Journal Issue: Children and Divorce Volume 4 Number 1 Spring/Summer 1994
Vaccination is the most important medical intervention to prevent disease. Not only are immunized individuals themselves protected from developing a potentially serious illness, but also, if enough of the population is immunized, transmission of the disease in a community may be interrupted.1 This indirect, so-called herd immunity, provides protection even to those who are not themselves immunized. Vaccines have been developed, and more are currently being developed, to protect children and adults from a number of potentially serious diseases. Failure to achieve adequate and timely rates of immunization among young children with available vaccines risks outbreaks of serious diseases with a resulting increase in unnecessary death and disability. Because certain vaccine-preventable diseases (especially measles, pertussis, and Haemophilus influenzae type b infection) can have devastating effects on young children, this Child Indicators article focuses on the immunization status of children 19 to 35 months old (classified as two-year-olds for reporting purposes).
In essence, a vaccine provides a controlled exposure to a disease as a way of priming the body's natural defense against infection. Traditionally, vaccines have consisted of components of disease-causing organisms which have been treated to reduce their virulence.
Frequently, multiple doses of a vaccine are necessary to gradually build up the body's defenses against future infection while minimizing the possibility of adverse effects from the vaccine itself. Also, as immunity may wane with the passage of time, so-called booster doses of the vaccine may be necessary to sustain protection.
To date, vaccines have been developed to protect young children from a number of infectious diseases including, but not limited to, diphtheria, tetanus, and pertussis or whooping cough (DTP vaccine); measles, mumps, and rubella or German measles (MMR vaccine); polio (OPV); hepatitis B (HBV vaccine); and Haemophilus influenzae type b (Hib vaccine).2 Recommendations for use of a vaccine depend on balancing the benefits and risks of vaccination with the risks of disease. Recommendations must be reassessed periodically. For example, children are no longer vaccinated against smallpox because smallpox was eradicated by the late 1970s.3