Those of us born before 1971 may have a distinctive scar on our arms or legs: the coin-sized result of a smallpox vaccination. Today’s children no longer need this immunization, smallpox having been eradicated from the face of the earth by 1977. Polio is also nearing eradication; the last documented case of wild poliovirus in the United States occurred in 1979. Since then, reported cases have been either vaccine-associated or imported. By 1991, polio caused by wild-type viruses had been eliminated from the Western Hemisphere. Most physicians educated since 1985 have never seen a case of measles. In fact, in 1998 measles reached a record low number of 89 cases with no measles-associated deaths; all of these cases were imported from outside the United States. Such is the power of the child immunization program.

With this level of success, why continue vaccinating children, especially since there are risks involved? Simply put, stopping vaccination short of eradication would expose children to an unacceptably high risk of serious epidemics. Except for smallpox, all the other childhood diseases still exist in other parts of the world. In an increasingly peripatetic society, these organisms could easily be imported into the United States. Discontinuation of the immunization process would result over time in a group of vulnerable individuals. The result would be a return to the previous levels of disease. In addition, there are no cases where the risk of the vaccine outweighs the risk of actual disease (this, in fact, is one of the criteria the FDA imposes before licensing a vaccine). Finally, there is the concept of “herd immunity.” There are a small number of individuals who cannot be immunized (allergic reactions to vaccines, for instance). Since they are vulnerable, elimination of the disease in those around them would protect them from transmission.

The following figure is the latest recommendation for childhood immunizations, taken from the CDC Web site. This is followed by a brief discussion of the diseases themselves.

Vaccines are listed under routinely recommended ages. Bars indicate range of recommended ages for immunization. Any dose not given at the recommended age should be given as a "catch-up." Immunization at any subsequent visit when indicated and feasible. Ovals indicate vaccines to be given if previously recommended doses were missed or given earlier than the recommended minimum age.

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Approved by the Advisory Committee on Immunization Practices (ACIP), the American Academy of Pediatrics (AAP), and the American Academy of Family Physicians (AAFP).

• Hepatitis B is a viral disease which primarily attacks the liver. Unfortunately, disease which is acquired in infancy carries a much higher risk of complications, such as chronic hepatitis, cirrhosis or hepatic failure. Cirrhosis and hepatic failure are almost always eventually fatal unless liver transplantation occurs.

1. Diphtheria begins with a fever and sore throat, but is characterized by a pseudomembrane which develops at the back of the throat. This pseudomembrane causes difficulty breathing and can completely obstruct the throat. Cardiac and neurologic complications can also occur. In children under 5 years of age, there is a 20 percent mortality rate. At its peak (in 1921) 206,939 cases occurred; in 1997, there were five cases.

2. Tetanus is also known as “lockjaw.” It is caused by a bacterium that lives mainly in the soil. The disease causes uncontrollable spasm of the muscles, and is fatal more than 80 percent of the time. At its peak (in 1948), 1,560 cases were estimated to have occurred (there was no reporting requirement at the time); in 1997, there were 43 cases.
3. Pertussis is also known as whooping cough because of its distinctive sound during paroxysms of coughing. Nearly all children developed pertussis before immunization was widely available. Each year, about one in 2,000 died from the disease. Pertussis can be severe, causing prolonged coughing and vomiting spells that can last for weeks. These spells make it difficult for a child to eat, drink and breathe. In infants, it can also cause pneumonia and lead to brain damage, seizures and mental retardation. At its peak (in 1934), 2,655,269 cases occurred; in 1997, there were 5,519 cases.

Td (Tetanus booster): used only after the initial immunization schedule, or if a child is allergic to pertussis.
Hib (Haemophilus influenza type b)

• Haemophilus influenza type b is a bacterial disease which can cause meningitis in infants and epiglottitis in older children. While many infections are not as serious, up to 600 children died per year prior to widespread immunization. Those who survived severe invasive disease were often left with seizures, mental retardation and hearing impairment. At its peak (in 1984), 20,000 cases were estimated to have occurred (there was no reporting requirement at the time); in 1997, there were 1,056 cases.

IPV (Injectable Polio Virus)

• Poliomyelitis is caused by poliovirus. It results in acute paralysis that can lead to permanent physical disability and even death. Before polio vaccine was available, annual epidemics of polio often left thousands of victims (mostly children) in braces, crutches, wheelchairs and iron lungs. At its peak (in 1952), 21,269 cases occurred; in 1997, there were no cases from wild virus.

MMR (Measles, Mumps, Rubella)

• Measles was once considered a usual childhood disease, much like chickenpox. An average of 450 measles-associated deaths were reported each year between 1953 and 1963. Complications include pneumonia; diarrhea; ear infections; or encephalitis, which often results in brain damage. As many as one of every 1,000 persons with measles will die. At its peak (in 1941), 894,134 cases occurred; in 1997, there were 135 cases.
• Mumps is a viral infection of the parotid glands which is generally benign. It can result in pancreatitis, orchiitis (an inflammation of the testicles in post-pubertal males which can cause sterility), or viral meningitis which does not result in permanent damage. At its peak (in 1968), 152,209 cases occurred; in 1997, there were 612 cases.
• Rubella is usually mild in children and adults. Unfortunately, infection during the first trimester of pregnancy causes congenital rubella syndrome in up to 90 percent of infants. Congenital rubella syndrome results in heart defects, cataracts, mental retardation and hearing impairment. At its peak (in 1969), 57,686 cases occurred; in 1997, there were 161 cases.

Var (Varicella)

• Varicella is commonly called chicken pox. It is caused by a virus of the herpes family (adults who have had chickenpox can have a recurrence known as “shingles”). While it is normally a benign disease, it can cause pneumonia and encephalitis. It has also been implicated in Reye’s Syndrome, a severe and devastating encephalitis.

Hep A (Hepatitis A)

• Hepatitis A is a viral disease which primarily attacks the liver. Unlike hepatitis B, hepatitis A does not cause chronic hepatitis or cirrhosis. It can, however, cause hepatic failure, which could be fatal.