| Search set | CIDG SRa | CENTRAL | MEDLINE and EMBASEb | LILACSb |
| 1 | smallpox | SMALLPOX VACCINE | SMALLPOX VACCINE | smallpox |
| 2 | vaccin* | smallpox | smallpox | vaccin* |
| 3 | 1 and 2 | SMALLPOX | SMALLPOX | 1 and 2 |
| 4 | — | 2 or 3 | 2 or 3 | — |
| 5 | — | vaccin* | vaccin* | — |
| 6 | — | (4 and 5) or 1 | (4 and 5) or 1 | — |
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.