Thats been my assumption - its a race between the virus finding the right spot that allows access to the cell and something else destroying it. Either the coron

Thats been my assumption - its a race between the virus finding the right spot that allows access to the cell and something else destroying it. Either the corona virus needs a very specific spot to allow access, or there's a number of steps that have to occur before a successful infection. Either case requires a lot of virus particle to infect for the probabilities to be in its favour.