For example, two vaccines are made by only one company.
The vaccine will also be made available to the general public in 2004, for those who want to take it.
A new vaccine would be made with more modern methods.
Scientists have tried to make such vaccines for decades, without success.
A weaker but safer vaccine may be made for those at risk.
By early 2003, the government expects to have enough vaccine made from a new technique to protect every American.
At the same time, however, prices aren't high enough to persuade drug companies to make existing vaccines and find new ones.
The government cannot force companies to make vaccines, however.
That is one reason the drug companies until now have been reluctant to make vaccines for the Pentagon.
The vaccine, given in the second year of life, is made with live, but weakened, viruses.