A friend just forwarded me a link to a Nature article describing and quantifying pre-symptomatic transmission of the novel coronavirus:
www.nature.com/…
Interestingly, I had just finished reading an article in Science News (from my daily Science News update) that basically translates and compresses the Nature article for public consumption:
The very condensed summary: people are most contagious when they are pre-symptomatic; the production of infectious viruses peaks before symptoms first show. For a good overview, read the Science News article. To dig into the weeds, the Nature article has far more detail, plus graphs.
We've known from near the beginning that people are contagious when they're pre-symptomatic, but that was simply qualitative. This study makes it quantitative, and the numbers are bad. It seals the case for universal testing, contact tracing, and isolation as the only way to contain the pandemic, shoots elephant-sized holes in Trump's idiot rush to "reopen", and brings us back to the need for universal vaccination as the only way we can prevent future outbreaks.
We have long-time experience with universal vaccination - smallpox, measles, and polio, primarily, and yellow fever and other diseases in specific parts of the world. And they have been spectacularly effective. But today we're stuck with a completely insane anti-vaccination movement that has paradoxically immunized itself to facts. This is not going to be easy.