Q. My wife and I are both over 70 years of age and in reasonably good health. We have signed organ donor cards so that upon our demise all body parts may be used to help others.

We mentioned these plans to our physician, but he said that we were too old to be organ donors. Is this true?

A. Not necessarily. Age is only one factor for being selected as an organ or tissue donor. Although being over 70 may limit your chances of being a donor, your age doesn't automatically exclude you.

There are no firm age cutoffs for organ or tissue donation. Although different medical centers have different criteria, here are some general guidelines based on age alone:

Organ donation -- kidney, liver, heart, lung, pancreas, bone marrow -- cut-off ages range from a low of 50 to a high of 65.

Tissue donation -- eye/corneas, bone, skin -- low of 60, high of 75. But there are instances of people over age 100 donating their corneas and giving the gift of sight to another person.

At the time of death, each potential donor is evaluated individually. Certain diseases will generally disqualify any donor, no matter how old. These include various infections and cancers. Sometimes, an older person will make a better donor than someone half his age.

Approximately 20,000 people are waiting for an organ or tissue transplant. Your donation could certainly improve or save someone's life after you're gone. And even if you do not meet the criteria for organ or tissue donation, you can still donate your body to a medical school for teaching and research, no matter what your age.

For more information about organ and tissue donation, contact one of the following organizations: 1) American Council on Transplantation, 700 N. Fairfax St., Suite 505, Alexandria, Va. 22314; 2) The Living Bank, P.O. Box 6725, Houston, Tex. 77265 (1-800-528-2971); 3) The United Network for Organ Sharing, P.O. Box 13770, 1100 Boulders Parkway, Suite 500, Richmond, Va. 23225 (1-800-24-DONOR).

If you wish to make arrangements to donate your body for medical teaching and research, contact one of the local medical schools at Georgetown University, George Washington University or Howard University. You can also write to the Living Bank for more information about body donation.

Q. I recently received a vaccination against pneumonia. My doctor said I just had to have one shot -- no boosters. Does this vaccine give me immunity both against the viruses and the bacteria that cause pneumonia?

A. No. The vaccine you had, called Pneumovax, gives you immunity against only one type of bacterium. It doesn't protect you against viral pneumonia at all. But the germ it does guard against, known as Streptococcus pneumoniae or the pneumococcus, is the most common cause of bacterial pneumonia.

Pneumonia is infection of the lungs. Viruses cause most cases of pneumonia, and bacteria are second in line. The only vaccine we have against viral pneumonia is the well-known flu shot. Because the flu virus changes slightly year to year, you need to get a vaccine each year to keep up your immunity.

People whom physicians recommended get flu shots include:

Those over age 65.

People with chronic illnesses, especially heart or lung disease, who require regular medical visits.

Residents of nursing homes or other chronic care facilities.

Physicians, nurses and other health workers, as well as household members who may transmit flu virus infection to people with chronic illnesses who are at risk of complications from this infection.

The Pneumovax shot is a one-time vaccination against the pneumococcus germ. Pneumonia due to this bacterium strikes about 500,000 people each year and is a very frequent cause of death in the elderly. People in certain groups have an increased risk of this infection and it's recommended that they be vaccinated:

Those over age 50.

People with chronic, disabling conditions, such as heart failure, kidney failure, emphysema, chronic bronchitis, cirrhosis or diabetes.

People who drink excessive amounts of alcohol, which lowers resistance to infection.

People who've had their spleens removed, usually following an injury. The spleen helps the body fight against pneumococcal infection.

People with decreased immunity as a result of cancer or its treatment.

People living in closed communities, such as residential schools, nursing homes or other institutions.

People with sickle cell anemia. This disorder often damages the spleen, making it unable to help the body resist this infection.

Jay Siwek, a family physician from Georgetown University, practices at the Fort Lincoln Family Medicine Center and Providence Hospital in Northeast Washington. Consultation is a health education column and is not a substitute for medical advice from your physician.

Send questions to Consultation, Health Section, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071. Questions cannot be answered individually.