蜜芽传媒

Dr Anthony Fauci, chief medical adviser to President Joe Biden, has said that herd immunity is an "elusive concept" and there is no definitive percentage of the population that needs to be vaccinated to achieve it.

He told 蜜芽传媒 Radio 4 Today that a return to normality would be gradual, and is "not going to be like a light switch going on and off."