By Madeleine Winter
Within the past decade, there has been a significant resurgence of measles outbreaks in the United States. Between January 1 and March 14 of 2019, the CDC reported 268 individual cases of measles in 15 states. In 2018, the CDC reported a total of 372 cases of measles and in 2014, a record number of 667 cases in 27 states. Measles was declared as eliminated from the United States in 2000, which makes these recent statistics particularly concerning.
Measles is a highly contagious viral illness which may cause fever, cough, conjunctivitis, an extensive bodily rash, nasal congestion, but can result in more serious complications such as pneumonia, encephalitis and death. According to the CDC, on average 1 or 2 children out of 1,000 children with measles die from complications. The measles vaccine, commonly administered as the MMR vaccine (a combination of vaccines for Mumps, Measles and Rubella), is about 93% effective with only one dose and 97% effective with two doses. It is recommended that individuals receive these immunizations first between the ages of 12 and 15 months and then between the ages of 4 and 6.
Infants too young to receive the measles vaccine are particularly vulnerable to measles and its fatal complications, which makes them reliant on herd immunity — when at least 95% of the community receives both doses of the vaccine — to limit the spread of disease. However, herd immunity has been increasingly challenged by unvaccinated communities and vaccine hesitancy. In 2017, only 91.1 percent of children in the United States between the ages of 19 and 35 months received the MMR vaccine, while at least 95% of the community needs to be vaccinated to preserve herd immunity. The concept of herd immunity indicates how vaccine hesitancy and undervaccination poses a threat not only to the individual, but also to the greater community and its immunocompromised populations.
Vaccine hesitancy and the anti-vaccination movement poses a global public health threat. While some of the concerns surrounding vaccines arise out of cultural practices and misunderstanding of science, skepticism of vaccines was heightened by the British doctor Andrew Wakefield’s study published in The Lancetin 1998 that claimed there was a correlation between the MMR vaccine and autism. While the study was proven to be highly inaccurate and based on insufficient data and was later redacted by The Lancet, it helped fuel the rise in vaccine hesitancy.
The increase in measles outbreaks is also heavily associated with the persistence of unvaccinated communities. According to a 2017 study in JAMA Pediatrics, parents’ decisions to resist vaccination for their children “are often influenced by misinformation, false claims regarding vaccine safety, and a low perceived risk of infectious diseases among other factors.” While many public school systems have instituted certain vaccination requirements for children to attend, exemptions for personal belief and other nonmedical purposes have been increasingly used by parents to circumvent these requirements and enables populations of children to remain unvaccinated. The JAMA Pediatrics study further demonstrated the severe consequences of vaccine hesitancy surrounding the MMR vaccine, as it claimed a 5% decrease in MMR vaccine coverage in the United States would lead to a threefold increase in measles among children between the ages of 2 and 11 each year and would consequently result in $2.1 million dollars in public sector costs.
The consequences of under-vaccination were especially evident in a 2017 outbreak of measles among Somali immigrants in Minneapolis, Minnesota. Due to fears that the MMR vaccine caused autism, many Somali parents refused vaccination of their children and between 2004 and 2010, MMR vaccine administration among Somali children dropped from 91% to 54%. This thus contributed to an outbreak of measles in the Minneapolis-St. Paul Metropolitan area, where 64 out of the 79 reported cases of measles were under-vaccinated Somali Americans.
Similar to the outbreaks in Somali refugee communities, many of the 17 measles outbreaks documented in the United States in 2018 were linked to Orthodox Jewish communities, where significant amounts of the population are under-vaccinated.Foreign travel has particularly facilitated these outbreaks. The outbreaks in the Orthodox Jewish communities were associated with travelers who had contracted measles in Israel and brought it back to the United States. Similarly, the massive measles outbreak at Disneyland in California, which evolved into a 147 case, multi state outbreak, was most likely initiated by an infected individual from overseas who visited the amusement park and subsequently exposed hundreds of other customers.
The rise in measles outbreaks and the continuation of vaccine refusal and hesitancy among some sectors of the populations constitutes a major public health threat. Extensive educational reform, vaccination programs and engagement of policy makers are necessary to combat anti-vaccination sentiments, preserve herd immunity and ultimately, protect public health nationwide.
SOURCES
https://www.cdc.gov/measles/cases-outbreaks.html
https://www.cdc.gov/vaccines/pubs/surv-manual/chpt07-measles.html
https://policylab.chop.edu/blog/how-measles-outbreaks-underscore-dangers-vaccine-hesitancy-200-words
https://www.cnn.com/2018/08/15/health/us-measles-cases-cdc/index.html
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5710408/
https://www.cdc.gov/immigrantrefugeehealth/profiles/somali/vaccine-hesitancy.html
https://www.cdc.gov/measles/cases-outbreaks.html
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