What does her immunity actually mean though? What other diseases do we try to tackle using herd immunity? How many deaths would make herd immunity acceptable or not acceptable?
There are 350m people in the US. We need to get about 60% of them to have had covid-19. That's 210m people. We don't know how fatal covid-19 is yet, so here are some lower numbers:
0.1% = 210,000 deaths
0.2% = 420,000 deaths
0.5% = 1,050,000 deaths
And once we've killed off all these people what have we achieved? Covid-19 would be in the population and will come back every year as a seasonal respiratory illness, killing off more people every year until we get a vaccine.