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Immunization Science

Misinformation Can Cause Disease Outbreaks

The article

Impact of anti-vaccine movements on pertussis control: the untold story. Gangarosa EJ, Galazka AM, Wolfe CR, Phillips LM, Gangarosa RE, Miller E, and Chen RT.  Lancet 1998;351(9099): 356-361

Explanatory Note: Whole cell pertussis (whooping cough) vaccines were important in the control of whooping cough in all the developed countries and continue to be widely used worldwide. As the number of cases of pertussis declined with vaccine usage the attention of some parents switched from concerns about the disease to concerns about possible serious adverse events—often coincidental—of immunization. In a number of countries, publicity about these concerns led to the rise of anti-vaccine movements, some of which had serious impact on vaccine utilization. This paper examines the impact of these anti-vaccine movements on the amount of whooping cough in the different countries.

The question

Did anti-vaccine movements affect the rates of whooping cough cases?

The study

This study analyzed the incidence (number of new cases/100,000 population) of whooping cough in different countries over time.

The researchers divided the countries into those where the anti-vaccine movements had limited impact on the amount of vaccine administered and countries whose immunization programs were disrupted by movements against the use of the whooping cough whole cell vaccine.

The findings

This study found that whooping cough incidence was 10 to 100 times higher in countries where immunization programs were compromised by anti-vaccine movements than in countries where high vaccine coverage was maintained.

The relevance/bottom line

The findings of this study showed a causal relationship between movements against whole-cell pertussis vaccine and pertussis epidemics.

NNii’s comments

The methods employed in this study only demonstrate trends, not precise comparisons. Nevertheless, it emphasizes that public perception of vaccine risks—even if not supported by scientific evidence—can deter immunization acceptance with tragic consequences.