vaccines require two doses per person...let's assume that we get to ~75% of the U.S. population vaccinated...that's ~250M people, or 500M doses (btw, I acknowledge that other vaccines will come on line and only require one dose (but with lower efficacy (e.g. ~60-70%))...
From the linked article (dated 12/3/2020)...
"Operation Warp Speed Chief Operating Officer Gus Perna has said that the U.S. will distribute 40 million vaccine doses total by the end of the year, enough for 20 million people."
So that's 40M/mo. from Pfizer...now add Moderna at a similar production rate (an assumption)...we're up to 80M/mo...forgetting other vaccines for the moment, that equates to 6 months to vaccinate 75% of the U.S. population...we'll certainly do better, I'm sure, but let's not forget that Pfizer ran into critical supply issues which could happen again, and not just for them...that 6 months takes us to 'Late Spring' and possibly 'Early Summer' to get the necessary 75% vaccinated.
More and better data will be coming weekly, if not daily, so timelines will change...but at the moment, a conservative estimate of reaching the crucial 75% target is not February...it's more like May or June...and brace for it....possibly September. Let's all pray that doesn't happen.
Let's also remember that we are dealing with a Worldwide Pandemic...Pfizer, Moderna, and all the other vaccine providers are serving literally Billions of people...they'll have contracts with them as well and it will test our ability to "cooperate" internationally.
Hope this helps...comments welcomed.
Link: https://time.com/5917847/pfizer-cut-covid-19-vaccine-targets/