The complication is that the herd immunity can break down rather quickly when the vaccination uptake drops below 80-90% in these clusters. And all it takes is one person carrying a vaccine preventable disease from an area, where it is endemic, to then start an outbreak or epidemic very quickly in one of these low vaccine uptake clusters. For a disease like measles, which is very contagious, it jumps from an infected person to unvaccinated individuals quite rapidly, sometimes before public health authorities can contain it. Measles is easily prevented with the MMRV vaccine (which also protects children against mumps, rubella, and chickenpox).
In a recent article published in Pediatrics, researchers investigated a measles outbreak in Minnesota in 2011. The authors, lead by Pamala Gahr of the Minnesota Department of Health, determined that the outbreak began when an unvaccinated 2-year-old travelled to Kenya, where he contracted the measles virus. Upon returning to the United States, the child developed a fever, cough and vomiting, some of the early signs and symptoms of measles. Unfortunately, prior to a diagnosis of measles, the child passed the virus on to three children in a child day-care center and another household member. The measles then spread from individual to individual within a low vaccine uptake area, a Somali immigrant community in the Minneapolis area. Eventually, more than 3,000 people were exposed to the disease.
According to the researchers, 21 cases of measles were identified. Of those, 16 individuals were not vaccinated, of whom 9 were age-eligible to be vaccinated with the MMRV (or MMR) vaccine. Of those nine children who were unvaccinated and contracted measles, seven were not vaccinated because of parental safety concerns. Gahr stated that this was consistent with a striking decline in MMR accept ache among Minnesota's large Somali population. For example, in 2004, over 90% of Somali children in Minnesota were on schedule with the MMR vaccines. By 2010, that rate had dropped to 54%.
I want to reiterate a small point, because it keeps showing up on the zombie tropes of the antivaccination crowd. Sixteen out of the 21 individuals who contract the measles virus were not vaccinated.
Even though the number of cases was relatively small, only 21, it was the largest outbreak in Minnesota in over 20 years. What's worse, many individuals thought that measles had been defeated in the USA (and it probably still isn't endemic to the country).
The Somali community in Minnesota is around 20-60 thousand, with many immigrants coming to Minnesota in the 1990's. Although the group is made up less of Somali-born individuals, and more US-born, many travel to Somalia and other nearby areas where measles is endemic. With the low vaccine uptake in this insular community, diseases contracted outside of the USA could get a toehold in this part of Minnesota. Measles is bad enough, but the situation could be worse someone brings back polio or some other vaccine preventable disease to the community.
Sadly, it appears that the thoroughly discredited nonsense from Mr. Andy Wakefield, who claimed that the MMR or MMRV vaccine caused autism, has taken root in the Somali community. Let's be clear about Andy Wakefield's lies about the MMR vaccine and autism. The Lancet, which first published Wakefield's paper, retracted it. The British Medical Journal, a respected peer-reviewed publication, and an investigative writer, Brian Deer, wrote about Wakefield's deceit and fraud, here, here, and here. And there are literally hundreds of peer-reviewed articles that thoroughly dismiss any link between vaccines and autism. Is this clear? If only I could convince Minnesota's Somali community to read all of these links.
Furthermore, I know there's a subset of people, especially in the antivaccination cult, who are convinced that measles is not that dangerous. But it actually is quite serious, especially if it broke out and spread before public health officials could contain it. According to the US Centers for Disease Control and Prevention, the complications of measles are serious:
- About 30% of measles cases develop one or more complications, including pneumonia, which is the complication that is most often the cause of death in young children.
- Ear infections occur in about 1 in 10 measles cases and permanent loss of hearing can result.
- Diarrhea is reported in about 8% of cases.
- These complications are more common among children under 5 years of age and adults over 20 years old.
- As many as 1 out of every 20 children with measles gets pneumonia
- About 1 child in every 1,000 who get measles will develop encephalitis. (This is an inflammation of the brain that can lead to convulsions, and can leave the child deaf or with a neurodevelopmental disorder.)
- For every 1,000 children who get measles, 1 or 2 will die from it.
- Measles also can make a pregnant woman have a miscarriage, give birth prematurely, or have a low-birth-weight baby.
Vaccine deniers constantly attempt to use anecdotes to claim "I don't remember measles being anything more than a rash." That's because, unless you're in your late 50's, vaccinations against measles prevented most outbreaks. Yes most kids who catch measles will show no complications. But it's the 30% who do have complications, and the 2 out of 1,000 who die, that are going to be noticed in a large outbreak. And it will be sad if it is one of your children. And remember, this disease can be transmitted to children who are too young to be vaccinated, so it can harm families who actually want to vaccinate their children. They may pay the ultimate price of a antivaccination caused epidemic.
Vaccinate your children against measles. It's the right thing to do. Because measles shouldn't be making a comeback in this modern world with modern medicine. It is a disease from a different time and era, something that my grandparents suffered, and not my children.
- Retraction--Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet. 2010 Feb 6;375(9713):445. doi: 10.1016/S0140-6736(10)60175-4. PubMed PMID: 20137807.
- Gahr P, DeVries AS, Wallace G, Miller C, Kenyon C, Sweet K, Martin K, White K, Bagstad E, Hooker C, Krawczynski G, Boxrud D, Liu G, Stinchfield P, LeBlanc J, Hickman C, Bahta L, Barskey A, Lynfield R. An Outbreak of Measles in an Undervaccinated Community. Pediatrics. 2014 Jun 9. pii: peds.2013-4260. [Epub ahead of print] PubMed PMID: 24913790.
- Helmecke MR, Elmendorf SL, Kent DL, Pauze DK, Pauze DR. Measles investigation: A moving target. Am J Infect Control. 2014 Jun 14. pii: S0196-6553(14)00735-4. doi: 10.1016/j.ajic.2014.04.024. [Epub ahead of print] PubMed PMID: 24939517.