Vaccine Refusal Suggested Cause for Recent Outbreaks

The US has seen a surge in outbreaks of preventable diseases. A recent study carried out by Emory University researchers and published in JAMA on March 15, 2016, attributes this rise in infections to the growing number of individuals who are refusing vaccines.

Those who refuse vaccines not only compromise their own health, but also the health of those around them. Upon suspecting a correlation between vaccine refusal and outbreaks, Emory researchers (supported by an award from the Emory Vaccinology Training Program of the National Institute of Allergy and Infectious Diseases) analyzed medical literature in search of reports of measles outbreaks in the US since January 1, 2000 (when the disease was officially declared eradicated from the continental US), as well as endemic and epidemic cases of pertussis (whooping cough) since January 1, 1977 (the lowest point in pertussis outbreaks in the US). The study also examined 4 studies which investigated the risk of infection due to the delay of or exemption from vaccines.

Measles Vaccine History

Eighteen published studies reported 1,416 measles-infected cases in individuals ranging from 2 to 84 years of age, 178 of which were identified to be younger than one year of age. Exactly 57% of the individuals in these cases had not received any measles vaccines. Of the 970 cases with a previous history of vaccination, 574 did not receive measles vaccination, despite being eligible. (A total of 71% of the 574 cases did not have religious reasons for exemption, while 42% had medical contraindications.)

Pertussis Vaccine History

The research team also identified 32 reports of pertussis outbreaks, which yielded a total of 10,609 pertussis cases, with individuals ranging from 10 days to 87 years of age. Within the 4 states reporting the 5 largest numbers of statewide epidemics (Arizona: 781 cases in 1988; California: 4,415 in 2010; Washington: 1,829 cases in 2012; Oregon: >900 in 2012; and California: 222 in 2014), 24-45% of the cases were in unvaccinated or undervaccinated individuals. Outbreaks occurred among highly vaccinated populations as well, which signifies an increase in immunity to the pertussis vaccine. Of the 32 outbreak reports, 9 reports included detailed vaccination history for cases that did not receive pertussis vaccines. These 9 reports detailed 12 outbreaks, 8 of which described the infected population as mostly unvaccinated individuals (58% to 93% unvaccinated).

Research Outcome

Noting the rise of measles and pertussis infections in the unvaccinated population as well as within the surrounding community, the researchers recommend making vaccination mandatory throughout the country, even if it goes against parent wishes. According to the authors, “This review has broad implications for vaccine practice and policy. For instance, fundamental to the strength and legitimacy of justifications to override parental decisions to refuse a vaccine for their child is a clear demonstration that the risks and harms to the child of remaining unimmunized are substantial. Similarly, central to any justification to restrict individual freedom by mandating vaccines to prevent harm to others is an understanding of the nature and magnitude of these risks and harms. However, the risks of vaccine refusal remain imperfectly defined, and the association between vaccine refusal and vaccine-preventable diseases may be both population- and disease-specific.”

In an editorial response to the findings, Matthew M. Davis, MD, MAPP, of the University of Michigan, Ann Arbor, wrote that once the development of vaccines for life-threatening diseases becomes a reality, “the public will likely expect the currently complex and heterogeneous vaccination system in the United States to function as a seamless organization.” He went on to explain that Americans are concerned with the safety, availability, and effectiveness of such vaccines, as well as the durability of the immunity they bring. He notes that these measles and pertussis outbreaks provide an opportunity to improve the current vaccination approach in order to broaden vaccination coverage and limit waning immunity, thus limiting preventable disease infection in both children and adults.