Why infectious disease can disable a warship

How do navies handle infectious disease such as COVID aboard warships?

With difficulty, because confinement accelerates transmission and a serious outbreak can take the entire ship out of action.

Infectious disease control aboard a warship is intrinsically difficult because many people share a closed living and working environment. A measles-like outbreak could sideline a cruiser, while COVID demonstrated the same vulnerability in modern fleets. Earlier sailors also faced deficiency diseases and other illnesses capable of depleting a crew before combat. Cleaning, isolation where possible, sick-bay arrangements, and disciplined hygiene therefore protect combat readiness rather than merely personal comfort.