COVID-19 case whether it was mild, moderate or severe — and were conducted before worrisome mutated versions of the virus began circulating.Then Johnson & Johnson tested a single-dose vaccine and didn't count mild illnesses.
J&J's shot was 66 per cent protective against moderate to severe illness in a large international study. In just the US, where there's less spread of variants, it was 72 per cent effective.
More importantly, once the vaccine's effect kicked in it prevented hospitalisation and death.AstraZeneca's two-dose vaccine used in many countries has faced questions about the exact degree of its effectiveness indicated by studies.