[m4rtink]

The percentage rising could be a big indicator of things starting to go bad. Here in Czech Republic the percentage was around 4 percent for a long time and things were looking good - tens maybe a hundred cases a day, couple hundred dead. Then in late summer/early autumn it started to rise, crossed 10, then 20 and went up to more tan 30. At that time there were 15000 next cases detected daily, hospitals under strain and daily deaths above hundred.

Preatty drastic measures have been implemented (non essential shops closed, nigtly curfew, restaurants takeout only, all schools closed, mandatory masks in all public spaces) and the numbers are going down to about 2000 per day most recently.

The measures seem to have been effective, but a a cost of about 6000 more dead - and more can be expected due to the inherent delay.

So for that reason, percentage of positive tests really should be watched carefully.