Japan will face rapid acceleration of covid-19 in April, leading to a public health crisis#
The governmental and media consensus is that Japan is weathering
covid-19 well. This consensus is wrong. Japan's true count of covid-19
cases is understated. It may be understated by a factor of 5X or more.
Japan is likely seeing transmission rates similar to that experienced in
peer nations, not the rates implied by the published infection counts.
The cluster containment strategy has already failed. Japan is not
presently materially intervening at a social level. Accordingly, Japan
will face a national-scale public health crisis within a month, absent
immediate and aggressive policy interventions.
Update as of the afternoon of March 26th: The government's panel of
experts has said that infections are highly likely to be
We concur with that assessment. We are presently unaware of published
official projections consistent with the projections discussed in this
white paper, with the exception of the one from Osaka, discussed below.
As of March 24th at 3 PM JST, Japan has reported 1,135 cases (excluding
those aboard the Diamond Princess, charter flights, and officers
attending to them), of which 859 are active, 54 are critical, and 41
have resulted in the death of the patient.
The government has messaged a wait-and-see attitude (検討する) with
respect to proactive containment measures outside of diagnosed clusters.
There do not exist official reports of material community spread outside
of surveilled clusters.
The current figure is likely a massive undercount. If it is an
undercount, it is highly unlikely that Japan's official position that it
is correctly identifying most clusters quickly and preventing spread
from them is accurate. As Japan's strategy is built around aggressive
treatment and containment of clusters, breakout from clusters is an
emergency. It threatens rapid uncontrolled increase in infections, which
will cause a breakdown in care (which Japan refers to as an "overshoot")
when the hospital system is overwhelmed, leading to a sharp increase in
We have statistical evidence suggesting that containment failure and
community spread has already happened.
Reasons to doubt the consensus
Japan is undercounting asymptomatic individuals, who can spread the
Japan has had a public policy of refusing to test asymptomatic
individuals except for those having a deep degree of direct contact with
an infected individual (濃厚接触者), and
only tested individuals with contact if they also had a fever or
Accordingly, we should expect this testing policy to underdetect
asymptomatic infections, and indeed we have evidence suggestive of this.
The Ministry of Health, Labor, and Welfare has released national
statistics for patients who were diagnosed with covid-19 as a result of
a PCR test on 3/10, 3/11, 3/12, 3/13, 3/14, and 3/23. These statistics
include breakdowns by whether a patient was symptomatic when diagnosed
or asymptomatic. Asymptomatic patients are consistently roughly 10% of
all diagnoses (ranging from a low of 10.24% to a high of 11.29%). This
is far less than we should expect for covid-19.
Japan's experience on the Diamond Princess is instructive of what we
should see if everyone in a population were extensively tested. All
passengers were tested, repeatedly, before being allowed to disembark.
The National Institute of Infectious Diseases
that 48% of infected patients were asymptomatic at the time of sample
If the true rate of asymptomatic infection is higher than the observed
rate of asymptomatic infection, and we make the generous assumption that
100% of symptomatic patients are successfully identified, then there
must be a large population of asymptomatic infectious carriers who are
not counted in official statistics. They are not subject, unless they
are in direct contact with an infected individual, to any restrictions,
monitoring, contact tracing, or medical care. They do not consider
themselves ill. They do not know they are capable of spreading the
disease to others.
To estimate how many asymptomatic infections are being missed, we divide
the number of cases of diagnosed symptomatic infections by the estimate
of the true rate of symptomatic infections (which is lower than the
observed rate). This gives us an estimate for the true number of
infections. The difference between this estimate and the current
official count are estimated asymptomatic infections which have not been
E.g. Using the March 22nd Ministry of Health, Labor, and Welfare data:
907 / (1 - 0.48) =\~ 1,750 true infections
This is approximately 70% higher than the number of detected infections
on March 22nd.
This also magnifies the impact of any underdetection or
misclassification of symptomatic infections. For every symptomatic
infection missed by the current regime, we are also likely missing an
Iceland's chief epidemiologist, who has testing capacity to cover almost
the entire population of Iceland,
that 50% of their infections are asymptomatic. If this ratio held in
Japan, it would suggest Japan has \~80% more infections than are
A pre-print from the Journal of Infectious
by a Japan-based team, uses Japanese citizens' experience to calculate
the asymptomatic rate. Japan evacuated citizens from Wuhan and
exhaustively tested them on returning to the country, catching more
asymptomatic infections than the testing strategy Japan generally
employs. The researchers arrive at an asymptomatic ratio of 30.8%. This
suggests that Japan has \~30% more domestic cases than are currently
reported, again assuming perfect identification of all symptomatic
A pre-print from
estimates the true asymptomatic rate on the Diamond Princess at 17.9%,
using more sophisticated modeling than the calculation we performed
above. This again implies that Japan is undercounting cases, though not
as dramatically as either of the above estimates would suggest.
Japan's reported deaths are likely caused by a larger infection count
than it is reporting.
A pre-print from the Center for Mathematical Modeling of Infections
diseases, Using a delay-adjusted case fatality ratio to estimate
attempts to calculate the true number of cases by reasoning from
predicted case fatality ratios (CFRs). Each death observed in a country
at a particular date corresponds to, probabilistically, approximately 1
/ CFR infections occurring over an interval of several days prior to the
observed date of death.
This research estimates Japan's detection rate to be between 15% and
35%. Accordingly, Japan is undercounting cases by a factor of
approximately 3X to 6X.
Countries that test people who have been in Japan find more infections
than Japan does.
four coronavirus cases to individuals who had just been in Japan.
To be conservative we'll assume three of these infections, not four, are
Japan-related, as we have no knowledge of travel of the Japanese
Singaporean resident. Due to the usual course of the disease,
Singaporean health authorities concluded it is likely that these
individuals contracted it while they were in Japan.
Singapore's sole airport keeps statistics of inbound passengers by
The average passengers per month over February and March in 2018 and
2019 (most recent data available) was 128,000. Over a roughly 2 week
period, we would expect approximately 64,000 passengers to fly from
Japan to Singapore. 3 infections in that population is a rate of
approximately 47 basis points, which is 5X the 9 basis points rate of
infection in Japan. If one believes the government, the rate with
surveilled clusters backed out be a tiny fraction of 9 basis points.
This implies either that tourists are exceptionally unlucky at stumbling
into exactly the wrong music shows or medical facilities or, in the
alternative, that there is unsurveilled community transmission bringing
Japan's true case count to many, many times the admitted count.
Why does Singapore's airport detect more infections in people who have
been in Japan than Japan detects in people who have been in Japan? It is
likely because Singapore's airport tests aggressively and Japanese
medical offices do not.
If we believe it is credible that tourists passing through Japan
encounter clusters at the same rate as people who stay in Japan, which
is unlikely, this implies the official count is understated by 5X.
If tourists are only getting affected by community transmission, this
implies the official count is understated by 25X or more.
Where are the missing asymptomatic cases?
Japan's official position, as stated at the March 19th Panel of Experts
as well as elsewhere, is that Japan is focusing on a cluster-based
Japan's testing capacity is underused, as a matter of policy. Local
health offices control access to testing. The Japanese Medical
Association has alleged, as
by NHK, that doctors were denied permission to test more than 290
patients where the doctors felt the tests were medically necessary.
Testing capacity (where it is used) is allocated to symptomatic
individuals (preferentially to those with contact with diagnosed
individuals or travel histories to epidemic-afflicted regions) and
people with high degrees of contact with diagnosed individuals.
The inference is thus that missing asymptomatic cases are outside of
identified clusters, in the general population, potentially causing
The above statistics are strong circumstantial evidence of a very
material number of non-clustered cases, which risk community
transmission. We have direct evidence of community transmission as well:
local Japanese governments are beginning to report it.
Japan's containment strategy is failing
Japan official sources at the prefectural level are beginning to
acknowledge that containment efforts locally are failing.
For example, Osaka Prefecture and Hyogo Prefecture are currently
epicenters of the outbreak in Japan. In a
which Gov. Yoshimura showed on TV on March
and is dated as having been prepared on March 16th, experts acknowledged
that cluster containment was failing, as evidenced by new infections
without a detected link to an existing cluster (community transmission).
Quote: "It is believed that infections without surveilled chain to a
cluster continue to increase and that therefore a rapid increase in
infections has already begun."
Aichi Prefecture (Nagoya) has reported and unreported shortages of
hospital beds suitable for high-grade infectious disease treatment (like
covid-19) and generally. Asahi Shinbun
on March 11th that over half of their capacity (161 beds) was already
used. It was not generally reported at that time that they had begun
triage. According to the prefecture on the
are currently 103 hospitalized patients. 27 of them have not been tied
to either of the prefecture's known clusters. Nagoya is likely in a
state of uncontrolled outbreak and medical care will likely suffer
there, within days.
As of March 19th, the government's declared containment strategy
remained rapid cluster identification, surging medical attention on
diagnosed patients, and asking for voluntary changes in behavior from
The cluster containment strategy has failed. Medical care in
epicenters will be modified to adjust to a worsening reality, within
days. The voluntary behavioral changes have been modest. They have been
insufficient to maintain viability of the first two prongs of the
strategy. We should not expect this level of behavioral change to
prevent the situation from worsening.
Travel within Japan is routine, central to commerce and leisure, and
almost entirely unimpeded. In normal times, there are 500,000 passengers
on the Tokkaido Shinkansen between Tokyo and Osaka per day. In
February, usage of it was down by only
per the Nikkei Shinbun. An outbreak in Osaka, Nagoya, Tokyo, or similar
major metropolitan areas is extremely likely to metastasize throughout
Japan absent aggressive restrictions on movement, especially public
transportation. This outbreak and subsequent spread has almost
certainly already happened.
Japan is not materially preparing at a societal level
It has been widely reported domestically and internationally that the
Japanese populace is extremely cooperative, hygiene-focused, and has a
culture of donning masks to prevent infecting others and/or as a
precaution against seasonal hay fever. This is not a strategy. We
are already observing breakout infections. We should assume, until we
see persuasive evidence otherwise, that infection spread in Japan
resembles that of peer nations taking minimal precautions. This requires
us to believe the evidence of our eyes and our instruments, not the
evidence of our hopes.
The concrete action taken by Japan was suspending substantially all
schooling nationwide on February 27th, two weeks before the spring
holiday. Japan has discouraged large events, such as the live music
event which generated Osaka's first surveilled cluster. Aside from these
measures, and individual citizens and organizations adopting very modest
levels of caution, it is business as usual.
By casual observation, mask wearing in central Tokyo is below 30%,
including in well-attended outdoor events such as hanami (cherry blossom
watching) parties. Reporters have not observed social distancing or
universal mask use at press conferences about the epidemic.
The government has recently released
that recommends masks most strongly in environments which are enclosed,
with high density of people, with conversations or vocalization. This
recommendation has not succeeded in closing bars or restaurants, and
appears to carve out mass transit and hanami, which are economically and
socially significant. It is uncertain the degree to which this carveout
is warranted by medical science.
Japan will face a national health crisis within a month
Osaka forecasts a likelihood of 3,374 infections (including 227 severe
cases) before April 3rd, compounding a rate of more than 6X per week.
(This estimate was included in the document shared by the governor.) New
York, with aggressive measures to slow the spread of disease, shows
compounding of only approximately 2X per week.
If government infection counts were accurate, but containment has
failed, and we use optimistic doubling rates observed in peer nations
taking aggressive measures, we would expect to see on the order of 3,000
cases, including more than 200 severe cases, in each of Nagoya, Osaka,
Tokyo by the end of April.
If we do not use peer nations' experience for doubling rates, and
instead rely upon the estimates of the cluster identification working
group who prepared the report for Osaka, and we do not implement
aggressive measures to slow the spread of disease, we could see more
than ten times to one hundred times that number.
These scenarios both will likely lead to a breakdown in provision of
care, which Japan refers to as an "overshoot." The experience of peer
nations suggests that that would lead to patients dying in the wake of
care being impeded, at a sharply increased rate, and in patients of
other conditions dying as other forms of medical care are also impeded.
Tokyo on March 23rd
that it had 118 beds appropriate to safely treat high-level infectious
disease patients, with plans of adding 700 beds for severely affected
patients and 3,300 for those with moderate symptoms.
Additionally, the bottleneck is likely not beds but rather skilled
medical personnel; Japan faces an ongoing shortage of them at the best
of times. Japan is likely unable to surge them from unaffected regions
to epicenters. Many medical personnel already live in epicenters. Those
that don't will be equally needed to treat the likely coming
uncontrolled outbreaks at home.
The above scenarios apply estimates of growth rates to currently
reported numbers of infections. The currently reported numbers are
very likely not accurate. They are, as described above, a gross
undercount. Reality is very likely worse than current guidance from
official sources, and therefore the April we encounter will be worse
than observers who rely on those numbers suppose.
We project a true count of over 500,000 infections, including more
than 5,000 severe cases, and a breakdown in provision of care
("overshoot") in Nagoya, Osaka, and Tokyo, before the end of April.
There will almost certainly be other breakdowns nationally. April is
extremely unlikely to be the worst month. Accordingly, by the end of
April, we will have an undeniable national public health emergency.
Japan must act now
As of March 19th, the government's declared policy was that it would
wait-and-see about infection spread and consider asking the public to
engage in voluntary (自粛) social distancing in regions with outbreaks.
"However, a Japanese official who gave an off-the-record briefing to
Asia Times suggested that a "don't ask, don't tell" strategy, based on
minimal testing and buttressed by information massage, has been quietly
Governor Koike of Tokyo floated a trial balloon on March 23rd
contemplating the possible lockdown of Tokyo if there were an outbreak
in Tokyo, while emphasizing that a lockdown should be avoided at all
costs. Governor Koike announced, on March 25th, a voluntary stay-at-home
order for Tokyo starting on March 28th.
Many cities in peer nations have experienced what we will soon
experience. We do not believe they would advise us to delay our
As a nation, we believe we are in a peaceful spring.
We are not.
We will, within the month of April, confront a crisis worse than any
since the war. We must take immediate, concerted, aggressive policy
steps in light of this reality.