AstraZeneca announced Monday that positive high-level results from an interim analysis of clinical trials of the COVID-19 vaccine candidate in the UK and Brazil showed it was highly effective in preventing the disease, the primary endpoint, and no hospitalisations or severe cases of the disease were reported in participants receiving the vaccine. There were a total of 131 COVID-19 cases in the interim analysis.

One dosing regimen showed vaccine efficacy of 90 per cent when AZD1222 was given as a half dose, followed by a full dose at least one month apart, and another dosing regimen showed 62 per cent efficacy when given as two full doses at least one month apart. The combined analysis from both dosing regimens resulted in an average efficacy of 70 per cent.