‘Everyone else’s child is protected so mine does not need to be immunized’

January 2002

---Philip A. Brunell, MD

Everyone else’s child is protected so mine does not need to be immunized.” Does this sound familiar? It is a mindset that is common and often heard from well-meaning and otherwise well-informed parents. It is interesting how many parents have “taken control” of their medical care and seem to be still searching for the answers on how to raise their children.

They are correct when they point out that the diseases which are used to kill and injure our children have largely disappeared due to our successful efforts at immunization and that (almost) “everyone else’s child is protected.” Our immunization rates continue to increase. For example, meningitis caused by Haemophilus influenzae type b has virtually disappeared, and there were fewer than 100 cases of measles in the last reporting period. Most recent medical graduates will never see this disease or mumps or rubella.

On the surface it appears as one need not be concerned about preventable disease. Although immunization rates exceed 90% by any measure, we have had pockets of unimmunized populations, which in the past, have provided enough susceptibles to fuel epidemics. During these epidemics, we have seen infections of those who appeared to be protected by “everyone else.” Unprotected adults, who generally are much more likely to suffer severe illnesses when they contract childhood disease, often are among the most affected. Finally, our vaccines are not perfect. As the number of unimmunized and the vaccine failures accumulate, we have experienced epidemics. Although we may revel in our success now, we may ask, what happens a few years from now.

Perceived risk

Certain parents have misjudged risk. When they are reluctant to have their children immunized, it is in the belief that the risk of vaccines is greater than the risk of the disease they are intended to prevent. However, health officials also have been guilty of miscalculating the risk of disease. Soon after the licensure of measles vaccine, there was a precipitous drop in cases. Impressive enough to have a goal set for the elimination of measles. Only a few years later, we were to experience another epidemic of measles. This was to occur two more times, most recently about a decade ago. Our current success in measles elimination has resulted from the recognition that the vaccine was imperfect and that a second dose was required. But as we look back on that epidemic, there are other lessons to be learned. Although the statistics for the country as a whole looked very good, the immunization rates for preschoolers in some inner cities were dismal. The rate of measles in those cities as a whole was inversely related to the immunization rates of these children in their inner cities.

Those who rejected immunization on religious grounds were another pocket of susceptibles. In a Midwestern college sponsored by such a group, there was a severe epidemic with some deaths in college students. Although these individuals were safe in times between epidemic periods, they were obviously very vulnerable during epidemics. Now protection of college students is strongly recommended.

What often is forgotten is that the risk of childhood diseases does not stop when one grows into adulthood.

Going to college, taking a job or going into the armed services brings adults into contact with a new group. Thus it is not uncommon to find epidemics of childhood diseases, eg, measles, meningococcus, rubella or influenza in these situations. In addition, foreign travel carries with it the risk of exposure to many diseases against which most Americans are protected.

One of the major concerns with varicella vaccine (Varivax, Merck) is the possibility that it might be postponed from a childhood to an adult disease as immunization rates increase. Although only about 2% of the reported cases occur in individuals older than 20, one-half of the deaths occur in adults. What we now are witnessing is a decrease in cases in those younger than 1 year, suggesting that there is some herd immunity occurring. Thus the chance of those who are unimmunized growing into adults without having gotten chickenpox is increased. In analyzing what would happen to adult disease after introduction of the vaccine, it was projected that a 70% rate of immunization would later lead to increased adult disease and periodic epidemics in children. We are now at 70%. Parents who deny their children chickenpox vaccine are foolhardy.

Vaccine-preventable diseases

Periodic epidemics of illness have been well recognized. Before the vaccine, we used to have “bad” measles years alternating with not so bad years. After the introduction of vaccine, the interval between epidemics increased as the number of susceptibles needed to sustain an epidemic was diminished. Each disease appears to have its own cycle.

In the case of pertussis, we still have epidemics estimated to occur every 3.2 years. This despite the fact that >90% of U.S. children are immunized with pertussis-containing vaccines. It is of interest that in 1999, there were more than 6,000 cases of pertussis reported, while there was only 33 cases of tetanus and a single case of diphtheria. Yet, they all are contained in the same vaccine. Except, of course, the adults that receive dT — but this is a small fraction of the vaccine administered. One could assume that the pertussis components are not as effective as the others. In addition, the protection offered by pertussis vaccine is incomplete. Some of the vaccinees can be infected with Bordetella pertussis and transmit disease without themselves having recognizable pertussis. When enough susceptibles accumulate they can be infected by these people and this may result in periodic epidemics. The absence of pertussis does not equate to the absence of risk. Pertussis may be delayed beyond infancy, when almost all deaths occur, but it may occur at a most inconvenient time.

Appreciating risk

Appreciating the risk of vaccines also may be difficult. During the first 6 months of life, when most of the sudden infant deaths and about one-half of the cases of infantile spasms will occur, we give about 4 million children more than a dozen vaccines. Some of these children, by chance, will suffer one of these conditions or another devastating event after immunization. It is understandable that parents may believe that these temporally related events also are causally related, despite the many carefully done studies which disprove that these temporally associated events are not causally related. Distinguishing between the two requires a fair amount of sophistication, which it is unreasonable to expect untrained people to have.

Finally, it is interesting to read the following:

“The advocates of vaccination have exalted in the prospect of exterminating the smallpox from the face of the earth; while its opponents have framed their tales of horror, replete with stories of novel diseases and unheard of plagues … When I consider the many evidences in favour of vaccination, which the public documents of almost every nation afford, I am at a loss to conceive from what course such doubts can have arisen/for I think. If an unprejudiced mind will fairly consider the question, it must be convince that vaccination has answered the promised end.”

Published in The Gentleman’s Magazine, March 1808 by “Cosmopolitan” (Archives of Dis Child. 2001;85:271).