Clinical features of COVID-19 and SARS epidemics. A literature review


COVID-19; SARS-CoV-2; SARS-CoV; SARS; clinical features


SARS-CoV-2, responsible for the current pandemic, is a novel strain of the Coronaviridae family, which has infected humans as a result of the leap to a new species. It causes an atypical pneumonia similar to that caused by SARS-CoV in 2003. SARS-CoV-2 has currently infected more than 9.200.000 people and caused almost 480.000 deaths worldwide. Although SARS-CoV-2 and SARS-CoV have similar phylogenetic and pathogenetic characteristics, they show important differences in clinical manifestations.

We have reviewed the recent literature comparing the characteristics of the two epidemics and highlight their peculiar aspects. An analysis of all signs and symptoms of 3,365 SARS patients and 23,280 COVID-19 patients as well as of the comorbidities has been carried out. A total of 19 and 75 studies regarding patients with SARS and COVID-19, respectively, were included in the analysis. The analysis revealed an overlap of some symptoms between the two infections. Unlike SARS patients, COVID-19 patients have developed respiratory, neurological and gastrointestinal symptoms, and, in a limited number of subjects, symptoms involving organs such as skin and subcutaneous tissue, kidneys, cardiovascular system, liver and eyes.

This analysis was conducted in order to direct towards an early identification of the infection, a suitable diagnostic procedure and the adoption of appropriate containment measures.


[1] WHO: Coronavirus disease (COVID-19) Situation Report – 157, Geneva: Switzerland: World Health Organization; 2020. (accessed on 26 June 2020).
[2] Najafimehr H, Mohamed Ali K, Safari S, Yousefifard M, Hosseini M. Estimation of basic reproduction number for COVID-19 and the reasons for its differences [published online ahead of print, 2020 Apr 16]. Int J Clin Pract 2020. doi:10.1111/ijcp.13518
[3] WHO: Consensus document on the epidemiology of severe acute respiratory syndrome (‎SARS)‎. Geneva: Switzerland: World Health Organization; 2003. (accessed on 16 June 2020).
[4] Peeri NC, Shrestha N, Rahman MS, Zaki R, Tan Z, Bibi S, Baghbanzadeh M, Aghamohammadi N, Zhang W, Haque U. The SARS, MERS and novel coronavirus (COVID-19) epidemics, the newest and biggest global health threats: what lessons have we learned? [published online ahead of print, 2020 Feb 22]. Int J Epidemiol 2020. doi:10.1093/ije/dyaa033
[5] Wu Z, McGoogan JM. Characteristics of and Important Lessons From the Coronavirus Disease 2019 (COVID-19) Outbreak in China: Summary of a Report of 72 314 Cases From the Chinese Center for Disease Control and Prevention [published online ahead of print, 2020 Feb 24]. JAMA 2020. doi:10.1001/jama.2020.2648
[6] Guan WJ, Liang WH, Zhao Y, Liang HR, Chen ZS, Li YM, Liu XQ, Chen RC, Tang CL, Wang T, Ou CQ, Li L, Chen PY, Sang L, Wang W, Li JF, Li CC, Ou LM, Cheng B, Xiong S, Ni ZY, Xiang J, Hu Y, Liu L, Shan H, Lei CL, Peng YX, Wei L, Liu Y, Hu YH, Peng P, Wang JM, Liu JY, Chen Z, Li G, Zheng ZJ, Qiu SQ, Luo J, Ye CJ, Zhu SY, Cheng LL, Ye F, Li SY, Zheng JP, Zhang NF, Zhong NS, He JX. Comorbidity and its impact on 1590 patients with COVID-19 in China: a nationwide analysis. Eur Respir J 2020;55(5):2000547. doi:10.1183/13993003.00547-2020
[7] Chan-Yeung M, Xu RH. SARS: epidemiology. Respirology 2003;8:S9-S14. doi:10.1046/j.1440-1843.2003.00518.x.
[8] Lu R, Zhao X, Li J, Niu P, Yang B, Wu H, Wang W, Song H, Huang B, Zhu N, Bi Y, Ma X, Zhan F, Wang L, Hu T, Zhou H, Hu Z, Zhou W, Zhao L, Chen J, Meng Y, Wang J, Lin Y, Yuan J, Xie Z, Ma J, Liu WJ, Wang D, Xu W, Holmes EC, Gao GF, Wu G, Chen W, Shi W, Tan W. Genomic characterisation and epidemiology of 2019 novel coronavirus: implications for virus origins and receptor binding. Lancet 2020;395(10224):565-574. doi:10.1016/S0140-6736(20)30251-8.
[9] Marra MA, Jones SJ, Astell CR, Holt RA, Brooks-Wilson A, Butterfield YS, Khattra J, Asano JK, Barber SA, Chan SY, Cloutier A, Coughlin SM, Freeman D, Girn N, Griffith OL, Leach SR, Mayo M, McDonald H, Montgomery SB, Pandoh PK, Petrescu AS, Robertson AG, Schein JE, Siddiqui A, Smailus DE, Stott JM, Yang GS, Plummer F, Andonov A, Artsob H, Bastien N, Bernard K, Booth TF, Bowness D, Czub M, Drebot M, Fernando L, Flick R, Garbutt M, Gray M, Grolla A, Jones S, Feldmann H, Meyers A, Kabani A, Li Y, Normand S, Stroher U, Tipples GA, Tyler S, Vogrig R, Ward D, Watson B, Brunham RC, Krajden M, Petric M, Skowronski DM, Upton C, Roper RL. The Genome sequence of the SARS-associated coronavirus. Science 2003;300(5624):1399-1404. doi:10.1126/science.1085953
[10] Sah R, Rodriguez-Morales AJ, Jha R, Chu DKW, Gu H, Peiris M, Bastola A, Lal BK, Ojha HC, Rabaan AA, Zambrano LI, Costello A, Morita K, Pandey BD, Poon LLM. Complete Genome Sequence of a 2019 Novel Coronavirus (SARS-CoV-2) Strain Isolated in Nepal. Microbiol Resour Announc 2020;9(11):e00169-20. doi:10.1128/MRA.00169-20
[11] Zhao Z, Li H, Wu X, Zhong Y, Zhang K, Zhang YP, Boerwinkle E, Fu YX. Moderate mutation rate in the SARS coronavirus genome and its implications. BMC Evol Biol 2004;4:21. doi:10.1186/1471-2148-4-21
[12] Lai A, Bergna A, Acciarri C, Galli M, Zehender G. Early phylogenetic estimate of the effective reproduction number of SARS-CoV-2. J Med Virol 2020;92(6):675-679. doi:10.1002/jmv.25723
[13] Guangdong Public Health Office. 2003: Document No 2. Summary report of investigating an atypical pneumonia outbreak in Zhongshan. 2003.
[14] WHO: Update 95 – SARS: Chronology of a serial killer. Geneva: Switzerland: World Health Organization; 2003. (accessed on 31 May 2020).
[15] Zhong NS, Wong GW. Epidemiology of severe acute respiratory syndrome (SARS): adults and children. Paediatr Respir Rev 2004;5(4):270-274. doi:10.1016/j.prrv.2004.07.011
[16] WHO: Summary table of SARS cases by country, 1 November 2002 - 7 August 2003. Geneva: Switzerland: World Health Organization; ‎2003. (accessed 31 May 2020).
[17] WHO: Summary of probable SARS cases with onset of illness from 1 November 2002 to 31 July 2003. Geneva: Switzerland: World Health Organization; ‎2003. (accessed 02 June 2020).
[18] Wuhan Municipal Health Commission: Report of clustering pneumonia of unknown etiology in Wuhan City. Wuhan, China Wuhan Municipal Health Commission. (accessed 02 June 2020).
[19] Xu J, Zhao S, Teng T, Abdalla AE, Zhu W, Xie L, Wang Y, Guo X. Systematic Comparison of Two Animal-to-Human Transmitted Human Coronaviruses: SARS-CoV-2 and SARS-CoV. Viruses 2020;12(2):244. doi:10.3390/v12020244.
[20] Gralinski LE, Menachery VD. Return of the Coronavirus: 2019-nCoV. Viruses 2020;12(2):135. doi:10.3390/v12020135.
[21] WHO: Statement on the second meeting of the International Health Regulations (2005) Emergency Committee regarding the outbreak of novel coronavirus (2019-nCoV). Geneva: Switzerland: World Health Organization; 2020. (accessed 05 June 2020).
[22] van Doremalen N, Bushmaker T, Morris DH, Holbrook MG, Gamble A, Williamson BN, Tamin A, Harcourt JL, Thornburg NJ, Gerber SI, Lloyd-Smith JO, de Wit E, Munster VJ. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. N Engl J Med 2020;382(16):1564-1567. doi:10.1056/NEJMc2004973
[23] WHO. First data on stability and resistance of SARS coronavirus completed by members of WHP laboratory network. Geneva: Switzerland: World Health Organization; 2003. (accessed 09 June 2020).
[24] European Centre for Disease Prevention and Control. Interim guidance for environmental cleaning in nonhealthcare facilities exposed to SARS-CoV-2. Stockholm: ECDC; 2020. (accessed 12 June 2020).
[25] Xia J, Tong J, Liu M, Shen Y, Guo D. Evaluation of coronavirus in tears and conjunctival secretions of patients with SARS-CoV-2 infection. J Med Virol 2020;92(6):589-594. doi:10.1002/jmv.25725.
[26] Loon SC, Teoh SC, Oon LL, Se-Thoe SY, Ling AE, Leo YS, Leong HN. The severe acute respiratory syndrome coronavirus in tears. Br J Ophthalmol 2004;88(7):861-863. doi:10.1136/bjo.2003.035931
[27] Wu P, Duan F, Luo C, Liu Q, Qu X, Liang L, Wu K. Characteristics of Ocular Findings of Patients With Coronavirus Disease 2019 (COVID-19) in Hubei Province, China [published online ahead of print, 2020 Mar 31]. JAMA Ophthalmol 2020;138(5):575-578. doi:10.1001/jamaophthalmol.2020.1291
[28] Mcintosh K. Coronavirus: a comparative review. Curr Top Microbiol 1974;63:85-129.
[29] Chen Y, Chen L, Deng Q, Zhang G, Wu K, Ni L, Yang Y, Liu B, Wang W, Wei C, Yang J, Ye G, Cheng Z. The presence of SARS-CoV-2 RNA in the feces of COVID-19 patients. J Med Virol 2020;92(7):833-840. doi:10.1002/jmv.25825
[30] Cheung KS, Hung IFN, Chan PPY, Lung KC, Tso E, Liu R, Ng YY, Chu MY, Chung TWH, Tam AR, Yip CCY, Leung KH, Fung AY, Zhang RR, Lin Y, Cheng HM, Zhang AJX, To KKW, Chan KH, Yuen KY, Leung WK. Gastrointestinal Manifestations of SARS-CoV-2 Infection and Virus Load in Fecal Samples From a Hong Kong Cohort: Systematic Review and Meta-analysis [published online ahead of print, 2020 Apr 3]. Gastroenterology 2020;S0016-5085(20)30448-0. doi:10.1053/j.gastro.2020.03.065
[31] Wong SF, Chow KM, Leung TN, Ng WF, Ng TK, Shek CC, Ng PC, Lam PW, Ho LC, To WW, Lai ST, Yan WW, Tan PY. Pregnancy and perinatal outcomes of women with severe acute respiratory syndrome. Am J Obstet Gynecol 2004;191(1):292-297. doi:10.1016/j.ajog.2003.11.019
[32] Chen H, Guo J, Wang C, Luo F, Yu X, Zhang W, Li J, Zhao D, Xu D, Gong Q, Liao J, Yang H, Hou W, Zhang Y. Clinical characteristics and intrauterine vertical transmission potential of COVID-19 infection in nine pregnant women: a retrospective review of medical records. Lancet 2020;395(10226):809-815. doi:10.1016/S0140-6736(20)30360-3
[33] Wilder-Smith A, Teleman MD, Heng BH, Earnest A, Ling AE, Leo YS. Asymptomatic SARS coronavirus infection among healthcare workers, Singapore. Emerg Infect Dis 2005;11(7):1142-1145. doi:10.3201/eid1107.041165
[34] Tian S, Hu N, Lou J, Chen K, Kang X, Xiang Z, Chen H, Wang D, Liu N, Liu D, Chen G, Zhang Y, Li D, Li J, Lian H, Niu S, Zhang L, Zhang J. Characteristics of COVID-19 infection in Beijing. J Infect 2020;80(4):401-406. doi:10.1016/j.jinf.2020.02.018
[35] Day M. Covid-19: four fifths of cases are asymptomatic, China figures indicate. BMJ 2020;369:m1375. doi:10.1136/bmj.m1375
[36] Hilgenfeld R, Peiris M. From SARS to MERS: 10 years of research on highly pathogenic human coronaviruses. Antiviral Res 2013;100(1):286-295. doi:10.1016/j.antiviral.2013.08.015
[37] Zou L, Ruan F, Huang M, Liang L, Huang H, Hong Z, Yu J, Kang M, Song Y, Xia J, Guo Q, Song T, He J, Yen HL, Peiris M, Wu J. SARS-CoV-2 Viral Load in Upper Respiratory Specimens of Infected Patients. N Engl J Med 2020;382(12):1177-1179. doi:10.1056/NEJMc2001737
[38] Lauer SA, Grantz KH, Bi Q, Jones FK, Zheng Q, Meredith HR, Azman AS, Reich NG, Lessler J. The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application. Ann Intern Med 2020;172(9):577-582. doi:10.7326/M20-0504
[39] Lessler J, Reich NG, Brookmeyer R, Perl TM, Nelson KE, Cummings DA. Incubation periods of acute respiratory viral infections: a systematic review. Lancet Infect Dis 2009;9(5):291-300. doi:10.1016/S1473-3099(09)70069-6
[40] Cai J, Xu J, Lin D, Yang Z, Xu L, Qu Z, Zhang Y, Zhang H, Jia R, Liu P, Wang X, Ge Y, Xia A, Tian H, Chang H, Wang C, Li J, Wang J, Zeng M. A Case Series of children with 2019 novel coronavirus infection: clinical and epidemiological features [published online ahead of print, 2020 Feb 28]. Clin Infect Dis 2020;ciaa198. doi:10.1093/cid/ciaa198
[41] Bauch CT, Lloyd-Smith JO, Coffee MP, Galvani AP. Dynamically modeling SARS and other newly emerging respiratory illnesses: past, present, and future. Epidemiology 2005;16(6):791-801. doi:10.1097/01.ede.0000181633.80269.4c
[42] Liu Y, Gayle AA, Wilder-Smith A, Rocklöv J. The reproductive number of COVID-19 is higher compared to SARS coronavirus. J Travel Med 2020;27(2):taaa021. doi:10.1093/jtm/taaa021
[43] Li W, Moore MJ, Vasilieva N, Sui J, Wong SK, Berne MA, Somasundaran M, Sullivan JL, Luzuriaga K, Greenough TC, Choe H, Farzan M. Angiotensin-converting enzyme 2 is a functional receptor for the SARS coronavirus. Nature 2003;426(6965):450-454. doi:10.1038/nature02145
[44] Zhou P, Yang XL, Wang XG, Hu B, Zhang L, Zhang W, Si HR, Zhu Y, Li B, Huang CL, Chen HD, Chen J, Luo Y, Guo H, Jiang RD, Liu MQ, Chen Y, Shen XR, Wang X, Zheng XS, Zhao K, Chen QJ, Deng F, Liu LL, Yan B, Zhan FX, Wang YY, Xiao GF, Shi ZL. A pneumonia outbreak associated with a new coronavirus of probable bat origin. Nature 2020;579(7798):270-273. doi:10.1038/s41586-020-2012-7
[45] Mason RJ. Pathogenesis of COVID-19 from a cell biology perspective. Eur Respir J 2020;55(4):2000607. doi:10.1183/13993003.00607-2020
[46] Wrapp D, Wang N, Corbett KS, Goldsmith JA, Hsieh CL, Abiona O, Graham BS, McLellan JS. Cryo-EM structure of the 2019-nCoV spike in the prefusion conformation. Science 2020;367(6483):1260-1263. doi:10.1126/science.abb2507
[47] Hui DS, Wong PC, Wang C. SARS: clinical features and diagnosis. Respirology. 2003;8 :S20-S24. doi:10.1046/j.1440-1843.2003.00520.x
[48] Cheng VC, Lau SK, Woo PC, Yuen KY. Severe acute respiratory syndrome coronavirus as an agent of emerging and reemerging infection. Clin Microbiol Rev 2007;20(4):660-694. doi:10.1128/CMR.00023-07
[49] Richardson S, Hirsch JS, Narasimhan M, Crawford JM, McGinn T, Davidson KW; and the Northwell COVID-19 Research Consortium. Presenting Characteristics, Comorbidities, and Outcomes Among 5700 Patients Hospitalized With COVID-19 in the New York City Area. JAMA 2020;323(20):2052-2059. doi:10.1001/jama.2020.6775
[50] Guan WJ, Ni ZY, Hu Y, Liang WH, Ou CQ, He JX, Liu L, Shan H, Lei CL, Hui DSC, Du B, Li LJ, Zeng G, Yuen KY, Chen RC, Tang CL, Wang T, Chen PY, Xiang J, Li SY, Wang JL, Liang ZJ, Peng YX, Wei L, Liu Y, Hu YH, Peng P, Wang JM, Liu JY, Chen Z, Li G, Zheng ZJ, Qiu SQ, Luo J, Ye CJ, Zhu SY, Zhong NS; China Medical Treatment Expert Group for Covid-19. Clinical Characteristics of Coronavirus Disease 2019 in China. N Engl J Med 2020;382(18):1708-1720. doi:10.1056/NEJMoa2002032
[51] van Kasteren PB, van der Veer B, van den Brink S, Wijsman L, de Jonge J, van den Brandt A, Molenkamp R, Reusken CBEM, Meijer A. Comparison of seven commercial RT-PCR diagnostic kits for COVID-19. J Clin Virol 2020;128:104412. doi:10.1016/j.jcv.2020.104412
[52] Yong SEF, Anderson DE, Wei WE, Pang J, Chia WN, Tan CW, Teoh YL, Rajendram P, Toh MPHS, Poh C, Koh VTJ, Lum J, Suhaimi NM, Chia PY, Chen MI, Vasoo S, Ong B, Leo YS, Wang L, Lee VJM. Connecting clusters of COVID-19: an epidemiological and serological investigation. Lancet Infect Dis 2020;20(7):809-815. doi:10.1016/S1473-3099(20)30273-5
[53] Lou B, Li TD, Zheng SF, Su YY, Li ZY, Liu W, Yu F, Ge SX, Zou QD, Yuan Q, Lin S, Hong CM, Yao XY, Zhang XJ, Wu DH, Zhou GL, Hou WH, Li TT, Zhang YL, Zhang SY, Fan J, Zhang J, Xia NS, Chen Y. Serology characteristics of SARS-CoV-2 infection since exposure and post symptom onset. Eur Respir J 2020;2000763. doi:10.1183/13993003.00763-2020
[54] Cassaniti I, Novazzi F, Giardina F, Salinaro F, Sachs M, Perlini S, Bruno R, Mojoli F, Baldanti F; Members of the San Matteo Pavia COVID-19 Task Force. Performance of VivaDiag COVID-19 IgM/IgG Rapid Test is inadequate for diagnosis of COVID-19 in acute patients referring to emergency room department. J Med Virol 2020;10.1002/jmv.25800. doi:10.1002/jmv.25800
[55] Winter AK, Hegde ST. The important role of serology for COVID-19 control. Lancet Infect Dis 2020;20(7):758-759. doi:10.1016/S1473-3099(20)30322-4
[56] Kahneman D, Tversky A. Choices, values, and frames. Am Psychol 1984;39:341–50.
[57] Lagier JC, Colson P, Tissot Dupont H, Salomon J, Doudier B, Aubry C, Gouriet F, Baron S, Dudouet P, Flores R, Ailhaud L, Gautret P, Parola P, La Scola B, Raoult D, Brouqui P. Testing the repatriated for SARS-Cov2: Should laboratory-based quarantine replace traditional quarantine?. Travel Med Infect Dis 2020;34:101624. doi:10.1016/j.tmaid.2020.101624
[58] Reusken CBEM, Broberg EK, Haagmans B, Meijer A, Corman VM, Papa A, Charrel R, Drosten C, Koopmans M, Leitmeyer K, On Behalf Of Evd-LabNet And Erli-Net. Laboratory readiness and response for novel coronavirus (2019-nCoV) in expert laboratories in 30 EU/EEA countries, January 2020. Euro Surveill 2020;25(6):2000082. doi:10.2807/1560-7917.ES.2020.25.6.200008
[59] Flaxman S, Mishra S, Gandy A, Unwin HJT, Mellan TA, Coupland H, Whittaker C, Zhu H, Berah T, Eaton JW, Monod M; Imperial College COVID-19 Response Team, Ghani AC, Donnelly CA, Riley SM, Vollmer MAC, Ferguson NM, Okell LC, Bhatt S. Estimating the effects of non-pharmaceutical interventions on COVID-19 in Europe. Nature 2020 Jun 8. doi: 10.1038/s41586-020-2405-7
[60] Qualls N, Levitt A, Kanade N, Wright-Jegede N, Dopson S, Biggerstaff M, Reed C, Uzicanin A; CDC Community Mitigation Guidelines Work Group. Community Mitigation Guidelines to Prevent Pandemic Influenza - United States, 2017. MMWR Recomm Rep 2017;66(1):1-34. doi:10.15585/mmwr.rr6601a1
[61] Mackolil J, Mackolil J. Addressing psychosocial problems associated with the COVID-19 lockdown [published online ahead of print, 2020 May 8]. Asian J Psychiatr 2020;51:102156. doi:10.1016/j.ajp.2020.102156