1) Despite the fact most people wear face coverings in public places in Japan and South Korea, both countries are now experiencing resurgences in #COVID cases and hospitalizations. In this thread, I will try to explain what may be driving the 8th #pandemic waves in those nations.

2) First, the facts. There's no doubt both Japan and South Korea are now at the start of an 8th wave in the #pandemic. Please see the chart below by Our World in Data revealing the uptick in cases per million population, with South Korea's trend line a bit higher than Japan's.

3) Japan and South Korea are also observing resurgences in #COVID hospitalizations, with Japan's trend line markedly higher than South Korea's. As you can see below, hospitalizations are still much more elevated in Canada, but they seem to be trending down or at least plateauing.

4) At present, it's the BA.5 offshoot of the #Omicron variant of concern that is driving the resurgences in Japan and South Korea, although BQ.1 and XBB — both with marked immune-evasive properties — are beginning to catch up. Will those subvariants prolong the 8th waves there?

5) It would be overly-simplistic to suggest that mask-wearing in Japan and South Korea is not making a difference. It's likely that without widespread use of face coverings, the #COVID contagion would be even higher in those two nations. So what is to blame for their resurgences?

6) In Japan, one theory is the 8th wave follows the government's decision last month to end coronavirus border controls and launch a domestic travel subsidy program to spur local tourism. The northernmost island of Hokkaido, a popular tourist destination, is posting record cases.

7) In South Korea, authorities have expressed concern about what the Yonhap News Agency is reporting is a "low inoculation rate of a booster dose of the BA.4/BA.5-adapted bivalent vaccine during wintertime, which could accelerate the pace of the virus wave." Please see below.