It's now past two years since SARS-CoV-2 (Covid-19) spread beyond China and became a pandemic.

From the outset, I've covered aspects of the pandemic on this website, beginning with Love in the time of Coronavirus back in March 2020, so the passing of the pandemic's second birthday seemed an appropriate time to review what we've learnt.

The positive news is that: Covid-19 has been far less deadly than the 1918-20 "Spanish Influenza' pandemic. 

This relative success in limiting the number of deaths this time round is entirely due to modern science.

Although historians disagree over the numbers, all agree that the Spanish Influenza pandemic killed a great number. The lowest estimate is 17 million worldwide, while another puts it at between 24.7 and 39.3 million. Most, including the National Museum of Australia and Wikipedia, tell us that over 50 million people died worldwide. This was when the population of the world was 1.9 billion, less than a quarter of that it is today. However, most historians do agree that that virus did not originate in Spain but first crossed to a human in the United States originally from a waterbird (it was H1N1), then possibly, via a pig. The earliest documented case was March 1918 in Kansas. It was carried into the trenches of the Great War by one or more American 'Doughboys', from whence it spread across the world as the war ended.  As Dorothy opined: 'Toto, I've a feeling we're not in Kansas anymore.'

In the early 20th century, vaccine development was by trial and error. Although bacteria could be seen using a powerful, optical-microscope, virions (virus particles) were invisible and could only be inferred to exist, like atoms 50 years ago. As a result, attempts to produce a vaccine in the 1920's targeted suspicious bacteria and were totally ineffective against the influenza, as were many attempted and folk-treatments - perhaps injecting disinfectant?  No, no one would be that stupid!

Masks and social distancing provided the only effective mitigation until natural (herd) immunity stopped the spread.

Unlike that, most deadly, to date, of all viruses, this virus certainly originated in China.