Since the introduction of vaccination, myths and misconceptions regarding vaccination have been present. Scientific research in psychology has shown that addressing these misconceptions is difficult: mere reading about a myth, even about a myth’s refutation, can strengthen the myth, rather than weaken its influence. Likewise, an explicit and strong negation of a risk can paradoxically increase rather than decrease the perception of risk in readers.
The steps outlined below, proposed in the scientific literature, aim to help public health professionals address vaccination misconceptions in the best possible way.
- Core facts: a refutation should always emphasize the facts, not the myth. The introduction should only present key facts easy to memorize.
- Explicit warnings: before any mention of a myth, text, visual or oral cues should clearly warn that the upcoming information is false.
- Alternative explanation: any knowledge gaps left by addressing misconceptions linked to vaccination should be filled by providing an alternative casual explanation for why the myth is false.
- Graphics: core facts should be displayed graphically when possible.
- Careful language: moderate language and formulations should always be used when saying that there is no risk as strong negations of risk may backfire and lead to a higher risk perception.
Measles is a serious disease
Vaccination is the best way to get immunity against measles
Vaccination is the only effective way to protect against measles
MMR vaccines combine three vaccinations in one and have an excellent safety record
MMR vaccination does not increase the risk of getting autism
Measles is a serious threat to health. Elimination of measles in Europe is endangered by non-vaccinated individuals
MEASLES IS A SERIOUS DISEASE
Introduction: In 1980, before measles vaccination was widely available, 2.6 million deaths were caused by measles globally each year . In 2012, still 122 000 people, mostly children, died from measles worldwide. : It is a common misperception that measles is a harmless disease. Some people further believe that the existing healthcare system in developed countries provides enough resources for good care when someone is infected with measles.: This misperception probably occurs due to the vaccination’s success: many people have never seen someone with measles infection and do not know how severe a measles infection can be. In fact, measles can be a severe infection, which cannot be directly treated with antivirals. Thus, once infected, only the symptoms such as high fever can be treated. Complications occur with about 30% of measles infections and can occur in almost every organ system . They range from ear infections, diarrhoea and related dehydration, to severe respiratory infections such as pneumonia and involve sequelae such as blindness or encephalitis (an infection that causes brain swelling) [1,2].
: In 1980, before measles vaccination was widely available, 2.6 million deaths were caused by measles globally each year . In 2012, still 122 000 people, mostly children, died from measles worldwide. Myth
: It is a common misperception that measles is a harmless disease. Some people further believe that the existing healthcare system in developed countries provides enough resources for good care when someone is infected with measles.Correction of the myth
: This misperception probably occurs due to the vaccination’s success: many people have never seen someone with measles infection and do not know how severe a measles infection can be. In fact, measles can be a severe infection, which cannot be directly treated with antivirals. Thus, once infected, only the symptoms such as high fever can be treated.
Complications occur with about 30% of measles infections and can occur in almost every organ system . They range from ear infections, diarrhoea and related dehydration, to severe respiratory infections such as pneumonia and involve sequelae such as blindness or encephalitis (an infection that causes brain swelling) [1,2].
Back to Top
Most measles-related deaths occur due to the complications associated with measles. Supportive care may only lower the probability of severe complications . Globally, more than 95% of measles deaths indeed occur in low-income countries with weak health infrastructures. However, measles-related deaths also occur in developed and industrialised European countries (e.g. between 2005 and 2013 there were 24 deaths in Bulgaria, 17 in Romania, 10 in France, 4 in Italy, 3 each in the UK and Germany ). Further, the number of hospitalisations due to measles is considerable (e.g. between 2005 and 2013 there were nearly or more than 20 000 hospitalisations in Ukraine, Romania and Bulgaria, 5 239 hospitalisations in France, 1 607 in the UK, 1 216 in Spain ).
Conclusion: Even though good healthcare can lower the probability of severe complications, measles-related deaths and hospitalisations due to complications occur even in developed and industrialised European countries.
→ Measles remains a serious disease. Vaccination is the only effective way to protect against it.
VACCINATION IS THE BEST WAY TO GET IMMUNITY AGAINST MEASLES
Introduction: MMR vaccines provide protection against measles, mumps and rubella without causing the development of severe symptoms, complications or sequelae that are associated with the diseases. Mild symptoms such as rash or fever may occur after vaccination in 3 to 5 of 100 individuals, as MMR is a live-attenuated vaccine. Measles is a severe infection, which cannot be treated with antivirals. Thus, once infected, only the symptoms can be treated. Complications of measles occur in 30% of the infections and can occur in almost every organ system  and involve sequelae such as blindness, encephalitis (an infection that causes brain swelling), severe diarrhoea and related dehydration, ear infections, or severe respiratory infections such as pneumonia [1,3]. Most measles-related deaths occur due to the complications.
Myth: It is a common myth that it is better to get immunity by getting the disease than by receiving the vaccine.
Correction of the myth: One reason why this misperception exists may be that natural immunity against measles, which is acquired through disease, gives life-long immunity while vaccination does not . However, it has been shown that a second dose of the vaccine does lead to a protective level of antibodies . Thus, two doses of MMR vaccine are recommended to reach immunity against measles.
Vaccinations elicit specific immune responses in the immune system, similar to the way an infection would, producing specific antibodies against the disease. Thus, an advantage of immunity through vaccination over immunity from the disease is that with vaccinations the organism is protected against the disease without developing severe symptoms, complications and sequelae.
Further, immunity through vaccination will protect others. Vaccination immunises the individual without enabling the individual to transmit the virus at any time. Immunity through the disease, however, exposes others to the risk of the disease before and during the time of infection. Measles is communicable four days before the first symptom appears. During this time, non-immune individuals may be infected and measles can spread.
Another reason why the myth exists may be the desire to avoid potential side effects from vaccination. Vaccinations, as every other pharmaceutical substance, do entail a certain probability of side effects , such as fever in 5–15 of 100 first doses or seizures in 1 of 3 000 first doses . More severe reactions occur only in single cases with incidences below 1 in 10 000. MMR vaccination thus has an excellent safety record and is therefore recommended by all EU countries.
The nature of human risk perception may also contribute to a preference for disease over the vaccine. A study showed that parents judged symptoms following vaccination as more severe than when the very same symptoms occurred during a disease  (see Figure). This bias occurs because humans tend to regret negative outcomes that result from their own actions more – because they feel guilty – than when the same outcomes occur due to inaction – because it’s fate. This effect can cause minor safety concerns to have disproportionately detrimental effects on vaccine uptake. Understanding this bias can help to make less biased decisions .
Conclusion: Vaccines provide protection against measles without the development of severe symptoms, complications or sequelae. Severe adverse events following MMR vaccination are very rare. It is therefore safer to vaccinate than to contract the disease. Further, immunity through vaccination will protect others while immunity through the disease exposes others to the risk of the disease before and during the time of infection. Thus, vaccination is the better and safer protection against measles.
→ Vaccination is the best and safest way to get immunity against measles.
Back to Top
VACCINATION IS THE ONLY EFFECTIVE WAY TO PROTECT AGAINST MEASLES
Introduction: MMR vaccination elicits specific responses in the immune system, similar to the way an infection would, producing antibodies against measles, mumps and rubella without developing severe symptoms, complications and sequelae.
Myth: It is a myth that homeopathy can be used as an alternative to vaccinations to protect children against measles. Some medical professionals following complementary and alternative methods are hesitant in recommending vaccination against measles and other childhood vaccinations  and propose homeopathic remedies as alternatives to vaccination.
Correction of the myth: Vaccinations, as every other pharmaceutical substance, entail a certain probability of side effects . Even though the side effects are usually mild, and more severe adverse events are very rare, this may lead to the desire of avoiding these side effects by using seemingly harmless homeopathic products instead, proposed to strengthen the immune system and thereby to protect against diseases without the risk of side effects. Yet, homeopathy is not entirely devoid of risk . Further, research has shown that the proposed mechanisms of homeopathy are implausible , and that homeopathic substances are ineffective [10, 13, 14]. Ostensible effects of homeopathic substances are equal to placebo effect, which means that effects occur due to mere expectations of the patients and not due to the substances themselves .
Beyond this, susceptible individuals who are exposed to the virus will contract measles with a probability of 90%, independent of the strength of their immune system. A person can only be protected against a measles infection by vaccination.
Conclusion: Homeopathy has been shown to be ineffective and based on implausible mechanisms. Substances that aim to strengthen the immune system in general will not prevent a susceptible individual from contracting measles.
→ Vaccination is the only effective way to protect against measles.
Back to Top
MMR VACCINES COMBINE THREE VACCINATIONS IN ONE AND HAVE AN EXCELLENT SAFETY RECORD
Introduction: Some combination vaccines contain multiple vaccines against different diseases, such as MMR vaccine, which contains vaccines against measles, mumps and rubella. This way, the organism is protected against different diseases with only one shot.
Myth: It is a common myth that giving a child the MMR combination vaccine increases the risk of harmful side effects and that it can overload the immune system.
Correction of the myth: This misperception is based on the idea that the more foreign substances enter the body, the stronger the immune system will be stressed. However, the myth that combination vaccines overload the immune system underestimates the power of the human immune system , and overestimates the number of foreign substance in multiple vaccines . The neonatal immune system develops even before birth . The immune system is capable of dealing with a very large number of antigens at the same time. In fact, every day foreign substances, e.g. in dust and dirt, trigger a child’s immune responses. A sore throat or a common cold exposes a child to more antigens than does the vaccine. The immune system is highly active. Other studies further show that vaccines do not weaken the immune system, as recently vaccinated children were equally likely to become infected from other pathogens as unvaccinated children [18–20].
Sometimes two or more injections with multiple vaccines are administered simultaneously in one visit (e.g. MMR with varicella or MMR with diphtheria-tetanus-pertussis (DTP)). Several studies have shown that both MMR alone and MMR simultaneously combined with certain other vaccines have an excellent safety record [17, 21–22]. If multiple vaccines would weaken the immune system one would expect lower immune responses than with individual applications of the vaccines [23, 24]. However, similar immune responses have been found when MMR vaccine was combined on the same day with vaccination against a) varicella [25, 26] or b) DTP, and oral poliovirus  or c) DTP-Hib (Haemophilus influenzae type b, and varicella  or d) with Hib .
Conclusion: The myth that combination vaccines overload the immune system underestimates the power of the human immune system, and overestimates the number of foreign substances in combination vaccines . The combination formula has an excellent safety record over many years.
→ The MMR vaccine, either applied alone or simultaneously with certain other vaccines, provides protection against many diseases at the same time and has an excellent safety record.
Back to Top
MMR VACCINATION DOES NOT INCREASE THE RISK OF GETTING AUTISM
Introduction: Since its introduction, around 575 million doses of MMR vaccine have been administered worldwide. It has an excellent safety record .
Myth: A common myth states, however, that MMR vaccination may cause autism.
Correction of the myth: This myth was born in England in 1998. A scientist suggested a link between the MMR vaccine and autism and gastrointestinal disease. His pledge to stop distributing the MMR vaccine received much media attention. In 2004 it was discovered that the scientist had financial interests in making this claim . A lawyer who intended to sue vaccine manufacturers hired him and recruited the children for the study. Moreover, the data was falsified: contrary to the reported onset of the symptoms after the vaccination, some of the children already showed symptoms before they were vaccinated. The original article was retracted by the journal . The fears caused by the flawed information led to years of lowered vaccine uptake, especially in the UK, with severe outbreaks as a consequence (see Figure). As a second consequence, numerous independent studies were conducted in many parts of the world to test the relationship between MMR vaccine and autism. All concluded that there is no such relationship [33-38].
Reasons why the myth is so persistent may be that the diagnosis of autism happens to fall into the period of time when, in most countries, MMR vaccination is recommended . This temporal contingency may give rise to a false sense of causality. Moreover, diagnoses of autism indeed increased by almost a factor of 10 (in the United States from 1976 to 1997 ) during the same period that the MMR vaccine was introduced. Along with explicit findings that show no relation between autism and vaccination, researchers conclude that the increase of diagnoses of autism is caused by ‘the introduction of broader, more precise diagnostic criteria, increased availability of services, and increased awareness of autism’ . When two rare events are salient (e.g. due to novelty or an increase in frequency), humans tend to perceive causality between the two events . This so-called illusory correlation is a typical cognitive bias  and may have contributed to the persistence of the myth.
Conclusion: A scientifically flawed journal article has wrongly caused fears that the MMR vaccine may lead to autism but numerous scientific articles shows refute this claim and show that no such relationship exists.
→ MMR vaccination does not increase the risk of getting autism.
Back to Top
MEASLES IS A SERIOUS THREAT TO HEALTH. ELIMINATION OF MEASLES IN EUROPE IS ENDANGERED BY NON-VACCINATED INDIVIDUALS
Introduction: In some regions of the world such as North and South America, measles has been eliminated .
Myth: It is a misconception however, that measles has been eliminated in Europe, and that therefore there is no reason to be vaccinated.
Correction of the myth: Overall, measles is rare in Europe and many people may have never seen a person infected with measles. This could explain why the myth exists. However, the myth that measles has been eliminated in Europe is wrong, for several reasons.
First, even though European countries have indeed committed to the goal of eliminating measles by 2015, measles elimination has not yet been reached. In many European regions, repeated outbreaks in unvaccinated communities occur, for example, since 2005 in Austria, Belgium, Bulgaria, Denmark, France, Italy, Spain, Romania, UK and Switzerland [43-50, 51]. Outbreaks lead to frequent hospitalisations and measles-related deaths: e.g. between 2005 and 2013 there were 24 deaths in Bulgaria, 17 in Romania, 10 in France, 3 each in Albania, the UK, and Germany, 2 each in Georgia and the Netherlands and one in Spain . Outbreaks occur due to pockets of susceptible individuals, who are not immune either due to omitted vaccinations, because the immune system failed to respond to the vaccine (this is rare) or because the individuals are too young or too ill to get vaccinated .
Second, measles occurs with even higher incidence rates in other parts of the world, e.g. Africa and Asia [52, 53]. Due to high global mobility viruses travel as humans do . High vaccination rates are therefore necessary to prevent measles from spreading. This can only be reached when 95% of the population is vaccinated with two doses of measles-containing vaccine .
Third, sudden omission of measles vaccination in a population can lead to dramatic increases of measles infections. This was seen, for example, in the UK following an unsubstantiated vaccine scare, which caused vaccine rates to drop and led to thousands of measles cases (see key message 5).
Vaccination against measles helps to protect the individual and protects others who may be not immune thanks to the so-called herd immunity: vaccination also stops the transmission of the disease and therefore indirectly protects non-immune individuals. For measles, a 95% vaccine coverage is needed for herd immunity to work. It is each individual’s responsibility to contribute to a safe and healthy environment for everyone.
Conclusion: Elimination of measles in Europe has not yet been achieved. It is endangered by non-vaccinated individuals and by high global mobility. Only if 95% of the population in all European countries is vaccinated with two doses of measles-containing vaccine, can elimination be reached. Until then, measles is a serious threat to health in Europe.
→ Measles is still a threat in Europe. Only with a 95% vaccine coverage, can elimination be reached.
Back to Top
Back to Top
3. Orenstein WA, Perry RT, Halsey NA. The clinical significance of measles: a review. J Infect Dis. 2004; 189(1): 4-16.
4. Christenson B, Böttiger M. Measles antibody: comparison of long-term vaccination titres, early vaccination titres and naturally acquired immunity to and booster effects on the measles virus. Vaccine. 1994;12(2):129-133.
5. Edwards IR, Aronson JK. Adverse drug reactions: definitions, diagnosis, and management. The Lancet. 2000; 356(9237):1255-1259.
7. Brown KF, Kroll JS, Hudson MJ, Ramsay M, Green J, Vincent CA, et al. Omission bias and vaccine rejection by parents of healthy children: implications for the influenza A/H1N1 vaccination programme. Vaccine. 2010 Jun;28:4181-4185.
8. Wroe AL, Turner N, Salkovskis PM. Understanding and predicting parental decisions about early childhood immunizations. Health Psychol. 2004;23(1):33.
9. Lehrke P, Nuebling M, Hofmann F, Stoessel U. Attitudes of homoeopathic physicians towards vaccination. Vaccine. 2001;19: 4859-64.
10. Stratton K, Ford A, Rusch E, Clayton EW. Adverse effects of vaccines: evidence and causality. National Academies Press; 2012.
11. Ernst E. Is homeopathy a clinically valuable approach? Trends Pharmacol Sci. 2005; 26(11):547-548.
12. Grimes DR. Proposed mechanisms for homeopathy are physically impossible. Focus Altern Complement Ther. 2012;17(3):149-155 .
13. Ernst E. A systematic review of systematic reviews of homeopathy. Br J Clin Pharmacol. 2002;54 (6): 577–82.
15. Shang A, Huwiler-Müntener K, Nartey L, Jüni P, Dörig S, Sterne JAC, et al. Are the clinical effects of homoeopathy placebo effects? Comparative study of placebo-controlled trials of homoeopathy and allopathy. The Lancet. 2005; 366(9487):726–732.
16. Abbas AK, Lichtman AH, Pober JS. Cellular and Molecular Immunology. 2nd ed. Philadelphia: WB Saunders Co; 1994.
17. Offit PA, Quarles J, Gerber MA, Hackett CJ, Marcuse EK, Kollman TR, et al. Addressing parents’ concerns: do multiple vaccines overwhelm or weaken the infant’s immune system?. Pediatrics. 2002; 109(1):124-129.
18. Black SB, Cherry J D, Shinefield HR, Fireman B, Christenson P, Lampert D. Apparent decreased risk of invasive bacterial disease after heterologous childhood immunization. Am J Dis Child. 1991;145:746–749.
19. Davidson M, Letson GW, Ward JI, Ball A, Bulkow L, Christenson P, et al. DTP immunization and susceptibility to infectious diseases. Is there a relationship? Am J Dis Child. 1991;145:750–754.
20. Storsaeter J, Olin P, Renemar B, Lagergard T, Norberg R, Romanus V, et al. Mortality and morbidity from invasive bacterial infections during a clinical trial of acellular pertussis vaccines in Sweden. Pediatr Infect Dis J. 1988;7:637–645.
21. Smith MJ, Woods CR. On-time vaccine receipt in the first year does not adversely affect neuropsychological outcomes. Pediatrics. 2010;125(6): 1134-1141.
22. Stratton KR, Wilson CB, McKormick MC. Immunization safety review: multiple immunizations and immune dysfunction. National Academies Press; 2002.
23. King GE, Hadler SC. Simultaneous administration of childhood vaccines: an important public health policy that is safe and efficacious. Pediatr Infect Dis J. 1994;13:394–407.
24. American Academy of Pediatrics. Combination vaccines for childhood immunization: recommendations of the Advisory Committee on Immunization Practices, the American Academy of Pediatrics, and the American Academy of Family Physicians. Pediatrics. 1999;103:1064–1077.
25. Englund JA, Suarez C, Kelly J, et al. Placebo-controlled trial of varicella vaccine given with or after measles-mumps-rubella vaccine. J Pediatr. 1989;114:37–44.
26. Brunell PA, Novelli VM, Lipton SV, Pollock B. Combined vaccine against measles, mumps, rubella, and varicella. Pediatrics. 1988;81:779–784.
27. Deforest A, Long SS, Lischner HW, Girone JAC, Clark JL, Srinivasan R, et al. Simultaneous administration of measles-mumps-rubella vaccine with booster doses of diphtheria tetanus pertussis and poliovirus vaccines. Pediatrics. 1988;81:237–246.
28. Shinefield HR, Black SB, Staehle BO, Adelman T, Ensor K, Ngai A, et al. Safety, tolerability, and immunogenicity of concomitant infections in separate locations of MMRII, Varivax and Tetramune in healthy children vs concomitant infection of MMRII and Tetramune followed six weeks later by Varivax. Pediatr Infect Dis J. 1998;17:980–985.
29. Dashefsky B, Wald E, Guerra N, Byers C. Safety, tolerability, and immunogenicity of concurrent administration of Haemophilus influenza type b conjugate vaccine (meningococcal protein conjugate) with either measles-mumps-rubella vaccine or diphtheria-tetanus-pertussis and oral poliovirus vaccines in 14- to 23-month-old infants. Pediatrics. 1990;85:682–689.
30. Lievano F, Galea SA, Thornton M, Wiedmann RT, Manoff S, Tran TN, Plotkin SA. Measles, mumps, and rubella virus vaccine (M–M–R™ II): A review of 32 years of clinical and postmarketing experience. Vaccine. 2012 Nov; 30(48):6918-26.
31. Deer B. Secrets of the MMR scare: How the vaccine crisis was meant to make money. BMJ. 2011; 342:c5258.
32. The Editors of The Lancet. Retraction—Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children.The Lancet. 2010 Feb; 375( 9713):445.
33. Fombonne E, Chakrabarti S. No evidence for a new variant of measles-mumps-rubella–induced autism. Pediatrics. 2001; 108(4): e58.
34. Taylor B, Miller E, Farrington CP, Petropoulos MC, Favot-Mayaud I, Li J, et al. Autism and measles, mumps, and rubella vaccine no epidemiological evidence for a causal association. The Lancet. 1999;353.
35. Peltola H, Patja A, Leinikki P, Valle M, Davidkin I, Paunio M. No evidence for measles, mumps, and rubella vaccine-associated inflammatory bowel disease or autism in a 14-year prospective study. The Lancet. 1998; 351:1327-1328.
36. Honda H, Shimizu Y, Rutter M. No effect of MMR withdrawal on the incidence of autism a total population study. J Child Psychol Psychiatry. 2005 Jun; 46(6):572-9.
37. Madsen KM, Hviid A, Vestergaard M, Schendel D, Wohlfahrt J, Thorsen P, Melbye, M. A population-based study of measles, mumps, and rubella vaccination and autism. N Engl J Med. 2002; 347(19): 1477-1482.
38. Hornig M, Briese T, Buie T, Bauman ML, Lauwers G, Siemetzki U, et al. Lack of association between measles virus vaccine and autism with enteropathy: a case-control study. PLoS One. 2008; 3(9):e3140.
39. Johnson CP, Myers SM. Identification and evaluation of children with autism spectrum disorders. Pediatrics. 2007; 120(5): 1183–215.
40. Barbaresi WJ, Katusic SK, Colligan RC, Weaver AL, Jacobsen SJ. The incidence of autism in Olmsted County, Minnesota, 1976-1997: results from a population-based study. Arch Pediatr Adolesc Med. 2005;159(1):37-44.
41. Hamilton DL, Gifford RK. Illusory correlation in interpersonal perception: A cognitive basis of stereotypic judgments. J Exp Soc Psychol. 1976; 12:392-407.
42. Istre GR, Mckee PA, West GR, O’Mara DJ, Rettig PJ, Stuemky J, et al. Measles spread in medical settings: an important focus of disease transmission?. Pediatrics. 1987;79(3):356-358.
43. Schmid D, Holzmann H, Schwarz K, Kasper S, Kuo HW, Aberle SW, et al. Measles outbreak linked to a minority group in Austria, 2008. Epidemiol Infect. 2010;138(3):415.
44. Lernout T, Kissling E, Hutse V, Schrijver KD, Top G. An outbreak of measles in orthodox Jewish communities in Antwerp, Belgium, 2007-2008: different reasons for accumulation of susceptibles. Euro Surveill. 2009;14(2).
45. Muscat M, Christiansen AH, Persson K, Plesner AM, Bottiger BE, Glismann S, et al. Measles outbreak in the Oresund region of Denmark and Sweden. Euro Surveill. 2006; 11(3):e060330.
46. Du Châtelet IP, Antona D, Freymuth F, Muscat M, Halftermeyer-Zhou F, Maine C, et al. Spotlight on measles 2010: Update on the ongoing measles outbreak in France, 2008-2010. Euro Surveill. 2010; 15(36):19656.
47. Van Treeck UV. Measles outbreak in Germany: over 1000 cases now reported in Nordrhein Westfalen. Euro Surveill. 2006;11(5):e060511.
48. Filia A, Curtale F, Kreidl P, Morosetti G, Nicoletti L, Perrelli F, et al. Cluster of measles cases in the Roma/Sinti population, Italy, June-September 2006. Euro Surveill. 2006; 11(10):e061012.
49. Perucha M, Ramalle-Gómara E, Lezaun ME, Blanco A, Quiñones C, Blasco M. A measles outbreak in children under 15 months of age in La Rioja, Spain, 2005-2006. Euro Surveill. 2006; 11(10):267.
50. Richard JL, Masserey-Spicher V. Ongoing measles outbreak in Switzerland: results from November 2006 to July 2007. Euro Surveill, 2007; 12(7), e070726.
52. World Health Organization Europe [Internet]. Centralized Information System For Infectious Diseases (CISID). Copenhagen: WHO Europe; 2014. Available online: http://data.euro.who.int/cisid
53. Marshall TM, Hlatswayo D, Schoub B. Nosocomial Outbreaks—A Potential Threat to the Elimination of Measles?. J Infect Dis. 2003; 187(1):97-101.
54. Brockmann D & Helbing D. The Hidden Geometry of Complex, Network-Driven Contagion Phenomena. Science, 342:1337-1342.