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Defend Only the Defenseless
Genetic Variation and Vaccination

by Sergey N. Rumyantsev

(Posted May 14, 1999*·*Issue 54)
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Abstract

While infections leave many individuals untouched, our policy has been to
maintain a system of total vaccination. Growing knowledge about genetic
immunity could lead to a more precise delivery of prophylaxis to those who need
it.


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Human populations are very diverse in terms of susceptibility to infectious
diseases. This is clearly supported today by epidemiological, clinical, and
genetic observations and analyses. Every infection affects only part of the
species it attacks. Many individuals, families, and other population members
survive epidemics intact.

However, today's routine infectious disease prevention programs are based on
the principle of total vaccination. For instance, vaccines and chemoprophylaxis
to prevent secondary disease are recommended for all close contacts of patients
with meningococcal disease. When a case of meningococcal disease occurs, many
people may fulfill accepted criteria for receiving vaccine and
chemoprophylaxis. Meanwhile, the contacts of patients with meningococcal
disease have an increased but not absolute risk of contracting the infection.
According to Kristiansen et al. (1998) [1] only 2.7% of close contacts were at
risk for carrying the pathogenic strain of Neisseria meningitidis. Household
members' relative risk of contracting the disease was between 0.1 and 0.025%
(De Wals et al., 1984) [2]. Other members of the population were defended
without vaccination.

In unvaccinated individuals, resistance is provided mainly through
constitutional (genetic) immune factors. During the past two decades, there has
been an explosive growth in knowledge about the constitutional immunogenic
system.

Most people possess a natural resistance to infection. Therefore, prophylactic
measures are usually prescribed in excess of what is needed. This general use
of prophylaxis in all contacts today seems excessive. Vaccine and
chemoprophylaxis should be restricted to those who are genetically defenseless
and likely to be vulnerable to infection.

If such restrictions are effected, it is extremely important to be able to
identify susceptible individuals and populations, in order to determine in
advance which members do not possess genetic immunity and therefore require
vaccination and other prophylactic measures. Those who are naturally immune
should not be subject to these procedures, which are not always harmless, and
society should be spared the considerable expense of carrying them out on a
population-wide basis.

Sensitive and rapid tests to identify genetically susceptible individuals could
allow for the targeting of prophylaxis only to those in need; however, as of
now, laboratories lack the technology and resources to perform these tests. In
most cases, therefore, the decision of whether to give prophylaxis must be made
on the very dubious basis of the closeness of someone's contact with an
infected patient.

One of the aims of the Human Genome Project is to elucidate the genetic
determinants of disease resistance and susceptibility. Today, the successes of
immunology make it possible to develop the means to identify susceptible
individuals. This could be achieved without waiting for individuals to be
affected, by observing in vitro the interaction of infectious agents or their
molecular-ecological factors with the relevant cellular, subcellular, or
molecular structures, extracted from the individual in question.

It has been shown in many cases that primary cultured cells of constitutionally
sensitive organisms are affected by the infectious agents tested, whereas cells
of resistant organisms remain intact. This should be equally true of human
beings. It is time for us to reexamine our policies of maintaining "herd
immunity" when the Human Genome Project is moving so quickly to define us as
individuals.


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Sergey N.Rumyantsev is an immunologist studying the cellular and molecular
basis of genetic immunity at the Institute of Vaccines and Sera, Saint
Petersburg, Russia.

Andrzej Krauze is an illustrator, poster maker, cartoonist, and painter who
illustrates regularly for HMS Beagle, The Guardian, The Sunday Telegraph,
Bookseller, and New Statesman.


Endlinks

Communicable Disease Surveillance and Response - information from the World
Health Organization on monitoring, tracking, and preventing communicable
diseases. Includes global outbreak updates, reports on specific diseases, and
health advice for travelers.

Control and Prevention of Meningococcal Disease - recommendations from the
Centers for Disease Control Advisory Committee on Immunization Practices
regarding a polysaccharide vaccine and antimicrobial agents for
chemoprophylaxis against meningococcal disease.

Medicine and the New Genetics - this extensive section from the Human Genome
Project site reports on the impact that genetic research is having on medical
diagnosis and treatment. Among the section's many features are subsections on
Diagnosing and Predicting Disease and Disease Susceptibility and Disease
Intervention.

** NOTICE: In accordance with Title 17 U.S.C. Section 107, this material
is distributed without profit to those who have expressed a prior interest
in receiving the included information for research and educational
purposes. **