In a recent bacterial pathogenesis lecture, my class was shown a short video on whooping cough, a sometimes-fatal childhood disease caused by the bacteria Bordetella pertussis. Children no older than 2 years old were unable to breathe, taking desperate breaths in between painful coughing fits, mucus covering their faces. We had been studying the creation of ideal vaccines with the pertussis vaccine as an example. After the video, our professor mentioned in passing that an outbreak of whooping cough had occurred in Britain due to parents opting not to vaccinate their children because of a possible but rare link between the whole cell pertussis vaccine and neurological disease in infants. She went on to dismiss such a link as being scientifically improbable and most likely due to coincidence. I was also sceptical of this “anti-vaccine” train of thought: what caring parent would want to put their child through such a painful and frequently fatal condition as whooping cough, when it could be prevented?
As a biology student, vaccines were something I simply believed in, one of the modern miracles of science. Edward Jenner and Louis Pasteur, pioneers in the field of vaccination, were people to immortalize. But I have recently realized that it is a far cry from Jenner inoculating a boy with cowpox and creating immunological resistance against small pox, to the battery of up to six vaccines recommended by the Public Health Agency of Canada for infant immunization at 2, 4 and 6 months.
The idea of an anti-vaccine movement interested me in the same way Creationism interests an evolutionary biologist. Who were these strange people contesting the tried and true method of vaccination? After browsing many anti-vaccine websites, I was left with an uneasy feeling; the overwhelming majority of authors of these websites were either parents or doctors who believed their babies/patients had suffered vaccine-induced disease. In fact, a majority of the websites were persuasive and any expectant parent reading the articles could easily think twice about immunization plans. I will attempt to make some sense of the anti-vaccine movement, and discuss whether or not there is justification in overturning existing vaccination programs for infants.
The immune system of infants is more susceptible to infection than other children and adults. Under the age of 2 years, infant immune systems cannot make antibodies against pathogens without “helper” signals from a class of immune cells called T-cells. The significance of this is that the immune system will not recognize any bacteria or virus whose pathogenicity is determined by polysaccharides, because they are not recognized by the T-cells. Older children and adults are able to make T-cell independent responses, allowing them to have natural immunity to a range of potentially dangerous pathogens that infants do not have. This immaturity of infant immune systems is one reason for such early vaccinations strategies.
The current recommended immunization strategy for infants in Canada consists of the following vaccines: DTaP (diphtheria, tetanus, acellular pertussis), IPV (inactivated poliovirus), Hib (Haemophilus influenzae type b conjugate), MMR (measles, mumps and rubella), Hep B (hepatitis B), V (varicella), PC (pneumococcal conjugate), MC (meningococcal C conjugate), according to the following schedule:
Even at a cursory glance, this schedule seems an excessive burden to put on a developing child, despite the apparent necessity. These vaccines will contain one or more of: bacterial/viral proteins or polysaccharide/protein conjugates, killed or avirulent bacteria and viruses, preservatives, antibiotics, and adjuvants (a substance that will enhance immune response). Induction of such bacterial, viral and chemical materials into an infant is intuitively unnatural, but because of the developing nature of babies and the limits of animal models (in relation to humans), it is extremely difficult to ascertain any adverse reactions of the vaccines.
Two of the main anti-vaccine or vaccine awareness groups in Canada and the US are VRAN (Vaccine Awareness Risk Network) and NVIC (National Vaccine Information Center), respectively. Both groups promote informed choice in vaccination, and display a variety of information regarding the perceived risk of infant vaccination programs. The primary diseases and conditions these groups attribute to vaccination include: SIDS (Sudden Infant Death Syndrome) and general anaphylaxis (both as a general response to vaccination); neurological disorders (general response to vaccination; particularly whole cell pertussis); autism (in association with the MMR vaccine) and diabetes (response to Hib mainly), in addition to others.
The main descriptors of vaccine-induced disease that are presented by anti-vaccine groups are individual case studies as observed by parents or paediatricians. In the case of anaphylaxis, SIDS, and encephalitis, cases are well described of infants who are born healthy and suddenly experience seizures, fevers and lack of response hours or days after each vaccination (2,4,6 months, etc.). The majority of children described were later diagnosed with an otherwise unexplained neurological disease. These stories are both too numerous and compelling to be ignored, but are observational rather than scientific; there’s no direct physical link to attribute the vaccine to the child’s reaction.
In addition to personal testimonials, there are articles written by a number of doctors, but the articles tend to be general, with few references and are not peer-reviewed. The shortcoming in this again is that there is little scientific evidence to verify the theoretical arguments. One argument presented is that vaccines contain toxic substances that negatively influence the growing stage of the brain. Obviously a toxin can affect the development of the brain, but the linkage from the site of inoculation to the nervous system is not described. Another argument points to the inherent connection of the immune and nervous systems, and cites the over-stimulation of the immune system in response to vaccines (and adjuvants) as again detrimental to brain development. Again the specifics of this relationship are not explained.
In contrast to the information presented by VRAN and NVIC, the large majority of scientific studies show no causal relationship between any vaccine and disease. Afzal, et al. found no correlation between the MMR vaccine and autism; DeStefano, et al. showed no causal relationship between diabetes and the Hib vaccine, and in a general study, Fleming, et al. found no link between immunization and SIDS. The weakness in most of these studies is that they are comparative association studies; incidences of disease are compared with vaccination schedules. This takes into account the overall population, but does not take into account the physical or personal evidence of each individual.
Government agencies exist in both Canada and the US for the recording of adverse reaction to vaccines. In a summary of the reports from the US agency VAERS (Vaccine Adverse Event Reporting System) from 1991-2001, 11.4 adverse events per 100,000 were reported, the most common event being fever. Of the total number reported, 14.2% were described as serious adverse events (including death, life-threatening illness, hospitalization, permanent disability). This means that about 1.6 out of 100,000 doses were reported as serious. The main challenge with any results from either agency is that reports are dependant on civilians reporting incidences. As a result, the numbers could be both under and over estimated due to people not recognizing/reporting or falsely recognizing adverse reactions.
The central anti-vaccine argument is even 1.6 serious adverse reactions out of 100,000 doses outweighs the actual risk of the diseases that vaccines are supposedly protecting against. Vaccines essentially protect against what could happen, whereas to a parent of an infant, vaccine-induced disease is a more valid possibility. The Public Health Agency of Canada contends that the risk of disease is in fact greater. They state that unless a disease has completely disappeared, there is always a risk that small outbreaks can become large epidemics if communities are not protected. Also, disease that may be rare in Canada can exist at much higher frequencies elsewhere in the world, and may be carried to Canada from other countries. Most of the diseases infants are vaccinated against can be fatal or cause serious complications; the possibility of infection cannot be taken lightly.
Several studies have been conducted on the resurgence of whooping cough in Europe (Celentano, et al., Baron, et al., Binkin, et al.) and North America (Bisgard, et al.) in relation to levels of immunization. Every study found unvaccinated or partially vaccinated young children were the most susceptible to infection and three studies found that unvaccinated children under one year were up to 70% more likely to be hospitalized. Based on this, one can stipulate that a real risk of resurgence of childhood disease could occur if vaccination strategies were relaxed.
On the other hand, VRAN presents graphs on their website that indicate the decline of these diseases before vaccination was introduced, compiled by Dr. Raymond Obosawin. The graphs represent a severe downward trend in death due to childhood disease in England and Wales dating to the early 1900s, long before vaccines were introduced (source of data was not given), inferring that vaccinations did not actually decrease disease incidence. Improved sanitation, food storage and health services are instead attributed to the decrease in death due to disease. These graphs can be misleading, as they only show data from one country, and only for a few diseases. On the other hand, international data available from the World Health Organization showed data no older than 1980, when vaccination strategies had been established for some time.
Regardless if vaccine contribution to disease was overstated in the past, it was shown in the whooping cough studies (other examples exist as well) that unvaccinated individuals now are considerably more susceptible to possibly acute disease; therefore vaccination does provide some degree of protection in present day.
A considerable issue in anti/pro vaccine debate is lack of clinical research. Anti-vaccine groups tend towards more unscientific and at times sensational representation of information, and the scientific community is almost too cavalier about the issue. Nearly every professor of microbiology I have taken courses with disregards any arguments of anti-vaccine groups, which is not surprising; even as an undergraduate I find the concept difficult to accept.
I do not believe that vaccinations are completely ineffectual and useless in the present world. If I was travelling to a third world country, I would update my immunizations; if there was a West Nile Virus vaccine I would want to be vaccinated; I think a nation-wide HPV vaccine campaign is an excellent idea. Whether or not the present strategy of infant immunization should continue is what I feel should be strongly debated and further researched. Members of anti-vaccine groups do not have anything to gain in questioning the efficiency of vaccines; in some situations they have already lost from not questioning it.
References
1. Canadian Guide to Immunization, 6th edition. 2002.
2. Janeway, Charles. Immunobiology, 5th edition. 2004.
3. Vaccine Risk Awareness Network. October 16, 2006. link
4. National Vaccine Information Center. October 16, 2006. link
5. West, Edda. Canaries in a Mine Shaft: The Crisis in Children’s Health. (2001) VRAN Newsletter, Fall.
6. Blaylock, Russell L., MD. Interaction of Cytokines, Excitotoxins, and Reactive Notrogen and Oxygen Species in Autism Spectrum Disorders. (2003) Journal of the American Nutraceutical Association, 6(4).
7. Afzal, MA, et al. Absence of detectable measles virus genome sequence in blood of autistic children who have had their MMR vaccination during the routine childhood immunization schedule of UK. (2006) Journal of Medical Virology, 78(5):623-30.
8. DeStefano, et al. Childhood vaccinations, vaccination timing, and risk of type 1 diabetes mellitus. (2001) Pediatrics, 108(6): E112.
9. Fleming, PJ, et al. The UK accelerated immunisation programme and sudden unexpected death in infancy: case-control study. (2001) BMJ, 7;322(7290):822.
10. Zhou, W, et al. Surveillance for safety after immunization: Vaccine Adverse Event Reporting System (VAERS)–United States, 1991-2001. (2003) MMWR Surveill Summ. 24:52(1): 1-24.
11. Public Health Agency of Canada. October 13, 2006. link
12. Celentano, LP, et al. Resurgence of pertussis in Europe. (2005) Pediatr Infect Dis J, 24(9):761-5.
13. Baron, S, et al. Epidemiology of pertussis in French hospitals in 1993 and 1994: thirty years after a routine use of vaccination. (1998) Pediatr Infect Dis J., 17(5):412-8.
14. Binkin, NJ, et al. Epidemiology of pertussis in a developed country with low vaccination coverage: the Italian experience. (1992) Pediatr Infect Dis J., 11(8):653-61.
15. Bisgard, KM, et al. Pertussis vaccine effectiveness among children 6 to 59 months of age in the United States, 1998-2001. (2005) Pediatrics,116(2):e285-94.
16. Disease decline before introduction of immunization. WHALE. October 16, 2006. link
17. Immunization, Vaccines and Biologicals. World Health Organization. link