Why can't the US just vaccinate all the needed population just once by June 1st 2021?

For one reason there are many people refusing it all together, there are others who got the first dose and don't want the second

You don't see that you are brainwashed? 

Not everyone trusts the vaccine anyway. I'm not taking it until it's FDA-approved. Not because I'm an anti-vaxxer, which I'm not (I don't think vaccines cause autism or some dumb things like that), but because an emergency release by the FDA is not the same as approving it. We don't know enough about it yet. You can't just round people up and force them to take a vaccine, especially if it's just the first dose.

WE DON'T KNOW HOW COVID IMMUNITY WORKS.

Not Biden.  Not even the greatest covid researcher in the world knows how covid immunity works.

Taking both vaccines DOES NOT MAKE THEM FULLY IMMUNE.  It potentially gives them a 95% less chance of getting covid.  For some people it will do nothing!!!

We don't even know if the vaccine will continue to reduce cases April 1st or May 1st or June 1st. 

We KNOW!!!! that the antibodies from the vaccine are already decreasing at 59 days after the 2nd vaccine (Moderna & Pfizer). 

Only 172 people got covid during the vaccine testing about 160 of them in the control group.  This is 66% less than the general population... Thus, when you hear the vaccine is 95% effective it's BS because the people who did testing did not act like the regular general population.  There are some people who say it's only 30% effective in the real life setting (not me... I can't find any literature about what's actually happening in society). 

The only people who are fully immune NOW are the people who got covid in the last few weeks or a couple of months.

You need to try Russian Roulette.

Take a six chamber revolver. Put two bullets into it. That means that your odds of not being shot are 2/3rds.

You good with me triggering that gun at you twice ?

Sure, if there was enough to give everyone the second shot (of those getting the 2 dose type) in a reasonable time period. The first alone isn't nearly effective enough, since the second vaccine exposure is supposed to get a bigger immune response and create the antibodies needed, more-so than the first shot.

Ya but tomorrow is inauguration day and the Coyote catches the Road Runner again 

You're assuming all 270 million will even take it.

You're also underestimating just how far the anti-vaxxers have infected the GQP. The right doesn't trust the vaccine, at least, and thinks it's 'the mark of the beast' at worst. These Idiots comprise half the country, so yea. We're going to be lucky to get 2/3rds

Nobody wants the vaccine,  stop watching establishment news. For your safety.

So you're fine with people dying becsuse you're impatient and don't think production can be increased?