When astronomers use some of the most powerful telescopes in the world (and orbiting it) to peer into the heavens and see the stars what they are really doing is taking a trip into the past. The light from many of the stellar bodies that scientists focus on today has been coursing through the cosmos for millions, if not billions of years. So what the astronomers see today is light that left those stars, galaxies, quasars, pulsars, etc. a long, LONG time ago, and often from a galaxy far far away.
In a very similar way, the numbers that epidemiologists use to describe an active epidemic or pandemic are not reflective of the current situation, but rather reflect the past–how far into the past depends on the virus or disease in question.
For the current SARS-CoV-2 virus that causes the COVID-19 disease the incubation for the virus seems to be incredibly variable. The average incubation period (time from infection to onset of first symptoms) is about 2-5 days, which isn’t that uncommon as these things go. What is extraordinary in the extreme is the fact that some cases have been documented that have developed symptoms after 14-24 days, possibly longer. That makes this virus INCREDIBLY difficult to contain and control. I should know this, it’s one of the traits my sources at the CDC and WHO said to pay especially close attention to in my research for my latest book.
What that means for the “current” situation with COVID-19 though is that whatever current case counts reflect, those number do not indicate the current number of people who have been infected by the virus. They actually show the number of people who were exposed to it at the very lest 2-14 days ago. And, it gets a little worse (a common theme with this virus). Not only is there a long delay between acquisition of the virus and the onset of symptoms, but once symptoms start it can take 2-4 weeks before they get serious enough to require medical interventions.
That means a person could go as much as 4 weeks from the time they were infected until they got sick enough to go to the doctor, get tested negative for flu, and then, if they and we are VERY lucky, get tested for COVID-19. That is a an incredibly long time as these things go, and it makes the job of tracking and containing the spread of this disease a monumental task that would be incredibly difficult even if testing numbers were where they should be—and they’re not, nowhere close.
So keep in mind that when you see the “confirmed” case counts in the news and media this is NOT the current situation with COVID-19. It’s the situation anywhere from 2-28 days ago. And there’s a good chance that, like a star whose light has been travelling through the cosmos for billions of years, the situation is VERY different now than it was then.