Preventive approaches that have proven valuable in community-acquired pneumonia include pneumococcal and influenza vaccines. In nosocomial pneumonia, there is no systematic approach to prevention that has been proven effective, but there are multiple experimental approaches in limited use.

Pneumococcal vaccine is effective and should be given to patients who are older than 65 years, have chronic heart or lung disease, have other chronic medical illnesses, reside in chronic care facilities, or who have immunosuppressive illnesses such as Hodgkin’s disease, chronic lymphocytic leukemia, multiple myeloma, and HIV infection. In addition, those with splenic dysfunction, caused by splenectomy or illness (such as sickle cell anemia), should be vaccinated to prevent overwhelming pneumococcal pneumonia and sepsis. The efficacy of the vaccine has been proven in case-control studies to be 60% to 70%; its efficacy may be greater if the vaccine is given to patients earlier in the course of chronic illness. The protective efficacy may wane in patients with immunosuppressive illness and in others with chronic disease who may not sustain high levels of antibody for prolonged periods; these individuals should be revaccinated after 6 years. One potentially effective application of the vaccine is its use as part of a hospital-based program, because up to 60% of all patients admitted for community-acquired pneumonia have been hospitalized for some reason in the preceding 4 years. Thus, if all hospitalized patients are considered for vaccination before discharge, immunizations will be given to a clearly high-risk population.

Influenza vaccine should be given to patients who qualify for pneumococcal vaccine because of chronic medical illness, advanced age, or immunosuppressive illness, but it does not need to be given to patients whose only indication is splenic dysfunction. Influenza vaccine must be repeated yearly and is effective only if given in the late fall in anticipation of the high-risk period. Efficacy in preventing deaths has been reported to be as high as 80% in the nursing home elderly population. Others who also qualify for influenza vaccine include those who can transmit the illness to high-risk individuals as well as those with high levels of exposure. Thus, health care workers, those who provide care to or live with chronically ill patients, and those who work in day-care centers should be immunized.

There are no other vaccines that are of proven efficacy in community-acquried pneumonia. Haemophilus influenzae type b vaccine has prevented pediatric meningitis and other invasive infections due to this organism, but it is not routinely recommended for adults. However, use of this vaccine should be considered (although not absolutely recommended) in certain high-risk adults such as those with HIV infection, those with an organ transplant, those receiving immunosuppressive therapy, patients with certain hematologic malignancies, and patients with anatomic or functional asplenia.

The 65-year-old man with chronic obstructive pulmonary disease in the spring should receive pneumococcal vaccine, but influenza vaccine should not be given until the fall. The 37-year-old woman who has had a splenectomy is otherwise well, has already electively received Haemophilus influenzae type b vaccine and now only needs pneumococcal vaccine. The 68-year-old man and 45-year-old woman should receive only influenza vaccine. The 68-year-old man qualifies because it is the fall, he has chronic cardiac disease, and he does not need pneumococcal vaccine at this time because he received it 4 years ago. The woman working in a nursery school, who is being seen in the fall, should be immunized against influenza because of her high level of exposure to infection.