There are two competing playbooks for managing US #covid #pandemic. First is the old one, which says herd immunity for a population occurs after about 60% are infected. That threshold is higher if a virus is highly transmissible. Using this playbook, worst case scenario

is that ~345,000 Americans will die before herd immunity reached. Hospitals will be overrun. #Vaccine is best/only hope. This is what government officials faced last March. They tried to encourage with promise of vaccine soon. Situation was bleak.

Since then covid has surprised us. In hard hit places, the #virus has been devastating, but has subsided long before the 60% threshold. In #Stockholm, it subsided after about 15% infected, and without lockdown. Very confusing. Except prominent US scientist @MLevitt_NP2013

had observed the virus in Asia and predicted some of this behavior. He specializes in complex biological systems and won the Nobel Prize for science in 2013. Other scientists have also tried to understand why the virus abates when it does, and are beginning to

paint a complicated but credible picture of a complex interplay involving innate (and adaptive) #immunity, risk factors, living conditions, and other variables. Unlike the Spanish flu pandemic, young people seem to be at exceedingly low risk. All of this gets us to playbook 2

which says we only need to get 15-20% of the population infected before herd immunity reached. If we could infect the 15-20% at lowest risk, that is easiest way to end of pandemic. It’s a no brainer. Problems with this idea include that it is new theory, not widely accepted, and

necessarily involves exposing our kids and young people (lowest risk population) to infection. In the background, we are learning more about the long term effects the virus can have on brain, lungs, and vascular system. If playbook 2 is right

lockdowns and school closures are the exact wrong thing to do. If playbook 2 is wrong, we could be exposing our kids to as yet undefined long term morbidity. If you are in charge of making public policy, what is your decision? The clocks ticking. Virus may be harsher in winter

Whichever turns out to be the case, we still have a way to go. Using best guess metrics, US appears 2/3 to 3/4 through pandemic with pain left. When you watch the news, see if you can spot who is with playbook 1 and who is with playbook 2

On second thought, turn off the news....