herd immunity
protection from infectious disease that occurs when a sufficient fraction of a population has become immune (through vaccination or previous infections)
en-US/ˈhɝd ˌɪmˈjunəti/
en-GB/ˈhɜːd ɪmjuːnɪtiː/
protection from infectious disease that occurs when a sufficient fraction of a population has become immune (through vaccination or previous infections)