Immunization

September 14, 2011

Adult immunization has not received the emphasis that has been directed toward vaccinating infants, children, and adolescents. Although vaccination is routine in pediatric practice, it is not commonplace in the practice of physicians who treat adults. Vaccines that should be considered in adult women include tetanus, influenza, MMR (measles, mumps, rubella), varicella-zoster, pneumococcus, meningiococcus, and hepatitis A and B. Indications for the specific vaccines and unique issues of vaccination in pregnancy are discussed below.

Adults should receive a booster dose of tetanus every 10 years. A primary series for unvaccinated adults is three doses: the first two doses given at least 4 weeks apart and the third dose, 6-12 months after the second.

Infection with the influenza virus produces more morbidity and mortality than any other infectious agent. Each year new strains of influenza circulate in the community, and protection requires annual vaccination. Influenza vaccination has long been strongly recommended for individuals over the age of 65 and those with chronic medical conditions. In recent years there has been increasing emphasis on vaccinating healthy adults less than 65 years of age. Recent studies have shown that vaccinating healthy working adults prevents illness and is cost effective. The traditional influenza vaccine is given by injection. The Food and Drug Administration (FDA) recently approved an influenza vaccine that can be administered by a nasal spray.

In the past few years, hepatitis B vaccination has become universal for all children, and is recommended for sexually active young adults. Childhood immunization with hepatitis B is relatively recent, and teenagers and young adults may not have been vaccinated. Hepatitis B vaccination is also recommended for health care workers, patients with chronic renal failure, and individuals whose job or lifestyle put them at increased risk for exposure to blood and body fluids. Hepatitis B vaccination requires three injections, the second and third given 1 and 6 months after the initial shot. Hepatitis A vaccine is most commonly given to travelers who will visit developing countries. Hepatitis A is by far the most common vaccine-preventable disease in travelers. A single dose of the vaccine provides full protection but only lasts 2-3 years. A booster given 6-18 months after the initial dose provides long-lasting protection. In addition to travelers, individuals with occupations known to be high risk for hepatitis A, such as intravenous drug users and, should receive the vaccine.

Vaccination against the bacteria Streptococcus pneumoniae with the pneumococcal polysaccharide vaccination is recommended for patients over 65 and those with specific chronic medical conditions such as renal failure, immunosuppression, liver disease, and cancer. Clinical trials have demonstrated that the pneumococcal vaccine is effective in preventing complications of S. pneumoniae such as sepsis, death, and meningitis in healthy elderly individuals. The benefit of preventing pneumonia is less clear. Patients who have had their spleen removed have an increased risk for sepsis due to S. pneumoniae and should receive the vaccine. The current recommendation is for a one-time vaccine with a booster after 5 years for patients over the age of 65, and every 5 years for the high-risk nonelderly.

Young adults are the most common age group that needs MMR vaccination. Measles and rubella are primary concerns in women. Adults born before 1957 may be considered immune to measles based on natural infection, which was almost universal prior to the introduction of the measles vaccine. A booster immunization with the live MMR vaccine after the first year and a half of life provides lifelong protection against measles. Routine use of the live vaccine began in the past decade and a half; and adults born after 1957 and before 1990 may not have received vaccination that will have long term protection. Adults born in or after 1957 should receive at least one dose of MMR unless they have a medical contraindication, documentation of at least one dose, or other acceptable evidence of immunity. A second dose of MMR is especially recommended for adults recently exposed to measles or in an outbreak setting, those who were vaccinated with an unknown vaccine between 1963 and 1967, are students in postsecondary educational institutions, work in health care facilities, or plan to travel internationally. One dose of MMR should be given to a woman whose rubella vaccination history is unreliable. Women should be counseled to avoid becoming pregnant for 4 weeks after vaccination. Women of childbearing age, regardless of birth year should have determination of rubella immunity. One lifetime dose of MMR should be adequate for protection against mumps.

Vaccination against the varicella-zoster virus (VZV), the causative agent of chickenpox, is recommended for all persons who do not have a reliable clinical history of varicella infection, or serological evidence of VZV infection, and have specific risks. Those at increased risk for VZV include health care workers and family contacts of immunocompromised persons, those who live or work in environments where transmission is likely (e.g., teachers of young children, day-care employees, and residents and staff members in institutional settings), persons who live or work in environments where VZV transmission can occur (e.g., college students, inmates, and staff members of correctional institutions, and military personnel), adolescents and adults living in households with children, women who are not pregnant but who may become pregnant in the future, and international travelers who are not immune to infection. Greater than 90% of U.S.-born adults are immune to VZV. Pregnant women or those planning to become pregnant in the next 4 weeks should not be vaccinated. Childhood vaccination against VZV is becoming routine; the duration of protection and the need for revaccination remain unknown.

The meningococcal vaccine protects against sepsis and meningitis due to the bacterium Neisseria meningitides. Young adults, particularly college students living in dormitories, are at increased risk for contracting N. meningitides, and should be considered for vaccination. It is becoming routine to offer meningococcal vaccination to students entering college. Others at increased risk include adults with terminal complement component deficiencies, with anatomic or functional asplenia (lack of a spleen). Travelers to countries in which disease is hyperendemic or epidemic (“meningitis belt” of sub-Saharan Africa, Mecca, Saudi Arabia for Hajj) should also be vaccinated. Vaccination requires one shot, but the duration of protection is only 4 years, and revaccination is required for continued protection.

Generally, live-virus vaccines are contraindicated for pregnant women because of the theoretical risk of transmission of the vaccine virus to the fetus. If a live-virus vaccine is inadvertently given to a pregnant woman, or if a woman becomes pregnant within 4 weeks after vaccination, she should be counseled about the potential effects on the fetus. However, livevirus vaccination during pregnancy is not ordinarily an indication to terminate the pregnancy.

Whether live or inactivated vaccines are used, vaccination of pregnant women should be considered on the basis of risks versus benefits, that is, the risk of the vaccination versus the benefits of protection in a particular circumstance. Neither killed nor live-virus vaccines affect the safety of breast-feeding for either mother or infant. Breast-fed infants can be vaccinated on a regular schedule.

SEE ALSO: Hepatitis, Preventive care

Suggested Reading

  • Keusch, G. T., & Bart, K. J. (2001). Immunization principles and vaccine use. In E. Braunwald, A. S. Fauci, D. L. Kasper, S. L. Hauser, D. L. Longo, & L. J. Jameson (Eds.), Harrison’s principles of internal medicine (15th ed., pp. 780-789). New York: McGraw-Hill.

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