Chair of the Joint Committee on Vaccination and Immunisation (JCVI) Professor Wei Shen Lim, left, Britain's Deputy Chief Medical Officer for England Jonathan Van-Tam and Chief Executive of the Medicines and Healthcare Products Regulatory Agency (MHRA) June Raine, right, attend a media briefing on the latest COVID-19 update at Downing Street, central London, Tuesday Sept. 14, 2021. (Justin Tallis/Pool via AP)