forgotten how nasty it can be. Vanquishing measles epidemics completely also simultaneously eliminated the hard evidence that broad scale vaccination programs remained essential. Lacking direct experience with the disease and seeing little compelling counterbalancing evidence of need, public perceptions concerning risks vs. the benefits of immunization shifted toward a more skeptical view.
Skeptical assessments of medical procedures such as immunizations are valuable and have led to changed practices. For example, the US recommendations for poliomyelitis (polio) immunizations were changed over ten years ago when it recognized that control of polio virus infections was so effective that the relatively rare risk of side effects posed by continued use of the oral polio vaccine (OPV) were no longer justified. At that point, physicians began using inactivated polio vaccine (IPV) exclusively as it could provide full protection against disease without the risk of paralysis associated with the use of OPV.
Public health authorities will have to keep in mind that controlling diseases sometimes removes clear evidence of their threat. A measles resurgence in the UK now seems to have shifted the equilibrium in favor of immunization. Unfortunately, both diseases and public perceptions of risk are dynamic.
Commentary contributed by Tyler Kokjohn