preventive measure; precautionary measure
A measure taken in advance to prevent something undesirable from happening. Used in contexts like health, security, and disaster prevention.
As a preventive measure against the flu, I'm thorough about washing my hands and gargling.
We need to take precautionary measures against earthquakes.
対策 is a broader term for countermeasures or measures to deal with a problem, not necessarily preventive. 予防策 specifically emphasizes prevention.
Compound of 予防 (prevention) + 策 (plan, measure).