How a doorknob can become part of a cold’s route
A rhinovirus does not need to multiply on a surface to travel. It can arrive there in tiny deposits of mucus or respiratory droplets, then transfer to someone’s fingers when they touch the spot. The virus has to reach the moist lining of the nose, eyes, or mouth to infect cells; skin itself is not the destination.
That makes the hand a link in the chain, not a guarantee of infection. Some virus may transfer from a surface to a finger, and some may then reach the face. Each step can reduce the amount that remains, so a surface being capable of holding viable virus does not mean every touch delivers an infectious dose.
Why ordinary habits interrupt the chain
The practical weak point is often the trip from hand to face. Washing with soap and water physically lifts away grime and virus particles; avoiding face-touching with unwashed hands can also break the route. Cleaning frequently touched surfaces helps reduce contamination, but it cannot prevent every deposit from arriving there in the first place.
The useful distinction is between persistence and transmission: a virus may remain viable while waiting, but it still needs a series of transfers—and access to susceptible cells—before that waiting room becomes an infection.
