Mr. Bush says he'll be given the vaccine because he doesn't want to ask military personnel to do something he wouldn't do himself.
"As commander in chief, I do not believe I can ask others to accept this risk unless I am willing do to the same," Mr. Bush said. "Therefore, I will receive the vaccine along with our military."
He says, however, that his family and his staff won't be getting the vaccine -- because health experts say it's not necessary for the general public to do so.
"Our government has no information that a smallpox attack is imminent, yet it is prudent to prepare for the possibility that terrorists who kill indiscriminately would use disease as a weapon," Bush said.
The first to get the vaccine will be U.S. military personnel serving in high-risk areas.
Mr. Bush is also asking that emergency medical workers and others who would respond first to a smallpox attack get vaccinated, but strongly suggested the general public not take the inoculations, which come with health complications.
"Given the current level of threat and the inherent health risks of the vaccine, we have decided not to initiate a broader program," he said.
The program calls for mandatory smallpox shots for 500,000 military personnel, starting next month. Vaccinations will also be recommended for about half a million civilian emergency workers.
By 2004, when there will be enough licensed vaccine for every American, the administration plans to have a process by which any American without disqualifying conditions can get it.
Educating the public about the vaccine - its risks vs. benefits - will be a major focus. Millions of Americans could be put in harms way if the smallpox vaccine is used unwisely. For a medical community whose primary goal is to "do no harm" the reintroduction of the smallpox vaccine presents many challenges.
The smallpox vaccine is so risky that doctors agree it would never receive FDA approval today. One in a million people who get vaccinated will die, but in the face of emerging bio-terror threats, it remains the only protection there is, reports CBS News Medical correspondent Elizabeth Kaledin.
In preparation for the president's decision to order vaccinations and to "re-acquaint" themselves with the side effects, doctors have been giving shots to volunteers. At a Vanderbilt University test site, 148 people got the vaccine.
"I had headache, joint pain, muscle pain, swelling of my shoulder and my lymph node, and fever that got all the way up to 103," student Mark Harris told Kaledin.
In fact, everyone in the trial got a blister on their arm. Sixty to seventy percent had itching at the lesion. Thirty percent had redness and swelling. Ten percent and flu and fever, 5 percent had to miss class or work and one person was hospitalized.
Doctors say those reactions are exactly what they saw historically, and what the public should expect today:
"I think it's a very worthwhile and effective vaccine -- it's just we're not used to it like we used to be," said Dr. Tom Talbott.
In fact, vaccinations have become so routine and basically pain free for Americans, infectious disease experts say many will be taken aback by the side effects.
"Now that we have only intimations of danger but there's no real disease, a lot of people have questions about whether the pain is worth the gain," noted Dr. William Schaffner
Adding to the risk, the overall health profile of Americans has changed, and today there's a much greater population who cannot tolerate the vaccine's dangers:
Based on studies from the 1960s, experts estimate that 15 out of every 1 million people vaccinated for the first time will face life-threatening complications, and one or two will die. Reactions are less common for those being revaccinated.
Using these data, vaccinating the nation could lead to nearly 3,000 life-threatening complications and at least 170 deaths.
Smallpox, once among the most feared diseases on Earth, killed hundreds of millions of people in past centuries, but it hasn't been seen in this country since 1949 and was declared eradicated worldwide in 1980. But experts fear that it could be used by hostile nations or terrorist groups in an attack.
Routine smallpox vaccinations ended in the United States in 1972, meaning nearly half the population is without any protection from the virus.
The immune status of those who were vaccinated more than 29 years ago is not clear. Because the antibodies have been shown to decline substantially during a five- to ten-year period, even those who received the recommended single-dose vaccination as children do not have lifelong immunity. The U.S. has 15.4 million doses of vaccines, boxed and prepared to deliver if there is a breakout.