As of today 28 million KNOWN cases of covid confirmed. Add in millions of cases asymptomatic and symptomatic where the person CHOSE NOT to get tested and you have over 30 million people already exposed and presumably now have anti-bodies. Who knows how long those last? Then as of a day ago we vaccinated nearly 52 million citizens and are vaccinating 1.67 million daily and that number is expected to rise. So if we add the 2 together we are probably close (or getting close) to 100 million citizens with anti-bodies. It is getting harder for the virus to find hosts. The more vaccinated and the more recovered, then the more anti bodies DAILY!