Herd Immunity? Maybe Never, Experts Now Say

When the COVID-19 pandemic first swept the U.S. more than a year ago, Americans learned a brand-new term: Herd immunity.

The idea is simple: If enough people get a virus or a vaccine — thus building antibodies — the spread of the virus drops off precipitously.

While experts didn’t know exactly how many Americans would need antibodies to reach herd immunity, the number ranged from more than 50% to upwards of 70%. Early on in the pandemic, Dr. Anthony Fauci, the top U.S. immunologist, put the number at 60% to 70%, but in April he started upping that number, saying in an interview with CNBC News that it would be “75, 80, 85 percent.”