It's a guess, but a plausible one. We know the virus is destroyed quickly by UV light, which is stronger in summer. People spend more time outside in summer, an

It's a guess, but a plausible one. We know the virus is destroyed quickly by UV light, which is stronger in summer. People spend more time outside in summer, and we know transmission is reduced outside. Other respiratory viruses spread poorly in summer. It's hard to compare with Brazil, because the stats coming out of there are poor and they're making less attempt at controlling the virus compared to almost any other country.