[nudephil (OP)]

We got this question sent in by Steven:

It has been said that in some instances, where symptoms were bad, the sick person had probably received a high viral load. Presumably this could be lots of close contact with sick people, or the receipt of a lot of fluid from an individual sick person.

Reversing this logic, the receipt of a lower viral load would generally make someone less sick.

If this is the case, doesn’t this make infection from surfaces almost a hypothetical rather than real risk? Does anyone know how many people genuinely became infected from surfaces, rather than direct transmission from one person to another through the air?

Even if there is a real risk of becoming infected via surfaces, wouldn’t it be a good thing for people to get low dose infections? In the absence of a vaccine, surely receipt of tiny doses of virus would be beneficial to build up herd immunity?

Can anyone help?

[alancalverd]

You don't receive a viral load, you develop it.

Problem with COVID is that the minimum infective dose may be very small indeed (in principle, one virus could do the job if it got lucky) and AFAIK there is no proven lasting immunity.

Herd immunity occurs when either there are enough vaccinated or recovered people (minimum seems to be 80%) and sufficiently few active  carriers that the risk of random infection is negligible, or when all those susceptible to infection have died before reproducing. The problem with COVID is that it preferentially kills the old, not the young, so we will not evolve genetic immunity for a very long time, and there won't be many of us left!