This is the 3621st most frequent Japanese word.
防ぐ
To prevent; to defend against.
Here, 防ぐ is used to mean 'prevent' or 'ward off an undesired event' (accidents).
事故を防ぐために安全対策を強化しました。
Safety measures were strengthened to prevent accidents.
In this usage, 防ぐ focuses on the idea of avoiding an illness or health condition.
風邪を防ぐには手洗いが重要です。
Washing hands is important to prevent catching a cold.
防ぐ in this context expresses the idea of blocking or repelling an intrusion.