March 23, 2020: Japan's Curious Lack of Coronavirus Cases
Good morning,
First, if you are healthy, consider donating blood. From The Red Cross:
Right now, American Red Cross faces a severe blood shortage due to an unprecedented number of blood drive cancellations during this coronavirus outbreak. Healthy individuals are needed to donate now to help patients counting on lifesaving blood, platelets or AB Elite plasma.
I’ve heard that hospitals are changing their thresholds for transfusion because of reduced supply—not good.
On to the update.
Japan's Curious Lack of Coronavirus Cases
The conventional wisdom is that China and the rest of Asia “won” the battle on coronavirus because of severe lockdowns and widespread testing. But what if that’s not the whole story? There are certainly some inconsistencies in the approach between the various Asian countries.
From Bloomberg:
Unlike China’s draconian isolation measures, the mass quarantine in much of Europe and big U.S. cities ordering people to shelter in place, Japan has imposed no lockdown. While there have been disruptions caused by school closures, life continues as normal for much of the population. Tokyo rush hour trains are still packed and restaurants remain open.
The looming question is whether Japan has dodged a bullet or is about to be hit. The government contends it has been aggressive in identifying clusters and containing the spread, which makes its overall and per capita number for infections among the lowest among developed economies. Critics argue Japan has been lax in testing, perhaps looking to keep the infection numbers low as it’s set to host the Olympics in Tokyo in July.
Japan has ramped up its capacity but has tested only around 5% the number of people as in neighboring South Korea, despite a larger population.
So here is Japan, without lockdowns and without widespread testing, but with relatively mild case numbers and relatively few deaths. What’s going on?
What I’m about to suggest is pure speculation at this point, but maybe together we can find confirming and disconfirming evidence.
What if the culture of wearing masks is actually having a huge effect on the spread of coronavirus in Asia?
From this medRxiv paper:
Asymptomatic cases were estimated to account for 34.6% of the virus positive cases onboard the Princess Cruise ship.
Consistent with these studies, our analyses and extensive simulations also indicated an ascertainment rate of 14%-41% in Wuhan (Table S2). Increasing evidence also suggested that the asymptomatic and presymptomatic cases can be infectious to the susceptible population, imposing a substantial challenge to the epidemic control.
In other words, we think many people are walking around spreading COVID-19 without even knowing they have it. Maybe someone sneezes for an entirely unrelated reason, and yet that sneeze spreads the virus.
And this is where masks come in. Imagine that 50% of the population wears a mask (presumably because they are worried about getting the virus). Even if those masks are ineffective protection for healthy people, they could still be extremely effective at preventing an asymptomatic carrier from spreading. Coughs stay in the mask, runny noses aren’t wiped with hands, you get the picture. And a 50% reduction in viral spread is a really big deal.
If this is the case, I would expect the social isolation measures in Italy and the US to be less effective than equivalent measures in Asia. And we may also see reduced transmission rates in communities that have widespread mask use, like in Asian enclaves of US cities. For one example of such an enclave, in SF’s Sunset district I saw about 50% of people on the street wearing masks yesterday, while masks are vanishingly rare in the rest of the city. The Asian dry-goods store even had masks for sale!
One last note, please don’t let these comments cause you to hoard masks. We’re still collectively in major trouble if health care providers don’t have the masks they need.
WFH Setup of the Day
“Sheltering in place” can mean on the roof with panoramic city views, right? And look at that distancing!
Thanks for reading. This is going to be a challenging week, take care of yourselves!
See you tomorrow,
Andrew