Immunizations - Introduction

Introduction

Immunizations against childhood diseases save millions of lives. American vaccination rates are now at an all-time high. Illness and death from diphtheria, pertussis (whooping cough), tetanus, measles, mumps, rubella (German measles), and Haemophilus influenzae (H. influenzae) type b are at or near record lows. In adults, immunizations against influenza (the flu), pneumococcal pneumonia, hepatitis, and other ailments have likewise saved many lives and prevented many cases of serious illness. A new vaccine has been shown to be highly effective against some strains of a virus that leads to cervical cancer.

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More than 70 bacteria, viruses, parasites, and other infectious microbes cause major human disease. Fortunately, vaccines are either available or being developed against a portion of them. With the advent of new or newly feared biological threats, emerging infections, and bacterial resistance to common antibiotics, immunizations are assuming an increasingly important role in maintaining the health of billions of people worldwide.

Immunization exposes you to a very small, very safe amount of the most important infections. This exposure helps your immune system recognize and attack the infection and prevent the disease it may cause. If you are exposed to the full-blown disease later in life, you will either not become infected or have a much milder infection.

Vaccine Forms

Most vaccines are given by an injection, but some can be taken orally (by mouth) or by a nasal spray. They usually contain one of four components that cause an immune response:

A live but weakened virus. Live-virus vaccines provide longer immunity than inactivated ones, but they can cause serious infection in people with weakened immune systems, and have also been associated with severe medical disorders in rare instances.
Inactivated bacteria, viruses, or toxoids. Inactivated vaccines are safe even in people with impaired immune systems.
A toxoid, is an altered form of a harmful substance (toxin) released by certain bacteria. The toxoid in vaccines is changed so it does not harm the person, but still produces an immune response.
Bacterial or viral components are not the whole organism, but only parts of the microbe that trigger a strong immune response.