Michael Mina, MD, PhD, assistant professor of epidemiology at Harvard T. H. Chan School of Public Health, assistant professor in immunology and infectious diseases at Harvard T. H. Chan School of Public Health, tweets "In US Perhaps 30+ MILLION have had #COVID19 virus In NYC, 15% of pregnancies had antibodies A German town had 14% Most asymptomatic...If this is the case, it begins to paint a new path forward for society: If shown to be consistent in additional studies, such high numbers infected would suggest 1) SARS-CoV-2 has a much lower fatality rate than we think (by an order of magnitude or more) 2) Population immunity is already building up Elderly would still remain vulnerable."
He goes on:
US as of today among least vulnerable (<55y) 877 deaths; 231M people. For different assumed % infected (mostly b4 social dist), infection fatality would be: a) 0.1% infected = 0.37% IFR b) 1% = 0.037% c) 10% = 0.0037% d) 30% = 0.0012% Truth most likely near c (or d).
IF 10%+ of population has been infected fatality rates could begin to look tolerable, particularly when weighed against economic collapse But to act on it would require massive PROTECTIONS for the more vulnerable (>55y).
To do so would be exceedingly difficult
But could start painting a path to creatively think up solutions to get people back to work. First though, more sero-prevalence studies are needed to confirm: is it 1% already infected, or 30%, or somewhere between? I think >30 Million (>10%) The next few weeks will tell.
Just to translate that into less telegraphic Twitter language, what Dr. Mina is suggesting, at least as I read him, is that it might perhaps be useful to think about the coronavirus in two different ways. It means one thing, fairly low risk, for people younger than 55: there have now been 877 deaths among that population of roughly 231 million Americans. And it means something else, much riskier, for people older than 55, especially those with pre-existing conditions, including obesity, or those in nursing homes. And a policy implication of this may be to focus on protecting the vulnerable ones without restricting the freedoms of the younger ones in a way that seems wildly out of proportion to their risk.
To the list of studies (New York pregnancies, German town) can be added a Boston homeless shelter where 36% of people (147 out of 408) tested positive for the novel coronavirus, but among those who tested positive only about one out of five showed any symptoms. The fact that so many people who have the virus are asymptomatic makes it harder to slow the spread of the virus, because of the problem of asymptomatic people spreading the virus. But it's also good news, because the more people who are infected, the lower the fatality rate is. If Mina is correct that more than 10% of the U.S. population, or 30 million people, already have this virus, it's a lot less deadlier than we thought. As I wrote about two weeks ago when Mina was speculating about 11 million U.S. cases, "The only way to know whether it's true is to stop testing only very sick people or people who have had a known contact, and instead start doing some random, population-based sample testing."