while it still seems it's a minority who question *if* a vaccine will be developed, more and more are coming around to the realization that a covid-19 vax isn't a layup given not only novel (tho necessary) devt approaches but more imp unknowns wrt viral antigens/immune responses https://twitter.com/CharlesMBlow/status/1252977539263447042

good thread overall on this here, but a very key point-

'So with COVID-19, from the very beginning there are limits and alterations in the way SARS-CoV2 is recognized by the immune system.' https://twitter.com/ColumbiaSurgery/status/1252976395829096451