Disneyland measles outbreak

Disneyland measles outbreak
Disneyland measles outbreak
	Young boy with measles
Disease	Measles
Virus strain	Measles morbillivirus
Location	United States, Mexico, Canada
First outbreak	December 2014
First reported	January 5, 2015
Index case	Unidentified
Confirmed cases	131 in California; 16 in other US states; 159 in one Canadian community; One in Mexico;
Hospitalized cases	10–20% of affected
Deaths	None
Vaccinations	Measles vaccine

Last updated December 20, 2023

The Disneyland measles outbreak began at the Disneyland Resort, California, in December 2014, and spread to seven states in the United States, Mexico, and Canada, before it was declared over in mid-April 2015.

The first case of measles was reported on January 5, 2015, in an unvaccinated 11-year-old Californian resident. Between December 2014 and March 2015, 131 Californians were infected, with almost 90% of cases occurring in southern California. Linked to the California cases were 16 cases in six other US states, 159 cases in a religious group in Québec, Canada, and one case in Mexico. Almost all the Canadian cases were unvaccinated. The source of the initial Disney theme park exposure was not identified, but specimens from several cases matched with the recent measles outbreak in the Philippines.

It triggered an international debate on vaccine hesitancy, particularly as it had spread to people who intentionally declined the vaccine and put vulnerable people who could not have the vaccine at risk. The outbreak prompted the California Senate Bill 277, laws that reverted the California personal belief vaccine exemption. Conclusions following examination of the outbreak pointed to undervaccination as a key cause.

Background

According to the Centers for Disease Control (CDC), the measles was a virus nearly all children obtained by the age of 15.^[1] There was an effort to make a vaccine against the measles that had success.^[1] Two doses of the measles vaccine provides 97%^[2] to 99%^[3] protection from acquiring the disease. Prevention of a measles outbreak requires around 95% of a population to be vaccinated with two doses of a measles vaccine.^[2]^[4] The few remaining that are unvaccinated or have not mounted an immune response from the measles vaccine, are protected by herd immunity.^[3]^[4]^[5]^{[lower-alpha 1]}

In 2000, the US declared measles as eliminated due to an effective vaccination programme and public health response systems.^[6] Prior to the Disneyland measles outbreak of 2014–15, California saw increasing rates of non-medical vaccine exemptions, sometimes in clusters which left those communities susceptible to measles.^[4] Vaccine coverage at a quarter of California schools, including several around the Disneyland theme park, was too low for herd immunity.^[4] At the time, the Californian Disney theme parks received 24 million visitors a year.^[7]

Outbreak

On January 5, 2015, the California Department of Public Health (CDPH) first heard of a case of measles in a hospitalised 11-year old Californian resident whose rash started on December 28, 2014, and who had visited one of two neighbouring Californian Disney theme parks.^[3]^[7] Four more cases were reported on the same day, and all had visited the Disney theme parks between December 17 and 20.^[7] CDPH issued a press release on January 7, 2015, by which time there were seven cases.^[7]

By February 11, 2015, the Centers for Disease Control and Prevention (CDC) attributed 125 cases of measles across seven US states, 110 of which were in California, to the outbreak.^[4]^[7] 39 of the California cases had visited the Disney parks between December 17 and 20, and 34 were secondary contacts.^[7] Of the other 15 cases linked to the Disneyland outbreak, seven were in Arizona, one in Colorado, one in Nebraska, one in Oregon, three in Utah, and two in Washington.^[7]^[8] Cases linked to the outbreak were reported in Mexico, and in Canada its Public Health Agency reported more than 150 cases of measles that were linked to one imported case from the Disneyland outbreak.^[4] Of the 110 Californian cases by February 2015, at least 13 were vaccinated against the measles, 1 had had prior infection or vaccination, and at least 49 were unvaccinated, 28 of whom held anti-vaccine beliefs.^[9] 12 cases, included in the unvaccinated total, occurred in infants too young to have the vaccine; they relied on herd immunity for protection.^[4] The remaining 47 had unknown or undocumented vaccination status.^[7] Almost all the Canadian cases were unvaccinated.^[4] Some cases occurred in people who had been vaccinated with two doses of the measles vaccine.^[5]

Between December 2014 and March 2015, 131 Californians were infected, with almost 90% of cases occurring in southern California.^[10] Linked to the California cases were 16 cases in six other US states, 159 cases in a religious group in Québec, Canada, and one case in Mexico.^[10] The outbreak was declared over in mid-April 2015.^[4] Conclusions following examination of the outbreak pointed to undervaccination as a key explanation.^[4] The source of the initial Disney theme park exposure was not identified, but specimens from several cases matched with the recent measles outbreak in the Philippines, but was also detected in at least 14 countries.^[7]

Contact tracing was implemented by local health agencies.^[10] To encourage vaccination, Roald Dahl's 1986 "Measles: A dangerous illness" open letter was recirculated as a result of the outbreak.^[11] The incident prompted the California Senate Bill 277, laws that reverted the California personal belief vaccine exemption.^[9]^[12]

Reaction and aftermath

Many people thought of measles as a disease of the past, and the Disneyland outbreak came as a surprise to them.^[6] It triggered an international debate on vaccine hesitancy, particularly as it had spread to people who intentionally declined the vaccine and put vulnerable people who could not have the vaccine, at risk.^[4] Headlines included "The good thing about the Disney measles outbreak", "Finally, California lawmakers say vaccination is a social responsibility", and "Oregon legislator wants to eliminate 'philosophical' vaccine exemption".^[6] One website reported "Mickey Mouse Gets the Measles" and one blog wrote "Space Mountain with a Side of Measles” and "Measles was not the name of an eighth 'Snow White' dwarf".^[13] Media coverage and social media posts focused on the harms of the "anti-vaxx" movement and resulted in a positive influence in vaccine uptake and the effect was dubbed by some as the "Disneyland effect".^[4] The term measles had its highest level of hits on Google Trends in over 10 years.^[4] National US surveys showed that more than half the population knew about the outbreak.^[4] Among Twitter users, the most common retweet was a post of a Forbes news article that described the outbreak as a "turning point in the vaccine wars."^[4] It argued that people generally wished to defend vaccination, although others doubted it.^[4]

Several studies subsequently looked at the effect of the Disneyland outbreak on people's views about vaccination.^[4] There was little inconsistency; a larger proportion of people reported more positive views towards vaccination.^[4] One study reported that a third of mothers showed more interest in the measles vaccine, another revealed that more than a third of pediatricians said that they had fewer requests for vaccine alternatives schedules, and a fifth reported stricter policies in vaccinating.^[4] Parents with higher educational levels felt more favourable towards vaccines in some studies, and one study reported more positive views towards vaccines in the white population and in those with higher incomes.^[4] Effect varied by population subgroup.^[4] Media coverage had likely encouraged favorable vaccine-related beliefs.^[4]

Between January 1 and December 31, 2019, 1,282 cases of measles were confirmed in 31 US states.^[14] One case that year was a person who visited Disneyland.^[15]

Footnotes

↑ Looking at measles outbreaks in the 1980s, 65% were noted to have a first measles vaccine and analysis of the findings concluded that a failure to mount an immune response occurred in 4% of those vaccinated.^[3]

Related Research Articles

Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating the body's adaptive immunity, they help prevent sickness from an infectious disease. When a sufficiently large percentage of a population has been vaccinated, herd immunity results. Herd immunity protects those who may be immunocompromised and cannot get a vaccine because even a weakened version would harm them. The effectiveness of vaccination has been widely studied and verified. Vaccination is the most effective method of preventing infectious diseases; widespread immunity due to vaccination is largely responsible for the worldwide eradication of smallpox and the elimination of diseases such as polio and tetanus from much of the world. However, some diseases, such as measles outbreaks in America, have seen rising cases due to relatively low vaccination rates in the 2010s – attributed, in part, to vaccine hesitancy. According to the World Health Organization, vaccination prevents 3.5–5 million deaths per year.

<span class="mw-page-title-main">Measles</span> Viral disease affecting humans

Measles is a highly contagious, vaccine-preventable infectious disease caused by measles virus. Symptoms usually develop 10–12 days after exposure to an infected person and last 7–10 days. Initial symptoms typically include fever, often greater than 40 °C (104 °F), cough, runny nose, and inflamed eyes. Small white spots known as Koplik's spots may form inside the mouth two or three days after the start of symptoms. A red, flat rash which usually starts on the face and then spreads to the rest of the body typically begins three to five days after the start of symptoms. Common complications include diarrhea, middle ear infection (7%), and pneumonia (6%). These occur in part due to measles-induced immunosuppression. Less commonly seizures, blindness, or inflammation of the brain may occur. Other names include morbilli, rubeola, red measles, and English measles. Both rubella, also known as German measles, and roseola are different diseases caused by unrelated viruses.

Herd immunity is a form of indirect protection that applies only to contagious diseases. It occurs when a sufficient percentage of a population has become immune to an infection, whether through previous infections or vaccination, thereby reducing the likelihood of infection for individuals who lack immunity.

Vaccine hesitancy is a delay in acceptance, or refusal, of vaccines despite the availability of vaccine services and supporting evidence. The term covers refusals to vaccinate, delaying vaccines, accepting vaccines but remaining uncertain about their use, or using certain vaccines but not others. The scientific consensus that vaccines are generally safe and effective is overwhelming. Vaccine hesitancy often results in disease outbreaks and deaths from vaccine-preventable diseases. Therefore, the World Health Organization characterizes vaccine hesitancy as one of the top ten global health threats.

Vaccination and religion have interrelations of varying kinds. No major religion prohibits vaccinations, and some consider it an obligation because of the potential to save lives. However, some people cite religious adherence as a basis for opting to forego vaccinating themselves or their children. Many such objections are pretextual: in Australia, anti-vaccinationists founded the Church of Conscious Living, a "fake church", leading to religious exemptions being removed in that country, and one US pastor was reported to offer vaccine exemptions in exchange for online membership of his church.

A breakthrough infection is a case of illness in which a vaccinated individual becomes infected with the illness, because the vaccine has failed to provide complete immunity against the pathogen. Breakthrough infections have been identified in individuals immunized against a variety of diseases including mumps, varicella (Chickenpox), influenza, and COVID-19. The characteristics of the breakthrough infection are dependent on the virus itself. Often, infection of the vaccinated individual results in milder symptoms and shorter duration than if the infection were contracted naturally.

Claims of a link between the MMR vaccine and autism have been extensively investigated and found to be false. The link was first suggested in the early 1990s and came to public notice largely as a result of the 1998 Lancet MMR autism fraud, characterised as "perhaps the most damaging medical hoax of the last 100 years". The fraudulent research paper authored by Andrew Wakefield and published in The Lancet falsely claimed the vaccine was linked to colitis and autism spectrum disorders. The paper was retracted in 2010 but is still cited by anti-vaxxers.

A vaccination policy is a health policy adopted in order to prevent the spread of infectious disease. These policies are generally put into place by State or local governments, but may also be set by private facilities, such as workplaces or schools. Many policies have been developed and implemented since vaccines were first made widely available.

Health may refer to "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity.", according to the World Health Organization (WHO). 78.7 was the average life expectancy for individuals at birth in 2017. The highest cause of death for United States citizens is heart disease. Sexually transmitted infections impact the health of approximately 19 million yearly. The two most commonly reported infections include chlamydia and gonorrhea. The United States is currently challenged by the COVID-19 pandemic, and is 19th in the world in COVID-19 vaccination rates. All 50 states in the U.S. require immunizations for children in order to enroll in public school, but various exemptions are available by state. Immunizations are often compulsory for military enlistment in the United States.

Measles vaccine protects against becoming infected with measles. Nearly all of those who do not develop immunity after a single dose develop it after a second dose. When rate of vaccination within a population is greater than 92%, outbreaks of measles typically no longer occur; however, they may occur again if the rate of vaccination decrease. The vaccine's effectiveness lasts many years. It is unclear if it becomes less effective over time. The vaccine may also protect against measles if given within a couple of days after exposure to measles.

Robert William Sears, known as Dr. Bob, is an American pediatrician from Capistrano Beach, California, noted for his unorthodox and dangerous views on childhood vaccination. While Sears acknowledges the efficacy of vaccines—for instance, he supports the claim that Chicken pox, measles, whooping cough, polio, diphtheria have all disappeared because of vaccines—he has proposed alternative vaccination schedules that depart from accepted medical recommendations. His proposals have enjoyed celebrity endorsement but are not supported by medical evidence and have contributed to dangerous under-vaccination in the national child population. While he denies being anti-vaccine, Sears has been described by many as anti-vaccine and as a vaccine delayer.

Measles is extremely contagious, but surviving the infection results in lifelong immunity, so its continued circulation in a community depends on the generation of susceptible hosts by birth of children. In communities which generate insufficient new hosts the disease will die out. This concept was first recognized by Bartlett in 1957, who referred to the minimum number supporting measles as the critical community size (CCS). Analysis of outbreaks in island communities suggested that the CCS for measles is c. 250,000. Due to the development of vaccination against measles, the world has seen a 99% decrease in measles related cases compared cases before the vaccine was developed.

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<i>Melanies Marvelous Measles</i> Anti-vaccine book with dangerous message that contracting the measles is beneficial

Melanie's Marvelous Measles is a self-published children's book written by Australian author and anti-vaccine activist Stephanie Messenger. Through its story, the book claims, contrary to scientific data, that contracting measles is beneficial to health, and that vaccines are ineffective.

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References

1 2 "History of Measles". November 5, 2020.
1 2 Vesikari, Timo; Usonis, Vytautas (2021). "9. Measles-Mumps-Rubella vaccine". In Vesikari, Timo; Damme, Pierre Van (eds.). Pediatric Vaccines and Vaccinations: A European Textbook (Second ed.). Switzerland: Springer. pp. 80–89. ISBN 978-3-030-77172-0.
1 2 3 4 Suryadevara, Manika (2021). "36. Vaccine-preventable disease outbreaks". In Domachowske, Joseph; Suryadevara, Manika (eds.). Vaccines: A Clinical Overview and Practical Guide. Switzerland: Springer. pp. 419–439. ISBN 978-3-030-58416-0.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Doll, Margaret K.; Correira, John W. (November 2, 2021). "Revisiting the 2014–15 Disneyland measles outbreak and its influence on pediatric vaccinations". Human Vaccines & Immunotherapeutics. 17 (11): 4210–4215. doi:10.1080/21645515.2021.1972707. ISSN 2164-554X. PMC 8828106 . PMID 34495822. S2CID 237455828.
1 2 Palmer, Katie M. (January 26, 2015). "Why Did Vaccinated People Get Measles at Disneyland? Blame the Unvaccinated". Wired. Archived from the original on February 10, 2022. Retrieved February 10, 2022.
1 2 3 Auger, Giselle A. (2016). "11. Public interest communication and polarized issues". In Brunner, Brigitta R. (ed.). The Moral Compass of Public Relations. New York & London: Routledge. pp. 163–164. ISBN 978-1-138-12154-6.
1 2 3 4 5 6 7 8 9 Zipprich, Jennifer; Winter, Kathleen; Hacker, Jill; Xia, Dongxiang; Watt, James; Harriman, Kathleen (February 20, 2015). "Measles outbreak — California, December 2014 – February 2015". MMWR. Morbidity and Mortality Weekly Report. 64 (6): 153–154. ISSN 1545-861X. PMC 4584705 . PMID 25695321.
↑ Rozbicki, Melanie (September 1, 2016). "It's a Small World After All: Dealing with the Aftermath of the Disneyland Measles Outbreak" . Journal of Biosecurity, Biosafety, and Biodefense Law. 7 (1): 133–153. doi:10.1515/jbbbl-2016-0005. ISSN 2154-3186. S2CID 79450276.
1 2 Dykes, Brent (2019). "2. Why tell stories with data?". Effective Data Storytelling: How to Drive Change with Data, Narrative and Visuals. Hoboken, new Jersey: John Wiley & Sons. pp. 42–43. ISBN 978-1-119-61571-2.
1 2 3 Worden, Lee; Ackley, Sarah F.; Zipprich, Jennifer; Harriman, Kathleen; Enanoria, Wayne T. A.; Wannier, Rae; Porco, Travis C. (March 2020). "Measles transmission during a large outbreak in California". Epidemics. 30: 100375. doi:10.1016/j.epidem.2019.100375. ISSN 1878-0067. PMC 7211428 . PMID 31735584.
↑ Cawkwell, Philip B.; Oshinsky, David (March 1, 2016). "Storytelling in the context of vaccine refusal: a strategy to improve communication and immunisation" . Medical Humanities. 42 (1): 31–35. doi:10.1136/medhum-2015-010761. ISSN 1468-215X. PMID 26438615. S2CID 32611632.
↑ DeDominicis, Kali; Buttenheim, Alison M.; Howa, Amanda C.; Delamater, Paul L.; Salmon, Daniel; Omer, Saad B.; Klein, Nicola P. (December 2020). "Shouting at each other into the void: A linguistic network analysis of vaccine hesitance and support in online discourse regarding California law SB277". Social Science & Medicine. 266: 113216. doi: 10.1016/j.socscimed.2020.113216 . ISSN 1873-5347. PMID 33126093. S2CID 225202630.
↑ Sharfstein, Joshua M. (April 21, 2015). "Of mouse and measles". JAMA. 313 (15): 1504–1505. doi: 10.1001/jama.2015.1135 . ISSN 1538-3598. PMID 25898033.
↑ "Measles Cases and Outbreaks". Centers for Disease Control and Prevention. February 4, 2022. Archived from the original on February 9, 2022. Retrieved February 8, 2022.
↑ Hassan, Adeel (October 23, 2019). "Disneyland Visitor With Measles May Have Exposed Hundreds to Infection". The New York Times. Archived from the original on February 9, 2022. Retrieved February 8, 2022.

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[6] Looking at measles outbreaks in the 1980s, 65% were noted to have a first measles vaccine and analysis of the findings concluded that a failure to mount an immune response occurred in 4% of those vaccinated.^[3]

[:0-1] 1 2 "History of Measles". November 5, 2020.

[Vesikari2021-2] 1 2 Vesikari, Timo; Usonis, Vytautas (2021). "9. Measles-Mumps-Rubella vaccine". In Vesikari, Timo; Damme, Pierre Van (eds.). Pediatric Vaccines and Vaccinations: A European Textbook (Second ed.). Switzerland: Springer. pp. 80–89. ISBN 978-3-030-77172-0.

[Domachowske2021-3] 1 2 3 4 Suryadevara, Manika (2021). "36. Vaccine-preventable disease outbreaks". In Domachowske, Joseph; Suryadevara, Manika (eds.). Vaccines: A Clinical Overview and Practical Guide. Switzerland: Springer. pp. 419–439. ISBN 978-3-030-58416-0.

[Doll2021-4] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Doll, Margaret K.; Correira, John W. (November 2, 2021). "Revisiting the 2014–15 Disneyland measles outbreak and its influence on pediatric vaccinations". Human Vaccines & Immunotherapeutics. 17 (11): 4210–4215. doi:10.1080/21645515.2021.1972707. ISSN 2164-554X. PMC 8828106 . PMID 34495822. S2CID 237455828.

[Palmer2015-5] 1 2 Palmer, Katie M. (January 26, 2015). "Why Did Vaccinated People Get Measles at Disneyland? Blame the Unvaccinated". Wired. Archived from the original on February 10, 2022. Retrieved February 10, 2022.

[Brunner2016-7] 1 2 3 Auger, Giselle A. (2016). "11. Public interest communication and polarized issues". In Brunner, Brigitta R. (ed.). The Moral Compass of Public Relations. New York & London: Routledge. pp. 163–164. ISBN 978-1-138-12154-6.

[Zipprich-8] 1 2 3 4 5 6 7 8 9 Zipprich, Jennifer; Winter, Kathleen; Hacker, Jill; Xia, Dongxiang; Watt, James; Harriman, Kathleen (February 20, 2015). "Measles outbreak — California, December 2014 – February 2015". MMWR. Morbidity and Mortality Weekly Report. 64 (6): 153–154. ISSN 1545-861X. PMC 4584705 . PMID 25695321.

[Rozbicki2016-9] Rozbicki, Melanie (September 1, 2016). "It's a Small World After All: Dealing with the Aftermath of the Disneyland Measles Outbreak" . Journal of Biosecurity, Biosafety, and Biodefense Law. 7 (1): 133–153. doi:10.1515/jbbbl-2016-0005. ISSN 2154-3186. S2CID 79450276.

[Dykes2019-10] 1 2 Dykes, Brent (2019). "2. Why tell stories with data?". Effective Data Storytelling: How to Drive Change with Data, Narrative and Visuals. Hoboken, new Jersey: John Wiley & Sons. pp. 42–43. ISBN 978-1-119-61571-2.

[Worden2020-11] 1 2 3 Worden, Lee; Ackley, Sarah F.; Zipprich, Jennifer; Harriman, Kathleen; Enanoria, Wayne T. A.; Wannier, Rae; Porco, Travis C. (March 2020). "Measles transmission during a large outbreak in California". Epidemics. 30: 100375. doi:10.1016/j.epidem.2019.100375. ISSN 1878-0067. PMC 7211428 . PMID 31735584.

[Cawkwell2016-12] Cawkwell, Philip B.; Oshinsky, David (March 1, 2016). "Storytelling in the context of vaccine refusal: a strategy to improve communication and immunisation" . Medical Humanities. 42 (1): 31–35. doi:10.1136/medhum-2015-010761. ISSN 1468-215X. PMID 26438615. S2CID 32611632.

[DeDom2020-13] DeDominicis, Kali; Buttenheim, Alison M.; Howa, Amanda C.; Delamater, Paul L.; Salmon, Daniel; Omer, Saad B.; Klein, Nicola P. (December 2020). "Shouting at each other into the void: A linguistic network analysis of vaccine hesitance and support in online discourse regarding California law SB277". Social Science & Medicine. 266: 113216. doi: 10.1016/j.socscimed.2020.113216 . ISSN 1873-5347. PMID 33126093. S2CID 225202630.

[Sharfstein2015-14] Sharfstein, Joshua M. (April 21, 2015). "Of mouse and measles". JAMA. 313 (15): 1504–1505. doi: 10.1001/jama.2015.1135 . ISSN 1538-3598. PMID 25898033.

[CDC2019-15] "Measles Cases and Outbreaks". Centers for Disease Control and Prevention. February 4, 2022. Archived from the original on February 9, 2022. Retrieved February 8, 2022.

[Hassan2019-16] Hassan, Adeel (October 23, 2019). "Disneyland Visitor With Measles May Have Exposed Hundreds to Infection". The New York Times. Archived from the original on February 9, 2022. Retrieved February 8, 2022.

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