COVID-19 Double-Decrement Model Forecasting for South Korean Population

Christian Evan Chandra, Sarini Abdullah


Since the first case in November 2019, COVID-19 has spread fast, infected many people, and taken many lives. Once COVID-19 cases are confirmed, and hospital treatments are required, they will need high costs yet still be at risk of death. Therefore, insurance companies and social service providers need a reliable model to estimate the expenses and ensure their financial health. This study discusses the modeling of time-until-release and time-until-death since cases are confirmed, using the South Korean data. Double-decrement model is assumed to follow Weibull and log-logistic hazard for time-until-release and time-until-death, respectively. Considered risk factors are sex, symptoms, age group, and the month when the case is confirmed. The nonlinear survival regression model is proposed, with the Solver function in Microsoft Excel for parameter estimation. The results suggest that virus lifespan and mortality risk get lower over time. Time-until-death is also lower, implying that we have less time to save lives from mortality risk. More frequent testing with faster results and not waiting for the symptoms to occur is needed for people under thirty years old due to shorter time-until-death and those at sixty and above due to higher case fatality rates. Full dose vaccination must be prioritized for ages sixty and above to save as many lives as possible.


Pandemic modeling; survival regression; time series modeling.

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P. Romagnani et al., “The COVID-19 infection: lessons from the Italian experience,†J. Public Health Policy, vol. 41, pp. 2338–244, 2020, Accessed: July 06, 2021. [Online]. Available:

N. Suntronwong et al., “Impact of COVID-19 public health interventions on influenza incidence in Thailand,†Pathog. Glob. Health, vol. 114, no. 5, pp. 225–227, Jul. 2020, doi: 10.1080/20477724.2020.1777803.

Agustiyanti, “Obral tiket pesawat imbas corona, Jakarta-Yogyakarta mulai Rp 300 ribu ,†, Mar. 01, 2020. (accessed Jul. 06, 2021).

M. McArdle, “Pence announces insurance companies agreed to waive co-pays for coronavirus testing,†, March 10, 2020. (accessed July 06, 2021).

J. Whitworth, “COVID-19: a fast evolving pandemic,†R. Soc. Trop. Med. Hyg., vol. 114, no. 4, p. 241, 2020, Accessed: July 06, 2021. [Online]. Available:

S. Rab, M. Javaid, A. Haleem, and R. Vaishya, “Face masks are new normal after COVID-19 pandemic,†Diabetes Metab. Syndr. Clin. Res. Rev., vol. 14, no. 6, pp. 1617–1619, Nov. 2020, doi: 10.1016/j.dsx.2020.08.021.

B. Kennelly et al., “The COVID-19 pandemic in Ireland: An overview of the health service and economic policy response,†Heal. Policy Technol., vol. 9, no. 4, pp. 419–429, Dec. 2020, doi: 10.1016/j.hlpt.2020.08.021.

N. Ntounis, C. Mumford, M. Loroño-Leturiondo, C. Parker, and K. Still, “How safe is it to shop? Estimating the amount of space needed to safely social distance in various retail environments,†Saf. Sci., vol. 132, Dec. 2020, doi: 10.1016/j.ssci.2020.104985.

D. Rauf, “Vaccinated people can go mask-free in most cases, CDC says | Everyday Health,†, May 14, 2021. (accessed July 06, 2021).

R. Horton, “Offline: The case for no-COVID,†Lancet, vol. 397, no. 10272, p. 359, Jan. 2021, doi: 10.1016/S0140-6736(21)00186-0.

H. A. Baker, S. A. Safavynia, and L. A. Evered, “The ‘third wave’: impending cognitive and functional decline in COVID-19 survivors,†Br. J. Anaesth., vol. 126, no. 1, pp. 44–47, Jan. 2021, doi: 10.1016/j.bja.2020.09.045.

S. Widianto and F. Nangoy, “Emergency tents erected outside Jakarta hospitals as virus cases surge | Reuters,†, June 25, 2021. (accessed July 06, 2021).

K. Lokuge et al., “Exit strategies: optimising feasible surveillance for detection, elimination, and ongoing prevention of COVID-19 community transmission,†BMC Med., vol. 19, no. 1, pp. 1–14, Dec. 2021, doi: 10.1186/s12916-021-01934-5.

M. E. Kretzschmar, G. Rozhnova, and M. van Boven, “Isolation and contact tracing can tip the scale to containment of COVID-19 in populations with social distancing,†Front. Phys., vol. 8, p. 677, Feb. 2021, doi: 10.3389/fphy.2020.622485.

B. Jamshidi, Z. Jamshidi, H. Bekrizadeh, M. Rezaei, and F. Najafi, “Comparing length of hospital stay during COVID-19 pandemic in the USA, Italy and Germany,†Int. J. Qual. Heal. Care, vol. 33, no. 1, p. mzab050, 2021, Accessed: July 06, 2021. [Online]. Available:

B. Vekaria et al., “Hospital length of stay for COVID-19 patients: Data-driven methods for forward planning,†2021. Accessed: July 06, 2021. [Online]. Available:

E. M. Rees et al., “COVID-19 length of hospital stay: A systematic review and data synthesis,†BMC Med., vol. 18, no. 1, Sep. 2020, doi: 10.1186/s12916-020-01726-3.

H. Alwafi et al., “Predictors of length of hospital stay, mortality, and outcomes among hospitalised COVID-19 patients in Saudi Arabia: A cross-sectional study,†J. Multidiscip. Healthc., vol. 14, pp. 839–852, Apr. 2021, doi: 10.2147/JMDH.S304788.

A. Guo et al., “Risk factors on admission associated with hospital length of stay in patients with COVID-19: a retrospective cohort study,†Sci. Rep., vol. 11, no. 1, pp. 1–7, 2021, Accessed: July 06, 2021. [Online]. Available:

G. Thiruvengadam, M. Lakshmi, and R. Ramanujam, “A study of factors affecting the length of hospital stay of COVID-19 patients by Cox-Proportional Hazard model in a South Indian Tertiary Care Hospital,†J. Prim. Care Community Heal., vol. 12, Mar. 2021, doi: 10.1177/21501327211000231.

E. M. Harrison, A. Docherty, and C. Semple, “COVID-19: time from symptom onset until death in UK hospitalised patients,†Oct. 2020.

V. Verma, R. K. Vishwakarma, A. Verma, D. C. Nath, and H. T. A. Khan, “Time-to-Death approach in revealing chronicity and severity of COVID-19 across the World,†PLoS One, vol. 15, no. 5, p. e0233074, May 2020, doi: 10.1371/journal.pone.0233074.

G. J. B. Sousa, T. S. Garces, V. R. F. Cestari, R. S. Florêncio, T. M. M. Moreira, and M. L. D. Pereira, “Mortality and survival of COVID-19,†Epidemiol. Infect., vol. 148, 2020, doi: 10.1017/S0950268820001405.

Y. Chen, T. Li, Y. Ye, Y. Chen, and J. Pan, “Impact of fundamental diseases on patients with COVID-19,†Disaster Med. Public Health Prep., vol. 14, no. 6, pp. 776–781, Dec. 2020, doi: 10.1017/dmp.2020.139.

I. Voinsky, G. Baristaite, and D. Gurwitz, “Effects of age and sex on recovery from COVID-19: Analysis of 5769 Israeli patients,†J. Infect., vol. 81, no. 2, pp. e102–e103, Aug. 2020, doi: 10.1016/j.jinf.2020.05.026.

NeurIPS 2020, “Data Science for COVID-19,†, 2020. (accessed July 06, 2021).

S. Park, G. J. Choi, and H. Ko, “Information Technology-Based Tracing Strategy in Response to COVID-19 in South Korea - Privacy Controversies,†JAMA - J. Am. Med. Assoc., vol. 323, no. 21, pp. 2129–2130, Jun. 2020, doi: 10.1001/jama.2020.6602.

N. L. Bowers, H. U. Gerber, J. C. Hickman, D. A. Jones, and C. J. Nesbitt, Actuarial Mathematics, 2nd ed. Society of Actuaries, 1997.

A. N. Baldwin, “Doctors rush to understand COVID-19’s second-week crash - ABC News,†abcNEWS, May 06, 2020. (accessed July 06, 2021).

J. P. Klein and M. L. Moeschberger, Survival analysis: techniques for censored and truncated data, vol. 1230. Springer, 2003.

S. Mishra, S. Padhy, S. N. Mishra, and S. N. Misra, “A novel LASSO – TLBO – SVR hybrid model for an efficient portfolio construction,†North Am. J. Econ. Financ., vol. 55, p. 101350, Jan. 2021, doi: 10.1016/j.najef.2020.101350.

B. van Opheusden, L. Acerbi, and W. J. Ma, “Unbiased and efficient loglikelihood estimation with inverse binomial sampling,†PLoS Comput. Biol., vol. 16, no. 12 December, p. e1008483, Dec. 2020, doi: 10.1371/journal.pcbi.1008483.

S. Morrison, “Longest Covid case as man tests positive for 305 days ,†Evening Standard, June 23, 2021. (accessed July 06, 2021).

K. M. Bubar et al., “Model-informed COVID-19 vaccine prioritization strategies by age and serostatus,†Science (80-. )., vol. 371, no. 6532, pp. 916–921, Feb. 2021, doi: 10.1126/science.abe6959.

Y. Boum et al., “Performance and operational feasibility of antigen and antibody rapid diagnostic tests for COVID-19 in symptomatic and asymptomatic patients in Cameroon: a clinical, prospective, diagnostic accuracy study,†Lancet Infect. Dis., Mar. 2021, doi: 10.1016/S1473-3099(21)00132-8.

T. Toptan et al., “Evaluation of a SARS-CoV-2 rapid antigen test: Potential to help reduce community spread?,†J. Clin. Virol., vol. 135, p. 104713, Feb. 2021, doi: 10.1016/j.jcv.2020.104713.



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