Assertion: smallpox's virus | /r/HasProperty | cowpox
Facets:
value: at some point
type: TEMPORAL
value: no longer
type: TEMPORAL
Source sentences:
text: At some point, the virus in use was no longer cowpox, but vaccinia.
text: In the late 18th-century, a British doctor named Edward Jenner discovered that milkmaids infected with a milder virus called cowpox seemed immune to smallpox.