COULD PARENTS BE HELD LIABLE FOR NOT IMMUNIZING THEIR CHILDREN

Although most vaccines are highly effective, vaccination does not confer 100% immunity to all those immunized, and some individuals are unable to receive vaccinations. But the phenomenon of herd immunity, which arises when a large enough percentage of the population is vaccinated, more completely prevents the development of disease outbreaks by disrupting the possibility of person-to-person transmission of a pathogen. In the presence of an outbreak of a vaccine preventable disease, such as measles, a percentage of those who develop the illness may well have received the vaccine, since effectiveness of the vaccines in individuals varies. The implication of these basic scientific facts is that the decision by some parents to not vaccinate their children amplifies the possibility for an otherwise preventable outbreak to occur, and places even children who are vaccinated at risk. This issue has gained some currency at a time when vaccination concerns are rising. In our analysis, using measles as an example, we examine the question of whether parents whose immunized children have contracted a disease due to breakdown in herd immunity may have recourse in tort against those parents who have refused to immunize their children. There are a few barriers to success which such parents may face. At the outset, identifying a specific individual as responsible would be virtually impossible. However, the potential to hold liable a group of parents who chose not to vaccinate their children does exist. In a disease like measles, with a low threshold for loss of herd immunity, it is possible to identify a small number of individuals, often in a geographical or social cluster, whose collective decision not to immunize has led to an outbreak. As a result, it can be said that each member of this group materially contributed to the emergence of an outbreak, which would not likely have occurred otherwise. However, while this may potentially be an answer to the causation problem, a main limitation to such an approach is the question of foreseeability, that parents may not know when making decisions on vaccination that they could be putting other children, including vaccinated children, at risk. The other major limitation is that under the status quo, exemptions to school-based immunization programs are authorized by statute and are presented as choices which relate only to individual, rather than to community health. Under such a regime it is unlikely that a parent of an injured child could succeed in tort, when the supposedly negligent actions have been either explicitly or implicitly approved by the public health authorities. We hypothesize that an altered regime of disclosure and risk assumption in childhood immunization exemptions could have the effect of removing the statutory authority defence and of making parents aware of the possible negative consequences to other children. This would require clear transmission of information to parents that the decision to vaccinate a child is not only for the benefit of the individual child, but also the benefit of other children with whom the child may come into contact.