1. ClinicalTrials.gov. Summary of listed covid-19 studies. 11 Jul 2022. https://clinicaltrials.gov/ct2/covid_view
2. Recovery trial. Information for site staff. No of participants. 19 Dec 2022. https://www.recoverytrial.net/for-site-staff
3. American Medical Association. Covid-19 vaccine trials: 1 million more volunteers still needed. 2020. https://www.ama-assn.org/delivering-care/public-health/covid-19-vaccine-trials-1-million-more-volunteers-still-needed
4. Royal Family. The royal family thank those involved in the UK vaccine rollout. 2021. https://www.royal.uk/royal-family-thank-those-involved-uk-vaccine-rollout
5. Four former surgeons general join call for “national vaccine day.” ABC News 18 Feb 2021.https://abcnews.go.com/US/surgeons-general-join-call-national-vaccine-day/story?id=76187403