PREVENT / block / barrier / protect:
(On YouTube at: https://youtu.be/WpNppF_EIgw )
The sign for "prevent" can also be used to mean "block" or "protect."
You could even combine it with a sign like "INJECT" or "take-PILL" to create the meaning "inoculate."
PREVENT / BLOCK / PROTECT:
PREVENT / block / barricade / prevention / protect / protection:
Notes: