Under twelves are now thought to be spreaders, because they so rarely have symptoms, nobody could know they have been infectious for one or more periods of time
Possibly the people who cannot comprehend statistics might educate themselves by listening to a few back issues of More or Less on Radio 4. (Statistical literacy is not necessarily widespread in the general population, nor among academics or even the wrong sort of scientist. One who once had a job for a chemical firm, and once went to university, has been given a page in a tabloid, essentially to spread disinformation, just as someone calling himself a doctor could usually be found to declare there is no harm in smoking) .
It would be factually justifiable to assert that the extent of Covid19 is known, and furthermore, that the extent of re-infection is known, only if something had happened at the start of the year, which did not: Either the whole population, or, more realistically, an extremely large and representative proportion of known individuals, should have been recruited on a basis of being re-tested weekly.
Because this did not happen, it is not possible to be sure if people with no symptoms were in fact infected. It is known, that random and group testing has shown the large majority of carriers are asymptomatic.
People who felt ill with flu like symptoms were not the most likely people to have had covid and recovered from it. People who felt absolutely fine would have vastly outnumbered them, would never have been tested, and therefore never be aware they had contracted the virus, and, probably, passed it on without ever knowing.
Neither they nor anyone else would, of course, have the least idea if they had been infected at all, infected twice, or infected more than twice, all without having any symptoms, and on each occasion, carrying transmittable virus round with them to endanger everyone else.