My theory is those countries volunteering to be a petri dish might end up doing the world a favour. Some delta variant hopefully mutate to something less deadly.
It has to be less deadly, more virulent,
and confer immunity against other strains.
The reason why Delta is displacing other strains is not because they mutated into Delta. It is because Delta is out-competing them. The other strains are being beat back by NPI and vaccination and the people they try to infect already being infected by Delta.
Non-Delta level strains are completely crippled by the vaccine; almost nobody develops symptoms and they spread it really poorly. Delta is only slowed down by the vaccines.
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Hockey league in province for elderly had a massive outbreak including at least one death. Everyone was vaccinated.
Heavy breathing in cold arena without external air exchange and filtering. It wasn't just people who played against each other, the entire league caught it.
There is currently a battle in the infection control branch of medicine.
On one hand, there is the droplet and fomite side. These are the people who say "stay 2 m apart", "use plexiglass barriers", "wash hands and surfaces frequently".
On the other, aerosol. These are the people who say "interact outdoors", "be well ventilated", "wear masks, n95 or medical grade ideally", "install air filters".
The fomite side has the advantage of being easier to do. Fixing ventilation problems is hard in legacy buildings. The problem is that it looks like they are wrong.
The belief that respiratory illness spreads via ballistic droplets and fomites, and only rarely via airborn transmission, looks like a 50+ year old error caused by the fact that TB requires 5 nm particles to reach the bottom of your lungs and infect people. Particles larger than 5 nm get caught in the upper respiratory tract.
And while the work showed that particles up to 100 nm where reasonably well airborn, that 5 nm limit -- which tells you what you need to filter out to stop TB from spreading -- got picked up in the literature, and it became dogma that "airborn transmission occurs with 5 nm and under particles", instead of "airborn transmission of TB occurs with 5 nm and under particles".
Covid 19 5 - 100 nm particles (of saliva) can stay airborn for quite a long time, and it appears that they are the primary method of transmission. To prevent transmission, you need to ventilate or filter the particles out of the air, and wear masks to keep them out of people's upper respiratory tract. Have a room without air exchange, and the infectious particles will float right around a plexiglass shield, and far further than 2 m.
Buy HEPA filter systems. Or make your own; there are some really cool custom builds that involve a box fan, some tubing, and cheap filter material.