Japan: reported covid cases have plummeted by 98% in the last eight weeks.
No lockdowns, no changes in behavior, no new mandates, or mask requirements.
What could explain this sudden drop to the lowest case numbers since October 2020?
Apparently, experts and the media are baffled by Japan's "puzzling" and 'mysterious" success:
Could the answer be vaccines? Japan has now fully vaccinated 67% of their population, with 57% now at the magic 2+ weeks after second shot.
Compared to, say, the UK and Singapore, Japan has fewer people fully protected but more people recently protected.
Given the recent trends in the UK and Singapore, it is obvious that Japan's vaccine coverage can not be credited with plummeting case rates - unless VE waning is much more dramatic than we are being told.
In 2020, cases in Japan peaked in August and then fell through mid-October, the exact same pattern observed this year, so some portion of the decline must be due to seasonal forcing factors.
Another factor: a recently published study indicates that only about 1 in 500 covid infections were being detected in Japan due to low levels of testing of the asymptomatic - and the vast majority of Japanese infections appear to be asymptomatic.
ncbi.nlm.nih.gov/pmc/articles/P…
A seroprevelance survey of asymptomatic retail workers in Tokyo indicated that nearly 50% developed antibodies over the course of summer 2020.
It may be that Japan's plummeted cases are due primarily to achieving herd immunity through natural infection.
medrxiv.org/content/10.110…
The flu has not yet returned to Japan; perhaps due to the fact that Japan is an island with strict border controls.
[Note how masks are often credited with eliminating the flu - but they never "worked" in Japan until 2020.]
If Japan really has achieved herd immunity via natural infection, they have managed to pay a remarkably low toll compared to Europe and the Americas.
Like the rest of Asia, especially East Asia, Japan has had very little mortality despite wide-spread infection:
In fact, Japan has had no excess mortality, at all, since the beginning of the pandemic - again, this comes despite wide-spread infection.
Japan's success wasn't in preventing infection, but rather in avoiding serious illness & death despite widespread infection.
Given experience elsewhere, this success is not likely attributable to their recent vaccinations.
The real "secret": population health & prior immunity.
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