This is potentially misleading. Viral load is a significant factor in the seriousness of most infectious diseases. This is why you'll likely be ok if you pass a coughing TB patient in the street and inhale a few bacteria, but are much more prone to contract TB if you spend an entire day cooped up in a small room with the same coughing, infected individual.

This is thought to be why an unexpectedly high proportion of young, healthy doctors and nurses are getting seriously ill from Covid-19. Statically, you'd expect almost all of them to get mild disease.