Patient information: Adult immunizations
Patricia Hibberd, MD, PhD
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INTRODUCTION — For many of us, the term "routine immunizations" immediately makes us think of our children‘s needs. And, fortunately, pediatric immunization programs in the United States have been quite successful. Due to a routine series of vaccinations against a range of contagious diseases such as measles, rubella, tetanus, diphtheria, and poliomyelitis, fewer than 500 children die each year of vaccine preventable diseases.
Yet we may tend to forget that healthy adults also require regular immunizations to help protect against certain infectious diseases. In fact, only about 46 percent of people over age 65 and 12 percent of people at risk aged 18 to 49 years have received the pneumococcal vaccine, which protects against the most common cause of bacterial pneumonia. Similarly, only 64 percent of older adults receive annual flu immunizations, and only 20 percent of younger adults at risk do so. As many as 50,000 to 70,000 adults die annually of these two vaccine preventable diseases alone. Thus, receiving appropriate immunizations plays a crucial role in protecting your health throughout your lifetime. The following is a general discussion of immunizations and those that are currently recommended for the routine care of healthy adults.
HOW DO IMMUNIZATIONS WORK? — There are two main types of immunizations — active and passive. Active immunizations use whole or portions of microorganisms to cause the individual to form antibodies (proteins that the body makes) that protect against later infection. Antibodies themselves in the form of immunoglobulin are used for passive immunization. This may prevent infection sooner than the time required for the body to make its own antibody, but the protective effect wears off.
Active immunization — With active immunization, a harmless form of a disease-causing organism is introduced into the body, stimulating the immune system to produce appropriate antibodies against that invading organism. If a person is later exposed to the same infectious agent (pathogen) against which the vaccine is directed, the immune system recognizes the foreign agent, rapidly producing the specific antibodies required to destroy the pathogen. This secondary response protects the individual from developing the infectious disease (ie, providing active immunity), ideally for life. However, some vaccines require "booster" shots to maintain immunity.
Vaccines for active immunization — Some vaccines used for active immunization are called live vaccines, because they are derived from altered, weakened (attenuated) forms of bacteria or viruses. Others use killed whole bacteria or noninfectious parts of the organisms capable of inducing an immune response. Vaccines recommended for healthy adults include the pneumococcal, influenza, measles-mumps-rubella (MMR), varicella, hepatitis B, and hepatitis A vaccines. (For more, see below).
Toxoids for active immunization — Toxoids are vaccines made from the toxins of bacteria that are modified to eliminate their toxic effects. However, they retain their ability to stimulate the production of antibodies. Toxoids recommended for healthy adults include those administered to provide immunity against tetanus and diphtheria. (For more, see below).
Passive immunization — With passive immunization, temporary immunity can be provided through the administration of a concentrated preparation of antibodies obtained from a large pool of donors (known as immune serum globulin). Passive immunization offers short-term protection to people who have been or will be exposed to a specific pathogen. It is typically used for patients with weakened immune systems (immunocompromised patients) who are unable to produce an effective immune response with active immunization. Passive immunization is not routinely recommended for healthy adults since most individuals are able to produce antibodies through active immunization, which provides more durable immunity. However, passive immunization is occasionally used for pregnant women, healthcare workers, international travelers, or others. Situations in which passive immunization might be employed include:
* Following exposure to an infectious agent where infection would be expected to result before the approximately 10 to 14 days necessary to make an antibodies to an active vaccine.
* Following exposure to a particular agent for which a vaccine is not available. Hepatitis A used to be such a pathogen and gamma globulin shots were commonly given to travelers; now travelers receive a specific hepatitis A vaccine.
* To individuals who did not develop an immune response to an active immunization (ie, "non-responders") and are at high risk for exposure or have been exposed to the pathogen.
WHAT SIDE EFFECTS CAN RESULT? — Most vaccines and toxoids cause only minor side effects, with most patients tolerating them well. In fact, the more common problem is when a patient misses the opportunity to receive a recommended immunization due to misconceptions about its safety. Thus, if you are reluctant to receive a recommended vaccine, it is essential that you share any questions with your doctor so that he or she can address your concerns.
Mild side effects — With many vaccines and toxoids, side effects can include:
* A mild fever
* A reddish, tender area at the site of injection
* Occasionally, a "serum sickness-like" reaction that may be characterized by fever, skin rash, swollen lymph nodes, joint pain, and/or other symptoms
Severe side effects and contraindications — Severe side effects that make specific vaccinations inadvisable (contraindicated) are rare. Such contraindications include severe neurologic reactions (eg, seizures) following a prior vaccine or severe allergic reactions (eg, anaphylaxis) to certain substances. As examples, particular vaccines are contraindicated for people who have had a previous anaphylactic reaction to:
* Eggs or egg protein, since the vaccine preparation process includes the use of embryonic chicken eggs or cultures in some cases (eg, measles, mumps, influenza vaccines). Minor allergies to eggs do not exclude receiving these vaccines.
* The antibiotic medications neomycin or streptomycin (since the MMR vaccine, for example, contains trace amounts of neomycin)
* A specific vaccine itself, which would prevent revaccination due to the risk of recurrence.
In addition, administration of live virus vaccines, including the MMR and varicella vaccine, may also be contraindicated for:
* Immunocompromised patients, since there is an increased risk of viral replication
* Patients who have recently received immune serum globulin, which can delay the normal response to active vaccination
* Women who are pregnant or considering becoming pregnant within the next few months, due to the potential risk to the developing fetus.
Thus, a complete patient history is essential to enable doctors to determine appropriate immunizations in your specific case. Such a patient history should include any current or past medical conditions, known allergies, medication history, adverse reactions to specific drugs or vaccines, and current or planned pregnancy.
Conditions that are NOT contraindications — As mentioned above, true contraindications to vaccination are rare. Accordingly, it is important to note that the following are not contraindications to immunization:
* Current or recent mild illness, with or without low grade fever
* Current or recent antibiotic therapy
* Previous mild to moderate tenderness, redness, or swelling at the site of injection or fever less than 40.5ºC after any previous vaccination
* A personal history of allergies, except those listed above
* A family history of adverse reactions to immunization
Again, it is essential for patients to share any concerns with their doctors regarding a particular vaccine, rather than simply avoiding or missing the opportunity to take an important measure to protect their health. If you have received a vaccine and develop symptoms that you think could be related to the immunization, you should contact your doctor. There is a national Vaccine Adverse Events Reporting System (VAERS), which your doctor can access if necessary. Occasionally, recommendations for changes in vaccine administration have resulted from such reports.
WHAT VACCINES ARE RECOMMENDED FOR HEALTHY ADULTS? — Immunization recommendations for healthy adults in the United States are based on policies developed by the Advisory Committee on Immunization Practices (ACIP), affiliated with the Centers for Disease Control and Prevention (CDC) . ACIP statements and additional information concerning immunization can be obtained from the CDC‘s Immunization Hotline (at 1-800-232-2522) or downloaded from the CDC‘s web site (www.cdc.gov/mmwr/PDF/wk/mm5345-immunization.pdf). These immunization recommendations are categorized by age:
* 19 to 49 years
* 50 to 64 years
* 65 years and older
In addition, the recommendations include:
* Routine immunizations by vaccine and age group
* Immunizations for "at risk" adults by vaccine
Such recommendations are directed toward providing or maintaining immunity against certain infectious diseases to lower their prevalence and to help prevent their spread in the community. In addition, as noted, certain vaccines are recommended for particular groups of at risk adults, such as those with an increased risk of becoming seriously ill if they develop particular infections, such as elderly individuals, people with certain long-standing (chronic) diseases, and/or immunocompromised patients
It is also recommended to immunize those with an increased risk of developing certain infections (and/or transmitting them to at risk individuals) due to their:
* Residential circumstances, such as residents of long-term care facilities (LTCF, including nursing homes), young adults residing in college dormitories, household members living with at risk individuals, or inmates in correctional facilities
* Work situations, such as healthcare or public safety workers, laboratory staff, day care center workers, or food handlers
* Travelers to particular countries
* Lifestyle circumstances or choices, such as individuals who engage in homosexual sex, have sex with multiple partners, or use injection drugs
Specific immunizations — According to these recommendations, vaccinations for healthy adults should include the following :
Pneumococcal — Pneumonia can be a serious lung infection, which can be fatal especially in elderly people, individuals with underlying medical conditions, and immunocompromised patients. Pneumonia is most frequently caused by bacteria and the most common one of these is Streptococcus pneumoniae or pneumococcus. Pneumococcal pneumonia can develop as a complication of upper respiratory tract viral infection or influenza.
The pneumococcal vaccine is protective against many of the 23 types of pneumococci. Such protection has become more critical with the emergence of strains of S. pneumoniae that are resistant to penicillin. Accordingly, current guidelines recommend the pneumococcal vaccine routinely for all healthy elderly people aged 65 years or older and others at risk. These include individuals with certain chronic conditions (eg, diabetes mellitus, heart and lung disease, alcoholism, or liver failure), immunocompromised patients, people living in special environments (eg, residents of LTCF) or certain ethnic groups (eg, Alaskan natives, certain American Indian populations).
All adults in these categories should have one dose of the vaccine given at age 65 years, unless they had the vaccine administered when aged 60 to 64. Those aged 2 to 64 years who have a chronic illness or live in special environments should receive the vaccine when the need for immunization is recognized; at age 65, they should receive a one-time revaccination. First-trimester pregnancy is a relative contraindication for the vaccine.
Influenza — Commonly known as flu, influenza is a highly contagious viral infection that occurs in outbreaks worldwide, usually in the winter season in the United States. In many cases, patients gradually improve over about two to five days, although the illness may last for one week or more. However, bacterial pneumonia is a common complication among at risk patients (eg, elderly individuals, residents of LTCF, people with certain chronic conditions, such as heart, lung, or kidney disease or diabetes, and immunocompromised patients).
Influenza is caused by influenza A or B viruses. The influenza virus is able to cause regular outbreaks due to its ability to frequently change its proteins, producing new strains. Thus, new vaccines are produced every year, based on the strains circulating in the world; they are prepared from highly purified, inactivated influenza A and B virus strains that cannot cause infection. Annual immunization is also necessary due to the fact that immunity declines during the year following vaccination and circulating strains change from year to year.
According to current guidelines, the annual influenza vaccine (administered in the fall) is recommended as a routine immunization for all people aged 65 years or older as well as those under age 65 who are at risk of complications from influenza infection. These include residents of LTCF; adults with chronic disorders, such as heart and lung disease, including asthma, diabetes, or kidney dysfunction; immunocompromised adults; and pregnant women who will be in the second or third trimester during flu season.
The annual vaccine is also recommended for people who could transmit influenza virus to at risk people. These include doctors, nurses, and other hospital personnel; employees of LTCF; people who provide home care to at risk individuals; and household members of at risk persons.
The recommended "target" populations for influenza and pneumococcal vaccine overlap. Fortunately, the vaccines can safely be administered simultaneously at different sites, without altering their effectiveness. Medicare Part B reimburses for both the influenza and pneumococcal vaccine.
Healthy adults aged 19 to 49, who do not have high risk conditions and who are in contact with immunocompromised persons, can receive either the inactivated vaccine or the intranasally administered vaccine (FluMist).
Tetanus and diphtheria — Tetanus is a wound infection caused by a bacterial toxin; the bacterium, which resides in soil and the intestinal tracts of certain mammals, enters the body through a wound, multiplies, and produces toxins that act on nerves controlling muscle activity. Diphtheria is a sudden (acute) illness caused by a bacterium that is usually transmitted via droplets coughed or sneezed into the air. The bacteria typically multiply in the throat and may release a toxin into the bloodstream, which can lead to damage of the brain and heart.
Both of these diseases are rare in the United States. However, almost all cases are diagnosed in adults who never completed the standard childhood vaccination series. Elderly individuals may also have an increased risk of developing both diseases due to a decline in protection against tetanus to less than 30 percent in adults over age 70 and against diphtheria to less than 20 percent in adults over age 60. The same adults tend to lack protection against both diseases.
As noted, people with an increased risk of developing these diseases are those who never completed their childhood (primary) immunization series, including elderly adults, those in rural populations, injection drug users, and immigrants. If there is any doubt about whether or not an adult has received the primary series, they should receive three doses of the tetanus-diphtheria (Td) vaccine, with the first and second doses separated by four weeks and the third given 6 to 12 months later.
In addition, due to waning immunity against the two diseases, Td boosters are recommended for all adults every 10 years for life. Experts indicate that an acceptable alternative is a final booster at age 50 only for adults who completed the primary series. Regardless of prior tetanus and diphtheria immunization, adults with an acute injury or wound must have their Td immunization status reviewed to ensure the administration of appropriate preventive measures.
Measles-mumps-rubella (MMR) — All of these infectious diseases are transmitted by infected patients who release airborne droplets from coughing or sneezing. Measles, a highly contagious viral illness of the respiratory tract, primarily affects children; it causes a distinctive rash, fever, and cough and may result in certain complications, including infection of the middle ear and lungs. Mumps, an acute, usually mild viral infection of childhood, is primarily characterized by painful swelling of the salivary glands; however, complications may sometimes result, including inflammation of protective membranes of the brain (meningitis) and swelling and tenderness of one or both testes (orchitis) in males affected after puberty. Rubella, also known as German measles, is a typically mild viral infection primarily characterized by fever, swelling of the lymph nodes, and rash; however, it can cause severe birth defects (congenital rubella syndrome) if the mother is affected during early pregnancy.
The incidence of these diseases fell dramatically in the United States with the introduction of the live virus vaccine. However, there have been brief resurgences, leading to a change in the routine childhood vaccination schedule (ie, from one to two doses of the combined MMR vaccine) as well as additional recommendations for at risk individuals (see below). In addition, despite the rarity of the diseases in the United States, continued protection of children as well as adults remains essential for a number of reasons:
* Cases of measles imported from other countries still have the potential to serve as a major source of future exposures unless the population remains immune.
* Adults with measles have an increased risk of mortality compared with older children; in addition, measles during pregnancy is associated with early labor and miscarriage.
* The most serious complications of mumps arise more frequently in adults than children, including orchitis leading to sterility, neurologic complications, and risk of fetal death if the infection is acquired in early pregnancy.
* To help eliminate the most important consequences of rubella, including miscarriage, fetal death, and congenital rubella syndrome.
According to current guidelines for healthy adults, the MMR vaccine is recommended for those with an increased risk of exposure to or illness from infection with measles, mumps, and rubella. These include women of childbearing ages (however, MMR should not be administered to pregnant women or women considering pregnancy in the next 28 days), college students, healthcare workers, and international travelers.
Such high risk individuals must have full immunity to all three diseases. Immunity can be documented by a record of two doses of the MMR vaccine, a blood test showing immunity, or birth before 1957 (except for women who could become pregnant). If such criteria are not fulfilled, high risk adults should receive two doses of MMR vaccine (separated by at least 28 days).
Adults without an increased risk of exposure to the three diseases still require full immunity; however, documentation of one dose of the MMR vaccine after age one year may meet the criterion for adequate immunization. If there is any doubt concerning the adequacy of immunity, adults who do not have an increased risk of exposure should receive one dose of MMR vaccine. Also, because adults who received the measles vaccine between 1963 and 1967 were vaccinated with inactivated measles vaccine, they should have one more dose of the live, attenuated measles vaccine; some experts recommend that all adults born after 1956 should be immunized.
Varicella — Also known as chickenpox, varicella is an acute, highly contagious viral illness caused by infection with the varicella zoster virus (VZV). The disease is primarily characterized by fever, sore throat, and a distinctive, itchy, blistering rash that later forms scabs. The virus is transmitted by the spread of airborne droplets or direct contact with skin lesions. In some cases, complications may include secondary bacterial infections of the skin, pneumonia, or, less commonly, inflammation of the brain or other findings.
Although varicella is primarily a childhood disease, about 10 percent of adults are susceptible to infection; adults have an increased risk of lung and neurologic complications. Varicella may also be severe or potentially life-threatening in immunocompromised patients. In addition, varicella infection during the first half of pregnancy can cause severe birth defects (eg, congenital varicella syndrome).
A varicella vaccine consisting of live weakened VZV has been available since 1995 and has been added to the childhood immunization schedule. According to current guidelines regarding adult immunizations, varicella vaccine is predominantly recommended for at risk adults. These include:
* Healthcare workers
* Close contacts of immunocompromised patients
* Teachers of young children
* Day care employees
* Susceptible young adults in closed or relatively closed populations, such as colleges, military bases, or correctional facilities
* Women of childbearing ages; however, varicella vaccine should not be administered to pregnant women or women considering pregnancy in the next month
* International travelers
Either a reliable history of varicella infection or a positive blood test is considered sufficient evidence of immunity. Susceptible adults who have no contraindications to vaccine administration should receive two doses, with the second dose administered four to eight weeks following the first. Contraindications include pregnancy that is current or planned and individuals with a history of anaphylactic reactions to neomycin or gelatin.
Hepatitis B — Inflammation of the liver (hepatitis) is commonly caused by infection with certain viruses, including hepatitis B virus (HBV). Although the infection often resolves or does not produce symptoms (asymptomatic), HBV can result in chronic infection that can lead to progressive liver scarring (cirrhosis) or liver cancer. HBV is transmitted by contact with an infected individual‘s body fluids, such as by unprotected sexual intercourse, the sharing of contaminated needles during injection drug use, or contact with contaminated blood or blood products. HBV can also be transmitted from a pregnant woman to her baby.
More than 100,000 people, mostly adults, are infected with HBV each year in the United States. Although the overall lifetime risk of acquiring HBV is only about 5 percent for the average person, the risk increases to almost 100 percent in the highest risk groups.
Two genetically engineered (recombinant) vaccines are now available that are protective against HBV. Although HBV infection has decreased among healthcare workers and homosexual males in the United States, there has been an increase in cases due to injection drug use and heterosexual exposure. Because it is difficult to ensure immunization of vulnerable adults, and since about 30 to 40 percent of infected individuals have no identifiable risk factor, HBV vaccination is now recommended for all children in early childhood or as a "catch-up" immunization during early adolescence. However, it will be many years before most young adults will have been vaccinated against HBV.
According to current guidelines for adults, all susceptible high risk adults should receive HBV vaccine, provided in three doses, with the second and third doses administered at one month and six months following the initial dose. Adults at increased risk of HBV exposure include: healthcare and public safety workers, personnel in institutions caring for the developmentally disabled, inmates of correctional facilities, injection drug users, and patients undergoing kidney dialysis. Additional at risk adults include household contacts and sex partners of people with chronic HBV, individuals with multiple sex partners, people with sexually transmitted diseases, homosexual men, patients who receive blood clotting factors, people from countries where HBV is consistently present (endemic), and certain international travelers. Contraindications for HBV vaccine include anaphylactic reactions to yeast.
Hepatitis A — Hepatitis due to infection with the hepatitis A virus (HAV) is the third most common infection in children and adolescents in the United States; it ranks fifth or sixth in adult males and females respectively. HAV infection often causes no apparent symptoms in children. By contrast, infection in adults can vary in severity from a mild flu-like illness to rapidly progressive, extremely severe (fulminant) hepatitis; the latter is rare. The most common symptoms and findings include flu-like illness; abnormal yellowish discoloration of the skin, mucous membranes, and whites of the eyes (jaundice); and enlargement of the liver (hepatomegaly). Life-threatening illness increases among adults over age 50 years and those with chronic liver disease, who can develop fulminant HAV.
HAV is present in the stool of infected individuals. Spread most commonly occurs by exposure to feces from improperly washed hands to the mouth or contaminating food or water. When a risk factor can specifically be identified, most cases result from contact with an infected individual, frequently a household member. Additional cases occur among employees and children in day care centers, in international travelers, and due to recognized food or waterborne outbreaks. As with HBV, about 40 percent of affected adults have no known risk factors for contracting HAV.
Two inactivated vaccines that are protective against HAV are available for use in the United States, HAVRIX and VAQTA. They are provided in two doses, with the second dose administered 6 to 12 months following the first for HAVRIX and 6 to 18 months for VAQTA. VAQTA was recalled in the fall of 2001 because some prefilled syringes did not contain the proper amount of antigen to produce a reliable amount of antibody. If you have already been vaccinated against hepatitis A, you should contact your doctor to find out which vaccine you received.
The HAV vaccine is recommended for susceptible at risk adults, including travelers to countries where HAV is endemic; injection and non-injection, illegal drug users; homosexual men; patients with chronic liver disease; adults with blood clotting factor disorders; adults with an occupational risk for infection; day care center staff; personnel in institutions for the developmentally challenged; and food handlers. Pregnancy is a relative contraindication for HAV vaccine.
Meningococcal — The bacteria that causes meningococcal disease (Neisseria meningitides) is one of the most important causes of bacterial meningitis in the United States. The bacteria lives on surfaces of the nasopharynx and is transmitted from person to person by direct contact with the respiratory secretions of patients or people who carry the bacteria without symptoms. Although meningococcal disease is easily treated, it is important to prevent the disease because 10 to 14 percent of people die from the disease (CDC estimate, 2004). Most of the meningococcal cases in adults are caused by Neisseria meningitides serogroups (C, Y, or W-135). These serotypes are included in the available vaccines.
In January 2005, the new meningococcal vaccine became available - the meningococcal tetravalent polysaccharide vaccine (MCV4). It was approved for use in people 11 to 55 years of age. Each dose includes the A, C, Y, W-135 serotypes. Based on the safety and effectiveness of this new vaccine, the CDC‘s Advisory Committee on Immunization Practices (ACIP) now recommends routine vaccination of adolescents, college freshmen living in dormitories, military recruits, travelers going to areas where meningococcal disease is hyperendemic or epidemic, microbiologists who are exposed to isolates of Neisseria meningitidis, patients without a functional spleen, and patients with terminal complement deficiency. The vaccine can be used in adults infected with human immunodeficiency virus (HIV). The CDC does not yet know whether revaccination with the MCV4 vaccine will be needed. For adults over 55, the previously available meningococcal tetravalent polysaccharide vaccine can be used, but revaccination for people at high risk every 3 to 5 years is recommended.
THE BOTTOM LINE — All adults should speak with their doctors concerning which immunizations are specifically recommended in their case. Numerous factors will need to be considered in such an assessment. Thus, as noted above, patients should provide a complete patient history, as well as any additional information that may affect their risk for certain infections, including residential circumstances, occupation, upcoming travel plans, and lifestyle circumstances or choices.
WHERE TO GET MORE INFORMATION — Your doctor is the best resource for finding out important information related to your particular case. Because every patient is different, it is important that your situation is evaluated by someone who knows you as a whole person.
This discussion will be updated as needed every four months on our web site (www.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information. Some of the most pertinent include:
Patient Level Information:
Avoiding infections in pregnancy
General travel advice
Immunizations for travel
Professional Level Information:
Approach to immunizations in healthy adults
Immunizations for healthcare workers
Immunizations for travel
Immunizations in HIV-infected patients
Standard childhood immunizations
A number of other sites on the internet have information about the immunizations. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.
* National Library of Medicine
* National Institute of Allergy and Infectious Diseases
NIAID Office of Communications and Public Liaison
Building 31, Room 7A-50
31 Center Drive MSC 2520
Bethesda, MD 20892-2520
* Centers for Disease Control and Prevention (CDC)
1600 Clifton Road
Atlanta, Georgia 30333
Phone: (404) 639-3534
Toll-free: (800) 311-3435
* National Coalition for Adult Immunization
4733 Bethesda Avenue, Suite 750
Bethesda, MD 20817-5228
Tel: (301) 656-0003
Fax: (301) 907-0878