My understanding of COVID-19

Human cells that are in contact with the outside world include the gut, airways, and skin. These get replaced regularly because they are subject to damage and disease.

 Viruses infecting these externally accessible cells don't want to get into the blood stream and affect internal organs. They want people to be well enough to move around and infect other people. So we see that there are a lot of respiratory and throat viruses that cause mild disease, and this includes various coronaviruses.

The exceptions are diseases that have only recently made the jump from other species. Initially they can be quite dangerous. New variants will be more successful if they are milder. That's what we've seen with covid-19. Indeed, it doesn't seem unlikely that covid-19 will eventually settle down to be just another "cold".

When covid first hit, vaccination development started, and soon there was talk of the need to vaccinate the whole world. That didn't happen. The virus running unchecked in many poorer places led to variants, and concern was expressed that they might be more dangerous. But, as epidemiologists must have suspected, it was milder variants that won the day. One cannot help but wonder if this policy of benign neglect in other poorer countries was deliberate, or just, as it seemed to be, laziness. Sweden also let the disease run more than most richer places. Were they doing their bit to encourage milder variants?

Influenza never makes this change to milder variants. I presume this is because it is always making the jump from birds, so we're always dealing with new variants.

An interesting feature of the pandemic where I live was that there was initially denial that it spread through the air. So there was no recommendation to wear masks, though many did. At that time I tried to buy masks, but they were all sold out. Then the story changed and it was admitted that there was aerial transmission, and masks were recommended. And bingo, suddenly they were available everywhere. Was this a coincidence? I don't think so. They didn't want to even recommend masks when you couldn't get them. Soon after that they were required in many situations.

Transmission has always been low in outdoor settings with sunshine. So many of the bans that happened were undesirable. People would have been safer if they got some vitamin-D in the sun. I also think that we can provide more UV in indoor settings. A big UV lamp might be dangerous, but we can now provide strip lighting with small amounts of UV coming from multiple places and illuminating everywhere better than central lights. Unfortunately the anti-UV lobby has a big hold on the public imagination.