Common Vaccinations
Children typically receive a number of vaccines according to a standard schedule (see Section 23, Chapter 263). Depending on their circumstances, adults may also be advised to receive certain vaccines. Factors that a doctor considers when advising adults about vaccination include the person's age, health history, childhood vaccinations, occupation, geographic location, and travel plans.
Measles, Mumps, and Rubella
Measles, mumps, and rubella (German measles) are all viral infections. Anyone born after 1956 who has never had one of these infections and who has not received two doses of the vaccine--but who is likely to be exposed to these diseases--should be vaccinated. People likely to be exposed to these diseases include those beginning college, joining the military, or working in schools or child care centers. Pregnant women and people who are allergic to eggs or the antibiotic neomycin should not be vaccinated.
A person can receive individual vaccines for measles, mumps, or rubella. However, a combination vaccine that helps protect against all three of these diseases is more often administered. This vaccine is recommended because anyone who needs protection against one of these infections usually also needs protection against the other two.
Tetanus
Tetanus vaccination protects the body against the toxin produced by the tetanus bacterium, not the bacterium itself. Because tetanus is often fatal, vaccination is particularly important. A primary series of three injections over a 6-month period should be administered to any adult who was not vaccinated in childhood. A booster dose of the vaccine is recommended every 10 years. Adults receive the tetanus vaccine alone or in combination with a diphtheria vaccine administered in a single injection. Children receive a combination vaccine against tetanus, diphtheria, and pertussis (whooping cough). Pertussis vaccination is not necessary for adults.
Hepatitis A
Vaccination against the hepatitis A virus is recommended for adults and children older than age 2 traveling outside of the United States (except to Canada, Northern/Western Europe, Australia, New Zealand, and Japan) and for injecting drug users, male homosexuals, and people with chronic liver disease or blood clotting disorders. Two doses, 6 to 12 months apart, are given. In communities with high rates of hepatitis A, children should routinely be given the vaccine.
Hepatitis B
Hepatitis B vaccination is recommended for all children and for any adult who is at high risk of exposure to the hepatitis B virus. People at high risk include health care workers, mortuary workers, people receiving frequent blood transfusions or dialysis, injecting drug users, people who have multiple sex partners, and sex partners and household contacts of people known to be carriers of hepatitis B.
The vaccine is given in a series of three or four injections. However, if a person who has been vaccinated is exposed to the virus, a doctor measures that person's antibody levels against hepatitis B. If the antibody levels are low, the person may need another injection of hepatitis B vaccine. People with a history of severe allergic reaction to baker's yeast, which is used in the production of the vaccine, should not receive the vaccine.
Haemophilus influenzae type b
All children should be vaccinated against the bacterium Haemophilus influenzae type b. Protection is not required by adults, in whom the infection is very uncommon.
Influenza
Vaccination against the influenza virus is recommended for people at high risk of developing influenza or its complications. People at risk include residents of nursing homes, those older than 50, and health care workers. Others at risk include people with chronic heart or lung disease, diabetes, kidney failure, sickle cell disease, a weakened immune system, or human immunodeficiency virus (HIV) infection.
Influenza epidemics usually begin in late December or midwinter. Therefore, the best time to receive the vaccine is in September or October. Influenza vaccination must be repeated every year because the virus changes from year to year.
Pneumococcal Infection
Vaccination against pneumococcal infection is recommended for all children; a newly developed vaccine for children is highly effective. Adults who are at high risk of developing pneumonia should receive the adult vaccine. People at high risk of pneumonia include those with chronic disease (especially lung and heart disease), those who do not have a functioning spleen, those with cancer of the blood cells, those with spinal fluid leakage, and alcoholics.
The adult vaccine is effective in about two of three adults, although it is less effective in debilitated older people. It is more effective in preventing some of the serious complications of pneumococcal pneumonia than in preventing the pneumonia itself. Although one injection of the vaccine may provide lifetime protection, people at high risk are advised to receive the vaccine every 6 years.
Polio
All children should be vaccinated against polio. Until recently, the vaccine most often used contained live, weakened virus and was given by mouth. However, about 1 in every 2.4 million people who receives this oral polio vaccine develops a case of polio (the chance of getting polio from the oral vaccine is higher in people with a weakened immune system). Because of this, doctors in the United States now use an injectable polio vaccine that contains killed virus that cannot cause the disease.
Because polio is now so rare in the United States, unvaccinated people older than 18 do not receive the polio vaccine unless they are traveling to an area where polio is common.
Varicella
Vaccination against varicella (the virus that causes chickenpox) is part of the routine vaccination schedule recommended for children. The vaccine is relatively new, however, so older children and adults who have never had chickenpox may want to consider vaccination, especially because the infection tends to be more serious when acquired in adulthood. The vaccine does not completely prevent chickenpox, but vaccinated people who do get the disease usually have milder symptoms. It is likely that the varicella vaccine helps prevent shingles (see Section 17, Chapter 198), a complication of chickenpox that can produce painful skin sores years later.
The vaccine is administered in two doses 4 to 8 weeks apart. The vaccine is not given to pregnant women, people with a weakened immune system, or people with cancer affecting the bone marrow or lymphatic system.
Smallpox
Vaccination against smallpox was once routine for everyone in the United States. Smallpox vaccination was discontinued over 20 years ago because of the elimination of the disease. Because the vaccine's protective effects wear off after about 10 years, most people are now susceptible to smallpox. Recent fears about the possible use of smallpox by terrorists have led to the suggestion that smallpox vaccination resume. The vaccine is generally safe, although serious adverse reactions develop in about 100 of every million previously unvaccinated people, and death occurs in 1 per million. The risk of serious adverse effects and death is lower in previously vaccinated people. If smallpox vaccination is resumed, it is likely to be recommended only for people in the area of a smallpox outbreak. The vaccine is most effective when given very early after exposure, but may also benefit people who have contracted smallpox if given in the first days after symptoms appear.
 See the table Protecting Against Disease.
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