1.   Attenuated virus vaccines, like the Sabin oral polio vaccine, are similar to the disease-causing versions except that they have lost the genetic capacity for virulence.

2.   But he and other experts said much more research was needed to be sure that such an attenuated virus vaccine was both safe and effective.

3.   Distraught neighbors have been administering the duck virus enteritis vaccine themselves.

4.   Dead virus vaccine causes fewer cases of polio.

5.   Salk never lost faith in killed virus polio vaccine and continued to champion its cause all his life.

6.   Since it is not a live virus vaccine, like the smallpox vaccine, it cannot give a person ebola.

7.   The new policy is aimed at eliminating the handful of polio cases each year that are caused by the live virus vaccine.

8.   The live virus vaccine promised lifetime immunity, while the original Salk vaccine did not.

9.   It also urges accelerated research into a West Nile virus vaccine and a national web site to keep the public and media informed.