I think they are referring to the tests in South Africa on young people that show it has very low effectiveness against the variant that is prevalent there: ht

I think they are referring to the tests in South Africa on young people that show it has very low effectiveness against the variant that is prevalent there: https://www.cidrap.umn.edu/news-perspective/2021/03/astrazeneca-vaccine-doesnt-prevent-b1351-covid-early-trial https://www.cidrap.umn.edu/news-perspective/2021/03/astrazen...