People don't get sick from temperature changes. I'm in Canada and in winter go from a 25C house to -25C outside. We'd all be dead of that were true. Late winter early spring I am outside in a t-shirt shovelling show in -7C.
But you were used to it from being raised in such a climate. Those who are not (or lived in air conditioned houses all the time) can get serious trouble adopting.
Edit: I know people who like walking bare foot, but cannot really, because they had floor heating all the time as a child. So now they get sick really fast, if their feet gets a little bit cold. I had no floor heating and I can walk barefeet in the snow (for some time. And today I like floor heating in the bathroom). My point is, be conscious how you raise your kids and live yourself. Don't make it too comfortable ..
Edit2: you can train it even in the shower: switch from cold to hot a couple of times, as intense as you can manage with conscious breathing. That helps me, if I don't overdo it.
Since people is not prepared correctly, the number of people I see coughing in the subway is definitely higher.
Not extreme deaths like covid, but impairs people more than usual.
Also my daughter is bringing more stuff from the school that are not learning and knowledge, but viruses of all kinds.
Also kind of funny to read such hero experiences of someone stepping out for a short amount of time of his controlled climate, pure luxury, enjoy but stay calm!
I am from South America and moved to Canada and find Canadians are most of the time either inside their cars or indoors, both places they can control the temperature
Heaters are not common at all in South America, nor are thermostats. Air conditioners are somewhat but I wouldn’t say a majority of the population has them. And a smaller percentage of the populations owns a vehicle because it’s expensive for them.