[ 1 ] World Health Organization. Coronavirus disease (COVID-19)—situation report [Internet]. Geneva: World Health Organization; c2020 [cited 2020 Aug 19]. Available from: https://www.who.int/emergencies/diseases/novelcoronavirus-2019/situation-reports. link1

[ 2 ] World Health Organization. International Clinical Trials Registry Platform (ICTRP) [Internet]. Geneva: World Health Organization; c2020 [cited 2020 Aug 19]. Available from: https://www.who.int/ictrp/search/en/. link1

[ 3 ] World Health Organization. Draft landscape of COVID-19 candidate vaccines— 13 August 2020 [Internet]. Geneva: World Health Organization; c2020 [cited 2020 Aug 19]. Available from: https://www.who.int/publications/m/ item/draft-landscape-of-covid-19-candidate-vaccines. link1

[ 4 ] Zhu FC, Li YH, Guan XH, Hou LH, Wang WJ, Li JX, et al. Safety, tolerability, and immunogenicity of a recombinant adenovirus type-5 vectored COVID-19 vaccine: a dose-escalation, open-label, non-randomised, first-in-human trial. Lancet 2020;395(10240):1845–54. link1

[ 5 ] Zhu FC, Guan XH, Li YH, Huang JY, Jiang T, Hou LH, et al. Immunogenicity and safety of a recombinant adenovirus type-5-vectored COVID-19 vaccine in healthy adults aged 18 years or older: a randomised, double-blind, placebocontrolled, phase 2 trial. Lancet 2020;396(10249):479–88. link1

[ 6 ] Folegatti PM, Ewer KJ, Aley PK, Angus B, Becker S, Belij-Rammerstorfer S, et al. Safety and immunogenicity of the ChAdOx1 nCoV-19 vaccine against SARSCoV-2: a preliminary report of a phase 1/2, single-blind, randomised controlled trial. Lancet 2020;396(10249):467–78. link1

[ 7 ] Jackson LA, Anderson EJ, Rouphael NG, Roberts PC, Makhene M, Coler RN, et al. An mRNA vaccine against SARS-CoV-2—preliminary report. N Engl J Med 2020;383:1920–31. link1

[ 8 ] Mulligan MJ, Lyke KE, Kitchin N, Absalon J, Gurtman A, Lockhart S, et al. Phase I/II study of COVID-19 RNA vaccine BNT162b1 in adults. Nature 2020;586 (7830):589–93.

[ 9 ] Xia S, Duan K, Zhang Y, Zhao D, Zhang H, Xie Z, et al. Effect of an inactivated vaccine against SARS-CoV-2 on safety and immunogenicity outcomes: interim analysis of 2 randomized clinical trials. JAMA 2020;324(10):951–60.

[10] Yang J, Zheng Y, Gou X, Pu K, Chen Z, Guo Q, et al. Prevalence of comorbidities and its effects in patients infected with SARS-CoV-2: a systematic review and meta-analysis. Int J Infect Dis 2020;94:91–5. link1

[11] Rubino F, Amiel SA, Zimmet P, Alberti G, Bornstein S, Eckel RH, et al. New-onset diabetes in COVID-19. N Engl J Med 2020;383(8):789–90. link1

[12] Li Bo, Yang J, Zhao F, Zhi L, Wang X, Liu L, et al. Prevalence and impact of cardiovascular metabolic diseases on COVID-19 in China. Clin Res Cardiol 2020;109(5):531–8. link1

[13] Hodgson K, Morris J, Bridson T, Govan B, Rush C, Ketheesan N. Immunological mechanisms contributing to the double burden of diabetes and intracellular bacterial infections. Immunology 2015;144(2):171–85. link1

[14] Allard R, Leclerc P, Tremblay C, Tannenbaum TN. Diabetes and the severity of pandemic influenza A (H1N1) infection. Diabetes Care 2010;33(7):1491–3. link1

[15] Bornstein SR, Rubino F, Khunti K, Mingrone G, Hopkins D, Birkenfeld AL, et al. Practical recommendations for the management of diabetes in patients with COVID-19. Lancet Diabetes Endocrinol 2020;8(6):546–50. link1

[16] Yang JK, Lin SS, Ji XJ, Guo LM. Binding of SARS coronavirus to its receptor damages islets and causes acute diabetes. Acta Diabetol 2010;47(3):193–9. link1

[17] Chandrashekar A, Liu J, Martinot AJ, McMahan K, Mercado NB, Peter L, et al. SARS-CoV-2 infection protects against rechallenge in rhesus macaques. Science 2020;369(6505):812–7. link1

[18] Yu J, Tostanoski LH, Peter L, Mercado NB, McMahan K, Mahrokhian SH, et al. DNA vaccine protection against SARS-CoV-2 in rhesus macaques. Science 2020;369(6505):806–11. link1

[19] Gsell PS, Camacho A, Kucharski AJ, Watson CH, Bagayoko A, Nadlaou SD, et al. Ring vaccination with rVSV-ZEBOV under expanded access in response to an outbreak of Ebola virus disease in Guinea, 2016: an operational and vaccine safety report. Lancet Infect Dis 2017;17(12):1276–84. link1

[20] Agnandji ST, Huttner A, Zinser ME, Njuguna P, Dahlke C, Fernandes JF, et al. Phase 1 trials of rVSV Ebola vaccine in Africa and Europe. N Engl J Med 2016;374(17):1647–60. link1

[21] Wong G, Richardson JS, Pillet S, Patel A, Qiu X, Alimonti J, et al. Immune parameters correlate with protection against Ebola virus infection in rodents and nonhuman primates. Sci Transl Med 2012;4(158). 158ra146. link1

[22] Arunachalam PS, Charles TP, Joag V, Bollimpelli VS, Scott MKD, Wimmers F, et al. T cell-inducing vaccine durably prevents mucosal SHIV infection even with lower neutralizing antibody titers. Nat Med 2020;26(6):932–40. link1

[23] Yang ZY, Werner HC, Kong WP, Leung K, Traggiai E, Lanzavecchia A, et al. Evasion of antibody neutralization in emerging severe acute respiratory syndrome coronaviruses. Proc Natl Acad Sci USA 2005;102(3):797–801. link1

[24] Jin H, Xiao C, Chen Z, Kang Y, Ma Y, Zhu K, et al. Induction of Th1 type response by DNA vaccinations with N, M, and E genes against SARS-CoV in mice. Biochem Biophys Res Commun 2005;328(4):979–86. link1

[25] Ng OW, Chia A, Tan AT, Jadi RS, Leong HN, Bertoletti A, et al. Memory T cell responses targeting the SARS coronavirus persist up to 11 years post-infection. Vaccine 2016;34(17):2008–14. link1

[26] Liebowitz D, Gottlieb K, Kolhatkar NS, Garg SJ, Asher JM, Nazareno J, et al. Efficacy, immunogenicity, and safety of an oral influenza vaccine: a placebocontrolled and active-controlled phase 2 human challenge study. Lancet Infect Dis 2020;20(4):435–44. link1

[27] Van Riet E, Ainai A, Suzuki T, Hasegawa H. Mucosal IgA responses in influenza virus infections; thoughts for vaccine design. Vaccine 2012;30(40):5893–900. link1

[28] Hu KF, Lövgren-Bengtsson K, Morein B. Immunostimulating complexes (ISCOMs) for nasal vaccination. Adv Drug Deliv Rev 2001;51(1–3):149–59. link1

[29] Wu S, Zhong G, Zhang J, Shuai L, Zhang Z, Wen Z, et al. A single dose of an adenovirus-vectored vaccine provides protection against SARS-CoV-2 challenge. Nat Commun 2020;11(1):4081. link1

[30] Epidemiology Working Group for NCIP Epidemic Response, Chinese Center for Disease Control and Prevention. The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China. Chinese J Epidemiol 2020;41(2):145–51. Chinese.

[31] Sharma P, Kumar A. Metabolic dysfunction associated fatty liver disease increases risk of severe COVID-19. Diabetes Metab Syndr 2020;14(5):825–7. link1

[32] Martinez-Ferran M, de la Guía-Galipienso F, Sanchis-Gomar F, Pareja-Galeano H. Metabolic impacts of confinement during the COVID-19 pandemic due to modified diet and physical activity habits. Nutrients 2020;12(6):1549.

[33] Rowland B, Kunadian V. Challenges in the management of older patients with acute coronary syndromes in the COVID-19 pandemic. Heart 2020;106 (17):1296–301. link1

[34] Edelman R, Deming ME, Toapanta FR, Heuser MD, Chrisley L, Barnes RS, et al. The SENIEUR protocol and the efficacy of hepatitis B vaccination in healthy elderly persons by age, gender, and vaccine route. Immun Ageing 2020;17(1):9. link1

[35] Yang J, Zhang J, Han T, Liu C, Li X, Yan L, et al. Effectiveness, immunogenicity, and safety of influenza vaccines with MF59 adjuvant in healthy people of different age groups: a systematic review and meta-analysis. Medicine 2020;99(7):e19095.

[36] Eyal N, Lipsitch M, Smith PG. Human challenge studies to accelerate coronavirus vaccine licensure. J Infect Dis 2020;221(11):1752–6.

[37] World Health Organization. Key criteria for the ethical acceptability of COVID19 human challenge studies [Internet]. Geneva: World Health Organization; c2020 [cited 2020 Aug 19]. Available from: https://www.who.int/ethics/ publications/key-criteria-ethical-acceptability-of-covid-19-human-challenge/ en/. link1