1. Covid-19 second-stage vaccinations to be delayed across UK. Guardian 2020 Dec 30. https://www.theguardian.com/world/2020/dec/30/covid-19-second-stage-nhs-vaccinations-delayed-across-uk
2. Department of Health and Social Care. Optimising the covid-19 vaccination programme for maximum short-term impact. 2021. https://www.gov.uk/government/publications/prioritising-the-first-covid-19-vaccine-dose-jcvi-statement/optimising-the-covid-19-vaccination-programme-for-maximum-short-term-impact
3. Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK
4. UK Government. Covid-19 Greenbook. Chapter 14a. Covid-19-SARS-CoV-2. 2021. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/961287/Greenbook_chapter_14a_v7_12Feb2021.pdf
5. Pfizer. Pfizer-BioNTech covid-19 vaccine (BNT162, PF-07302048). Vaccines And Related Biological Products Advisory Committee briefing document, 10 Dec 2020. https://www.fda.gov/media/144246/download