Page 1250 - Clinical Immunology_ Principles and Practice ( PDFDrive )

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Vaccines

Sarah Kabbani, Mark J. Mulligan

It might be fair to imagine that the field of vaccinology began That vaccines have a societal benefit in addition to the
with the first recognition that a person who survived an infection individual protection provided to the vaccine recipient is a special
was much less likely to suffer from that disease in the future in and gratifying aspect of this highly valuable biomedical interven-
comparison with a person who had not previously had the disease. tion. Vulnerable community members whose immune systems
That is, the infectious disease, if it did not kill the person, resulted are unable to respond well to vaccines (newborns, immuno-
in an experienced, protected state. Today we would say that the compromised persons, older adults) or are unable to receive
protected survivor had immunity. vaccines (because of allergy or a medical contraindication) depend
Vaccines are clinically simple but immunologically complex on immunization of surrounding community members for
preventive or therapeutic interventions that can dramatically protection against vaccine preventable diseases. The vaccinated
reduce morbidity and mortality caused by infectious diseases in community becomes an immunological cocoon or wall of protec-
children, adolescents, adults, and seniors. In recent years, vac- tion for these vulnerable members of society.
cinations against other categories of disease have become an This chapter first reviews selected events in the history of
increasingly active area of research (e.g., cancer and dementia). vaccination, both distant and recent. The remarkable accomplish-
In addition, vaccines against microbes are increasingly appreciated ments that have resulted from programs of vaccination to
for their potential role in the medical field’s heightening battle date are then highlighted. We also describe important recent
against antimicrobial-resistant bacteria. For example, the protein milestones and changes in vaccine development strategies
conjugate pneumococcal vaccine was shown to reduce the that have the potential to revolutionize the field and offer great
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incidence of antibiotic-resistant pneumonia. Preventing an illness hope for providing solutions for unmet vaccine needs. Current
through vaccination obviates the need to treat a bacterial infection vaccine recommendations are then summarized. Finally several
with antibiotics, thereby avoiding potential induction of antibiotic present and future challenges for the field of vaccinology are
resistance in either the targeted pathogenic bacterium or the discussed.
patients’ healthy microbiota.
Another important area of recent emphasis has been the HISTORY OF VACCINES
double power of vaccinations for pregnant women, protecting
two—mother and infant—against the targeted pathogen (e.g., The earliest known vaccines for which records have been identified
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3,4
pertussis or influenza ). In addition, a critical need for pre- were against smallpox and were used in Asia early in the second
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pregnancy vaccination to protect pregnant women and their millennium. Of course, they were not called “vaccines.” The
fetuses ahead of and during the highly vulnerable first trimester practice was called variolation and involved exposing, usually
of pregnancy is currently underscored by acquisition of Zika through the intranasal route, a smallpox-susceptible (not previ-
virus infections during pregnancy with resulting microcephaly ously infected) person to material from the dried scabs of a
and other birth and developmental anomalies. 5-8 person who had had smallpox. If the recipient survived, he or
Although senior citizens (>65 years of age) experience high she was protected against future smallpox disease. Since natural
proportions of the total morbidity and mortality for several vaccine smallpox had a 30% mortality rate and variolation had a lower
preventable diseases (e.g., seasonal influenza, pneumococcal disease, (≈1%) mortality rate, this ancient practice was an early example
herpes zoster) as a result of immunosenescence, they are least of weighing the risk-to-benefit ratio for a human health interven-
able to mount their own protective immune responses after tion. By 1700, variolation was employed in a number of societies
vaccination. Community protection (also termed herd immunity) in Africa, India, and the Ottoman empire, and it was in use in
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of seniors by vaccination of children, who are the primary spreaders England and France in the 1700s. The practice of variolation
of many vaccine-preventable infectious diseases, and younger was not without risk and sometimes caused outbreaks of a mild
adults can provide dramatic reductions in infectious disease form of the disease. One of the many who died as a result of
incidence in seniors—for example, the reduction in pneumococcal variolation was a son of England’s King George III.
disease in seniors after the introduction of pneumococcal conjugate In 1796, an English physician was searching for a safer alterna-
vaccine for children. 9,10 Despite suboptimal vaccine responses tive to variolation. This physician was to become known as the
with aging, several vaccines are specifically recommended for father of vaccinology—Edward Jenner. He performed a smallpox
seniors (see Fig. 90.3) and some of the vaccines for seniors now vaccination experiment on James Phipps on May 14, 1796, using
employ novel strategies to enhance the immunosenescent response, as vaccine cowpox pus from the lesions on the hands of Sarah
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such as high doses of influenza antigen 11,12 or coformulation of Nelmes, a milkmaid. Dr. Jenner then collected lesion material
virus antigen with an adjuvant. 13,14 from a patient with smallpox and used this as the viral challenge
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