“Study Shows Autism Is Linked to the MMR Vaccine,” the newspaper’s headline reads. A television news magazine runs a story filled with testimonies from parents about the deaths of their children just days or weeks after they received the DPT vaccine. Coalitions of parents form to call for the banning of current vaccines until better and safer ones are discovered. Meanwhile, medical professionals and politicians call for increased coverage rates with vaccines and encourage parents to continue immunizing their children.
Many parents, their heads spinning from listening to all of this, compromise and adopt an attitude like this one: “If everyone else is immunizing, then the immunity of others will keep my child safe and I won’t have to worry about the potential side effects from vaccines.” Often those who practice this are unaware of the consequences of their decision for both their own children and society at large.
Robert Chen and Frank DeStefano point out that criticism of vaccines becomes more common when the risk of the contracting the disease is low. This happens because, at that point, coverage of the vaccine is high and reports of side effects (whether genuinely associated with the vaccine or simply coincidental events) are bound to be more common1.
A potent example of this occurred in the early 1970s. Pertussis, more commonly known as whooping cough, was at record lows in developing countries with the use of the whole-celled pertussis vaccines. Studies appeared that seemed to link the vaccine to serious side effects in rare cases, and in extremely rare situations, death. Some countries continued their immunization programs with very little interruption in coverage while others, listening to the voices of worried parents and health professionals alike, terminated or modified immunization for pertussis for several years. E.J. Gangarosa and his colleagues researched the medical literature, popular literature, and disease case rates of several countries during this period and into recent years to chart the effects of this interruption, and their work has much to say about the costs associated with listening to the anti-vaccination movement.
Sweden’s immunization program against pertussis began in the 1950s. Disease case rates were at their lowest in the years leading up to the termination of the program in 1979, though several voices began to question the necessity and safety of the program early on, among them Justus Storm. A leading member of the Swedish medical community, he claimed that medical technology had advanced so much that pertussis was less dangerous than it once was and national vaccination programs could be terminated. When case rates for pertussis saw a minor increase, doctors began to question the efficacy of the vaccine as well. Later, some neurological problems were attributed to the vaccine, and pertussis immunization came to a screeching halt2. For the next three years, pertussis levels were still low, but then the climb in case rates began, and there were serious outbreaks in 1983 and 1985. Annual case rates for the general populace rose from about 75 per 100,000 people to 100-200 per 100,000 people (about a 2-fold increase). It is estimated that the annual number of cases per 100,000 children (age 0-6) rose from 700 in 1981 to 3200 (a 4.6-fold increase) in 19853. So we see that the children were hardest hit by the fact that the vaccination rate fell.
One particularly striking way of seeing the effect of Sweden’s drop in the pertussis vaccination rate is to compare pertussis in Sweden to pertussis in Norway. While Sweden was persuaded by the anti-vaccination movement; Norway was not. Norway continued its pertussis vaccination program, and as a result, its population remained protected. Compare the pertussis rates in the two countries as shown in the graph below4:
Since Norway and Sweden are neighboring countries at roughly the same socioeconomic level, one would not expect any significant difference in their level of health care, sanitation, etc. This is why the pertussis rates in the two countries were roughly equivalent from 1974-1982. Notice, however, that starting in 1983, the number of pertussis cases in Sweden began to rise dramatically, while the number of pertussis cases in Norway continued to decrease.
This graph dramatically illustrates the problem with listening to the anti-vaccination advocates. Due to the drop in the pertussis vaccination rate in Sweden, thousands of innocent children in Sweden needlessly suffered (and sometimes died) from the ravages of pertussis. Unfortunately, this sad tale has been repeated in several countries. Spain, Greece, the UK, Japan, and Canada also experienced drops in the pertussis vaccination rate. Directly following that, they experienced pertussis case rate increases of 10 to 100 times compared to their neighboring countries who did not listen to the anti-vaccination advocates 5.
The key concept behind the need for high vaccine coverage is that of herd immunity. That is, if everyone is immunized, the transmission of the disease can be slowed or stopped. This is important for three reasons. The first is that no vaccine is 100% effective for all people. As a result, there will always be a small percentage of people for whom vaccination does not work because their immune systems do not respond to vaccination, and thus they will always be at risk for those diseases.
The second reason, an increasing problem in the face of HIV and similar disorders, stems from the vaccination of those suffering from immune deficiency disorders. Their immune systems are too weak to handle vaccination, and therefore they should never be vaccinated. For those who cannot be immunized for such reasons, it is imperative that those around them be vaccinated so that the organism that causes the disease will no longer be transmitted to them. This is the only way that they can be safe from the risk of disease.
The last reason is for the sake of infants who are too young to be immunized. In a study done of infants hospitalized for pertussis, most of them contracted it from family members. “The clear message is that, if herd immunity is lost,” Nick Pigott and his colleagues say, “the most vulnerable children (preimmunisation infants) are at greatest risk. The consequences are potentially devastating.”6 In light of the importance of herd immunity, the attitude mentioned earlier (refusing to vaccinate a child assuming that your children will be protected by others’ vaccination) is shown to be dangerous. Indeed, the immunity of everyone around a child does help protect the child to an extent, but that child is also at risk to a much greater extent than his immunized neighbors. More importantly, as more people follow this practice, fewer people surrounding him are immunized.
In country after country, in many varying circumstances, the result is the same – a lack of vaccination coverage is a recipe for epidemic. When a parent does not vaccinate his or her child, not only is that child’s health at risk, but the health of everyone around that child is also at risk.
1. Robert Chen and Frank DeStefano, “Vaccine Adverse Events: Causal or Coincidental?” The Lancet. 1998;351:612 ( Available online)
2. EJ Gangarosa, et al. “Impact of Anti-Vaccine Movements on Pertussis Control: the Untold Story.” The Lancet.1998;351:357 ( Available online)
3. V Romanus, R Jonsell, and SO Bergquist. “Pertussis in Sweden After the Cessation of General Immunization in 1979.” Pediatric Infectious Disease Journal. April, 1987; pp.364-71
4. Gangarosa et al. Ibid, p.360
5. Ibid, p.360
6. Nick Pigott, et al. “The Importance of Herd Immunity Against Infection.” The Lancet. 2002;360:645.( Available online)
*Erica A. Sommerville is not a medical doctor but a college student. She does not dispense medical advice. Her aim is to educate the public about scientific issues. Please consult a board-certified medical doctor before making any medical decisions for yourself
or your family.