1. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study;Zhou;Lancet (London, England),2020
2. COVID-19 coronavirus pandemic. Worldometer Website. Available at: www.worldometers.info/coronavirus 2021
3. NYC Health Database. Available at: https://www1.nyc.gov/site/doh/covid/covid-19-data.page
4. Transmission event of SARS-CoV-2 Delta variant reveals multiple vaccine breakthrough infections;Farinholt;Medrxiv: The Preprint Server for Health Sciences,2021
5. Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant;Lopez Bernal;N Engl J Med,2021