Weekly COVID-19 in Japan aggregated stats update. In sum, another frustrating week but it could have been much worse given many countries experienced doubling rates of between 3-6 days in key indicators at critical points.

First, testing indicators. There was a much smaller increase in the number of new tests conducted compared to the previous week, although still a much quicker pace than even at the start of the month. Cumulatively, a tripling of tested individuals since the beginning of April.

However, the number of new positive cases detected increased even faster than the number of new tests conducted—although there was a less steep week-on-week jump compared to the previous two weeks.

Nevertheless, there was a significant increase in the detection rate compared to prior weeks (percentage of tests that picked up new positive COVID-19 cases).

Is this increased sensitivity because things were objectively worse around 1-2 weeks ago? Leaving winter behind making potential COVID-19 cases with flu/cold-like symptoms easier to spot? Both? Something else? Doesn't seem we are getting close to saturation point yet in testing

The number of deceased again increased week-on-week, although, thankfully not doubling. It still remains orders of magnitude less in raw and per capita terms than many other countries—for now at least.

A possible key indicator of further deterioration in this number is how many current or 'active' serious cases requiring ICU admission and/or respiratory assistance there are in Japan. Serious active cases were +71 (net) this week, coming to 176, a sizable jump on last week (+39)

The linkage between serious active cases and deaths is unsurprisingly tight (R²=0.96), so even if the state of emergency helps level things out a little in terms of new cases, it is likely that the number of deceased cases will get worse before it gets better.

New discharged cases did see an expected bump—although representing an even smaller percentage of new cases than before.

Thus, active cases grew significantly on the previous week to close to 7000 nationally. Another week-on-week increase of that magnitude—close to doubling in the aggregate—may well herald the dreaded 'overshoot' of medical capacity, despite recent local efforts to enhance it.

In terms of aggregate trends, clearly active cases are seeing the steepest increase (see below). Whether the numbers of serious & deceased cases will follow it as a function of newly detected cases (& frankly, increased testing), will be of keen interest over the rest of April.