herd immunity - when most of a population is immune to an infectious disease Articles found: Covid-19 becoming a seasonal bug (13/12/2022) Herd immunity against virus at 50% (20/04/2022) Tourism ministry sets January date to reopen (06/09/2021) Thai tourists needed in Phuket (01/09/2021) Pattaya reopening likely to be delayed (02/08/2021)