Yet there is a way to give yourself protection from bacterial pneumonia.

By itself, this will go a long way toward reducing your risk of dying from bird flu, if there's an influenza pandemic and you catch the H5N1 virus.

We don't have exact figures for causes of death of victims of the current bird flu, but we know that pneumonia and related bacterial diseases were listed as immediate cause of death on close to half of U.S. Spanish flu victims in 1918.

What is pneumonia -- your lung's alveoli become inflamed and flooded with fluid. The alveoli are the tiny sacs that transfer oxygen from the air you breathe into your blood stream.

Therefore, pneumonia attacks your body's ability to get oxygen into your blood so that it can be used. Since without oxygen we die, pneumonia is a potentially life-threatening problem.

Pneumonia is also a frequent complication of ordinary seasonal influenza, and together, they're the seventh most common cause of death in the United States. That makes them the most common infectious disease cause of the death in the U.S.

There're over 30 causes of pneumonia, but the most common types of pneumonia are caused by bacteria and viruses. These are also the most common type of pneumonias that take advantage of victims weakened by bird flu.

First, the bad news -- there is no protection against viral pneumonia. It can be treated somewhat with some antiviral drugs, but those will be in short supply during a bird flu pandemic. Ordinarily, about half of all cases are viral pneumonia. But it is actually less severe than bacterial pneumonia. Whether that would remain true for bird flu patients, we just don't know -- and hope we won't ever find out.

The good news is that there is a vaccine which will train your body's immune system to fight the common types of bacterial pneumonia.

Most cases of bacterial pneumonia are caused by the pneumococcal bacterium (also called Streptoccoccus pneumoniae). In children, it also causes sinusitis and ear infections. When it infects the lungs, it's pneumococcal pneumonia.

In the 20th century, death from pneumococcal bacterium was severely reduced in developed countries due to penicillin and other antibiotics. However, many strains of the pneumococcal bacterium and other bacteria that can cause pneumonia are now resistant to antibiotics.

There're over 200,000 cases of pneumococcal pneumonia a year in the United States, and it causes about 40,000 deaths, so the mortality rate is 20%. However, about half of the people who catch pneumonia caused by methicillin-resistant Staphylococcus aureus (MRSA) bacteria, while on a ventilator, will die.

The vaccine for pneumococcal pneumonia is called Pneumovax. It contains material from the 23 most common strains of pneumococci bacteria. (No living bacteria.) It's effective in about 80% of adults. It's a 23-valent polysaccharide vaccine.

For children, there's Prevnar or PCV7 -- a 7-valent conjugate vaccine.

Ordinarily, Pneumovax is recommended for adults most at risk of pneumonia. Those over 50, with AIDS, with an organ transplant, undergoing cancer treatment or other immune-compromised. Also, people with Alzheimer's, cystic fibrosis, emphysema, alcoholism -- and people who smoke tobacco.

People who are in the hospital for any reason are also at higher risk of catching pneumonia -- a sad comment on our modern system.

Remember, however, that vaccines do NOT themselves provide you with any protection. Basically, they train your immune system how to fight a particular enemy.

They're only as effective as your immune system is strong.

If your immune system is weak and undernourished, it can't fight disease no matter how well trained.

Therefore, you should not rely on vaccines. You should do your part to keep your immune system strong. Eat healthy foods, get regular moderate exercise, take nutritional supplements, reduce stress and get plenty of sleep.

So if you're at all concerned about the risk of a bird flu pandemic, and especially if you're in one of the high risk groups, ask your doctor about Pneumovax now -- before it's too late.