As is obvious to everyone, the delta variant is surging. Given its infectiousness, this is hardly surprising; as covid-19 adapted to humans, variants became successively better at infecting people, and delta is more than three times as contagious as it was spreading last year. And delta is not the last variant we will see.
This raises many questions, and the three most important are: Will it become more virulent — causing more serious disease and death? Will the virus escape the protection natural immunity and vaccines now afford? And, if the answer to either of the first two questions is yes, how can we respond?
Right now, the best we can do is make educated guesses. There’s no solid information yet on delta’s virulence, although it seems more dangerous. It wreaked havoc in India, but it’s difficult to know how much of the death toll can be attributed to increased virulence and how much to an overwhelmed health-care system. Anecdotal accounts here also speak to increased virulence, including in younger adults. We also know that delta produces about 1,200 times the viral load of the original virus — and viral load correlates with severity and death. That fact is not comforting.
Neither is history. All five influenza pandemics we have details about developed more virulent variants before settling down. The pandemic beginning in 1889 was more than twice
— source washingtonpost.com | John M. Barry | Jul 26, 2021