The reality is, most of the cases of COVID-19 coronavirus infection have been diagnosed without confirmation by laboratory testing.  And so, doctors end up finding what they are looking for – – COVID-19.  The singular mind-set of modern medicine continues to be practiced today.  COVID-19 fits a script that was created prior to this current epidemic.  That is because they want to develop a single-component vaccine and inoculate the entire planet at one time (the dream of a billionaire philanthropist).  So, better get sick to make his dream come true (NOT!).  Somehow, vaccine makers were reportedly making a COVID-19 coronavirus vaccine long before the first outbreak in China.

Similarly, most virologists collectively believe the Spanish flu of 1918 was caused by an influenza virus, with some level of certainty, maybe H5N1.

By the way, the US had a population of 103 million at the time and an estimated 550,000 Americans died of the Spanish flu, which is ~ a 0.5% death rate (half of one percent).  Today the US has a population hovering around 325 million and a 0.5% death rate would result in 1,625,000 deaths.  But let's recall, 1918 was an era before chlorinated water (eradicated cholera, typhoid and dysentery), and before nutrient-fortified foods.  But we also have more older adults (12+ million over age 80), the primary at-risk group for COVID-19 mortality.