The Omicron variant

+1 It's certainly looking a lot less deadly, but as you say we're not dealing with a blank slate here. Vaccines, previous exposure and the horridly termed "dry tinder" effect where the weakest people in a demographic die off in the first wave, so there are fewer very vulnerable people second and third time out can skew the numbers. The numbers themselves can hide things too. In the sense that thankfully this is not a particularly deadly virus unless you're in the very vulnerable groups and even there you'd still be very unlucky to die from this pox even pre vaccines. So people today reckoning they've had it and it was like a bad headcold doesn't tell us much, even if the person is unvaccinated. For over 99% of the overall population before vaccines and with previous variants it also could have been described as a "bad headcold". Unless you were in that 1% where it most certainly wasn't.

Even so the hard facts around vaccines are in. When half of ICU patients are unvaccinated and the wider adult population is well over 90% vaccinated and the age profile of those patients is dropping when the age profile before vaccines was going very much in the other direction it's pretty clear the vaccines worked extremely well against serious illness and death.

I see your point Dom. It's more my point that this constantly repeated mantra of "viruses get more infectious and less deadly over time" that I have problems with.

I suppose for clarity I would say that the evolutionary fitness of a virus is what counts and transmission/reproduction is numero uno and what is selected for. Lethality is a coin toss. While some may mutate into less lethality as a byproduct of increased transmission(or pure luck). Omicron seems to be one such case. It became more infectious because it hits the upper respiratory system and the body can get to fighting it before it gets and deeper and cause more serious illness. However they might just as easily mutate for increased transmission and more lethality as a byproduct, or become more transmissable and stay just as lethal. Where there could be selective pressure on a virus to mutate for less lethality would be if the host got so sick and died before spreading the virus, then the variant that let the host live for longer and spread more would become the winner.

That's before we get to the immune system and how a virus runs through a population. In a "virgin" population the virus spreads and serious illness and death ramp up. The recovered and the dead(and latterly the vaccinated) are resistant to that variant so if another wave occurs that original population suffer far less, so it looks like the virus got less lethal over time.

Again if we look at history and viruses that affect humans. Some have been around for thousands of years and didn't change in lethality. Influenza is with us every year and in most years it's mild, save for a minority. When it has mutated in the past it's far more likely to have mutated to be worse.

But take covid 19. Alpha was a major worry, but the second wave Delta was more infectious and as deadly if not more so in the population(unvaccinated), Omicron is more infectious again and appears to be less deadly. Same virus, different strains, getting progressively more infectious, but when it first became more infectious it also got more deadly. Another variant could become more deadly with the same infectiousness. However Omicron being so infectious and in majority vaccinated populations some sort of "herd immunity" is looking good, so unless a covid comes along that evades immunity we should be looking very good.