1.   But since the vaccine offers protection if administered during the first several days after exposure, a prepared city could immunize almost everyone in time.

2.   DNA vaccines offer many practical advantages.

3.   Scientists and public health officials have long known that a vaccine offers the only long-term hope of conquering AIDS.

4.   The vaccine offers the hope that Hib-related diseases can be virtually eliminated.

5.   Unlike the antibiotics used to treat potential anthrax exposures in recent weeks, the vaccine offers lasting protection before exposure.

6.   Vaccines offer little help, veterinarians say.

7.   The upcoming tests are expected to show whether the vaccines can offer real protection against the virus.