Reference
1. Huang C, Wang Y, Li X, et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet 2020;395:497-506
2. Guan WJ, Ni ZY, Hu Y, et al. Clinical Characteristics of Coronavirus Disease 2019 in China. N Engl J Med 2020; https://DOI: 10.1056/NEJMoa2002032
3. World Health Organization. Coronavirus disease (COVID-2019) situation reports-112. Available at:https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200511-covid-19-sitrep-112.pdf?sfvrsn=813f2669_2 . Accessed May 13.
4. Nikolich-Zugich J, Knox KS, Rios CT, et al. SARS-CoV-2 and COVID-19 in older adults: what we may expect regarding pathogenesis, immune responses, and outcomes. GeroScience 2020. https://doi.org/10.1007/s11357-020-00186-0
5. Rokni M, Ghasemi V, Tavakoli Z. Immune responses and pathogenesis of SARS-CoV-2 during an outbreak in Iran: Comparison with SARS and MER. Rev Med Virol 2020; https://10.1002/rmv.2107
6. Hou H, Wang T, Zhang B, et al. Detection of IgM and IgG antibodies in patients with coronavirus disease 2019. Clinical & Translational Immunology 2020; e1136. https://doi: 10.1002/cti2.1136
7. Zhao Z, Yuan Q, Wang H, et al. Antibody responses to SARS-CoV-2 in patients of novel coronavirus disease 2019. Clin Infect Dis 2020; https://doi:10.1093/cid/ciaa344
8. Xiang F, Wang X, He X, et al. Antibody Detection and Dynamic Characteristics in Patients with COVID. Clin Infect Dis 2020; https:// doi:10.1093/cid/ciaa461
9. World Health Organization. Clinical management of severe acute respiratory infection when novel coronavirus (2019-nCoV) infection is suspected: interim guidance. Available at: (https://www.who.int/publications-detail/global-surveillance-for-human-infection-with-novel-coronavirus-(2019-ncov)). Accessed May 13 2020
10. Metlay JP, Waterer GW, Long AC, et al. Diagnosis and treatment of adults with community-acquired pneumonia: An official clinical practice guideline of the American Thoracic Society and Infectious Disease Society of America. Am J Respir Crit Care Med 2019;200:e45-e67
11. Xu G, Zhao J, Zhang F, et al. Favorable outcomes of elderly COVID-19 patients in Guangzhou, China: a retrospective, observational study. Research square 2020. https://doi. 10.21203/rs.3.rs-26511/v1
  1. Hu y, Shen L, Yao Y, et al. A report of three COVID-19 cases with prolonged viral RNA detection in anal swabs. Clin Microbiol Infect 2020. https://doi.10.1016/j.cmi.2020.04.010
  2. Wu J, Liu J, Li S, et al. Detection and analysis of nucleic acid in various biological samples of COVID-19 patients. Travel Med Infect Dis 2020. https://doi.10167310.1016/j.tmaid.2020.101673