[RobertG (OP)]

Is asymptomatic infection possible or is it myth? I've seen that many high end scientists say it doesn't happen, and Doctors would have learnt as much in their first year studies, but it now seems to be accepted by much of the medical community. It seems to me that the current phase of multiple testing of asymptomatic people, particularly children doesn't make any sense. Why, if you feel well, should you be tested for C19, or colds or flu or anything. Why not take it a step further.eg  My leg feels fine but let's Xray it anyway to see if it's broken?

[alancalverd]

All infectious disease has an asymptomatic period whilst the infection grows without significantly impairing the patient's function. Covid is just remarkable in having a fairly  long period in which the patient is incubating and dispersing virus but does not complain of any effects.

If you have been in close contact with an infectious person, it is quite likely that you have acquired the infection even if you don't feel ill, so it is worth testing both known contacts and those who, if infectious, will infect large numbers of others (e.g. in an aeroplane or a dental surgery). But the guy sitting next to you with a broken leg will not break yours.