1. WHO COVID-19 Dashboard. Geneva: World Health Organization, 2020. Available Online: https://covid19.who.int/ (last cited: January 1, 2022).
2. WHO Director-General's opening remarks at the media briefing on COVID-19 - 11 March 2020 https://www.who.int/director-general/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19---11-march-2020 (last cited: January 1, 2022).
3. How COVID-19 spreads? Available Online at: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-covid-spreads.html (last cited: January 1, 2022).
4. CDC. Symptoms of COVID-19. Available online at: https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html (last cited: January 1, 2022).
5. Alimohamadi Y, Sepandi M, Taghdir M, Hosamirudsari H. Determine the most common clinical symptoms in COVID-19 patients: A systematic review and meta-analysis. Journal of Preventive Medicine and Hygiene. 2020 Sep;61(3):E304.
6. Nehme M, Braillard O, Alcoba G, Aebischer Perone S, Courvoisier D, Chappuis F, Guessous I, COVICARE TEAM†. COVID-19 symptoms: Longitudinal evolution and persistence in outpatient settings. Annals of Internal Medicine. 2021 May;174(5):723-5
7. Butcher R, Fenton N. Extending the range of symptoms in a Bayesian Network for the Predictive Diagnosis of COVID-19. medRxiv. 2020 Jan 1. DOI: 10.1101/188.8.131.521755
8. Rajgor DD, Lee MH, Archuleta S, Bagdasarian N, Quek SC. The many estimates of the COVID-19 case fatality rate. Lancet Infectious Diseases. 2020 Jul 1;20(7):776-7.
9. Cortis D. On determining the age distribution of covid-19 pandemic. Frontiers in Public Health. 2020 May 15;8:202.
10. Boehmer TK, DeVies J, Caruso E, van Santen KL, Tang S, Black CL, Hartnett KP, Kite-Powell A, Dietz S, Lozier M, Gundlapalli AV. Changing age distribution of the COVID-19 pandemic—United States, May–August 2020. Morbidity and Mortality Weekly Report. 2020 Oct 2;69(39):1404.
11. World Health Organization EmergensyDashbord, Sudan, 2021. Accessed from: https://covid19.who.int/region/emro/country/sd .
12. Matta S, Chopra KK, Arora VK. Morbidity and mortality trends of Covid 19 in top 10 countries. Indian Journal of Tuberculosis. 2020 Oct 8;67(4S):S167-S172.
13. Salyer SJ, Maeda J, Sembuche S, Kebede Y, Tshangela A, Moussif M, Ihekweazu C, Mayet N, Abate E, Ouma AO, Nkengasong J. The first and second waves of the COVID-19 pandemic in Africa: a cross-sectional study. Lancet. 2021 Apr 3;397(10281):1265-1275.
14. Zheng Z, Peng F, Xu B, Zhao J, Liu H, Peng J, Li Q, Jiang C, Zhou Y, Liu S, Ye C. Risk factors of critical & mortal COVID-19 cases: A systematic literature review and meta-analysis. Journal of infection. 2020 Aug 1;81(2):e16-25.
15. Hafeez S, Din M, Zia F, Ali M, Shinwari ZK. Emerging concerns regarding COVID‐19; second wave and new variant. Journal of Medical Virology. 2021 Jul;93(7):4108.
16. Sudharsanan N, Didzun O, Bärnighausen T, Geldsetzer P. The contribution of the age distribution of cases to COVID-19 case fatality across countries: a nine-country demographic study. Annals of internal medicine. 2020 Nov 3;173(9):714-20.
17. Gebremariam BM, Shienka KL, Kebede BA, Abiche MG. Epidemiological characteristics and treatment outcomes of hospitalized patients with COVID-19 in Ethiopia. The Pan African Medical Journal. 2020;37(Suppl 1).
18. Abdela SG, Abegaz SH, Demsiss W, Tamirat KS, van Henten S, van Griensven J. Clinical profile and treatment of COVID-19 patients: experiences from an Ethiopian treatment center. The American Journal of Tropical Medicine and Hygiene. 2021 Feb;104(2):532.
19. Waya JL, Lako R, Bunga S, Chun H, Mize V, Ambani B, Wamala JF, Guyo AG, Gray JH, Gai M, Maleghemi S. The first sixty days of COVID-19 in a humanitarian response setting: a descriptive epidemiological analysis of the outbreak in South Sudan. The Pan African Medical Journal. 2020;37.
20. Bhopal SS, Bhopal R. Sex differential in COVID-19 mortality varies markedly by age. Lancet. 2020 Aug 22;396(10250):532-3.
21. Byambasuren O, Cardona M, Bell K, Clark J, McLaws ML, Glasziou P. Estimating the extent of asymptomatic COVID-19 and its potential for community transmission: systematic review and meta-analysis. Official Journal of the Association of Medical Microbiology and Infectious Disease Canada. 2020 Dec;5(4):223-34.
22. Yanes-Lane M, Winters N, Fregonese F, Bastos M, Perlman-Arrow S, Campbell JR, Menzies D. Proportion of asymptomatic infection among COVID-19 positive persons and their transmission potential: A systematic review and meta-analysis. PloS one. 2020 Nov 3;15(11):e0241536.
23. O'Reilly GM, Mitchell RD, Rajiv P, Wu J, Brennecke H, Brichko L, Noonan MP, Hiller R, Mitra B, Luckhoff C, Paton A. Epidemiology and clinical features of emergency department patients with suspected COVID‐19: Initial results from the COVID‐19 Emergency Department Quality Improvement Project (COVED‐1). Emergency Medicine Australasia. 2020 Aug;32(4):638-45.
24. Song J, Deng YK, Wang H, Wang ZC, Liao B, Ma J, He C, Pan L, Liu Y, Alobid I, Wang DY, Zeng M, Mullol J, Liu Z. Self-reported Taste and Smell Disorders in Patients with COVID-19: Distinct Features in China. Curr Med Sci. 2021 Feb;41(1):14-23. doi: 10.1007/s11596-021-2312-7. Epub 2021 Feb 13. PMID: 33582900; PMCID: PMC7881907.
25. Beneš J, Džupová O, Poláková A, Sojková N. Repeatedly negative PCR results in patients with COVID-19 symptoms: Do they have SARS-CoV-2 infection or not? Epidemiol Mikrobiol Imunol. 2021 Spring;70(1):3-9. English. PMID: 33853332. https://pubmed.ncbi.nlm.nih.gov/33853332/
26. Jay Mazoomdaar. Explained: Why are several people with Covid symptoms testing negative? Obtained on Jan 10, 2022 from https://indianexpress.com/article/explained/covid-tests-rt-pcr-coronavirus-negative-result-7297329/
27. Kreck M, Scholz E. Proposal of a recursive compartment model of epidemics and applications to the Covid-19 pandemic. arXiv preprint arXiv:2009.00308. 2020 Sep 1.
28. Shim E, Tariq A, Chowell G. Spatial variability in reproduction number and doubling time across two waves of the COVID-19 pandemic in South Korea, February to July, 2020. International Journal of Infectious Diseases. 2021 Jan 1;102:1-9.
29. Alajmi J, Jeremijenko AM, Abraham JC, Alishaq M, Concepcion EG, Butt AA, Abou-Samra AB. COVID-19 infection among healthcare workers in a national healthcare system: The Qatar experience. International Journal of Infectious Diseases. 2020 Nov 1;100:386-9.
30. Sabetian G, Moghadami M, Hashemizadeh Fard Haghighi L, Shahriarirad R, Fallahi MJ, Asmarian N, Moeini YS. COVID-19 infection among healthcare workers: a cross-sectional study in southwest Iran. Virology journal. 2021 Dec;18(1):1-8.