The estimate of infected individuals of the 2019-Novel Coronavirus in South Korea by incoming international students from the countries of risk of 2019-Novel Coronavirus: a simulation study

Objectives: Overall, 37000 international students from the country of risk of 2019 Novel Coronavirus (COVID-19) will arrive in South Korea. The individuals from the country of risk of COVID-19 are included a home-quarantine program, but the efficacy of the program is uncertain. Methods: To estimate the possible number of infected individuals due to the large influx of international students, the deterministic compartment was modeled by different compliance of home-quarantine. Results: Our findings, under the strict compliance of quarantine for the incoming international students, indicate it is less likely to occur epidemics in South Korea. 2 Conclusion: To mitigate possible epidemics, considerable public health resources with high compliance of quarantine are needed.


Introduction
The respiratory virus has been threatened three times in South Korea since the 21st century; On 14 February 2020, Korean public health authority identified an individual of COVID-19 infection and the patient was contacted with a suspected individual who avoided the quarantine program during his period of self-quarantine. Previous literature demonstrated the effectiveness of quarantine is highly likely varied due to the individuals' daily motility patterns (4); however, the compliance of self-quarantine is still in question.
Overall, 37000 international students from China, where major Chinese cities are likely sustaining localized outbreaks (5), will join the spring semester in Seoul, Korea on March 1, 2020. Therefore, this large number of incoming young individuals departing from the Country of risk of COVID-19 is a potential threat to occur local transmission in South Korea.
. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted February 19, 2020. Here, we aimed to estimate the number of infected individuals in Seoul, Korea by different compliance of self-quarantine of those incoming international students. Our study provides evidence of the public health resources taken for the epidemic preparedness to be the best for public health authorities.

Materials and Methods
To simulate the possible epidemics, we used the deterministic compartment model of susceptibleexposed-infectious-removed (SEIR) type (see the Supplementary Appendix). We assumed that the population mixed homogenously, and there had been no COVID-19 transmission occurred in the community in South Korea.
We assumed the 0.2, 1, or 3% of the incoming international students is the pre-infectious period in which previous literature reported that asymptomatic fraction of SARS is 0.2-3% (6, 7). We also assumed that the international students would arrive in Seoul, Korea in 15 days before and  CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

(which was not certified by peer review)
The copyright holder for this preprint this version posted February 19, 2020.

Discussion
In the absence of effective vaccine and treatment of infectious disease, quarantine of suspected individuals of infection including exposed persons of infection from epidemic countries has been used as one of the mitigation strategies implemented by public health authorities (8,9). The quarantine of possibly exposed individuals of COVID-19 is an efficient public health strategy to reduce the transmission using limited public health resources because unidentified infected individuals are highly likely to be identified among the exposed individuals of infectious diseases (9). Therefore, it is crucial to estimate the number of infected individuals by the different . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

(which was not certified by peer review)
The copyright holder for this preprint this version posted February 19, 2020. . https://doi.org/10.1101/2020.02.15.20023234 doi: medRxiv preprint 5 compliance of self-quarantine to provide relevant evidence to public health authorities in order to improve the compliance of the quarantine program for the international students in advance.
In South Korea, the individuals contacted with the infected person were asked to comply with home quarantine and were monitored by the local public health workers twice a day for 14 days after contact with the infected individuals (3). The individuals who were not included in the quarantine program but experienced with any possible contact were encouraged to notify the public health authorities and able them to be quarantined. All the daily necessities have been provided to all quarantined individuals by the public health authorities to avoid possible contact with any susceptible population as the law is indicated. Therefore, the current Korean quarantine program is a very broad and large number of persons included. However, due to the lack of public health resources, the quarantine program for the incoming international students will be monitored by the education authority which has a lack of experience of the disease control. This may affect the efficacy of quarantine and the number of infected and isolated individuals as well.
Our findings indicate that it is less likely to occur epidemics in South Korea due to the incoming international students; however, the number of infected and isolated individuals increased by mid or late of March.
Our results indicate that it is less likely to occur epidemics in South Korea due to the incoming international students. However, this may consume a large number of public health resources including monitoring individuals quarantined and isolation of infected individuals.
There are several limitations to this study. First, some of the parameter including the latent period and rate of infection among contacted we used, was not identified from the COVID-19. This may affect the results. Second, we used the deterministic model which does not present a confidence interval. However, the deterministic model is a sufficient simulation method to model the dynamics of the number of infected individuals which is much smaller than the total population . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

(which was not certified by peer review)
The copyright holder for this preprint this version posted February 19, 2020. . https://doi.org/10.1101/2020.02.15.20023234 doi: medRxiv preprint 6 (10). Third, we did not consider the transmission occurred before the symptom onset and the subclinical infection.

Conclusion
As public health resources are limited, quarantine of the possibly exposed individuals of COVID-19 is crucial for public health authorities to prevent local transmission. Strict quarantine for

Conflict of interests
We declare no competing interests

Ethical approval
Not applicable . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

(which was not certified by peer review)
The copyright holder for this preprint this version posted February 19, 2020. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted February 19, 2020.  . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted February 19, 2020. . https://doi.org/10.1101/2020.02.15.20023234 doi: medRxiv preprint