UNS – The mathematics expert of Universitas Sebelas Maret (UNS) Surakarta, Dr. Sutanto stated that the spread of Novel Coronavirus (2019-nCov) or known as Wuhan Corona Virus, China, has entered the dangerous level. This virus has spread to other cities in China and even several other countries. This can be seen from WHO data that China’s population infected by the virus has increased very rapidly.
“There is a mathematics model for every event, including the spread of disease. The mathematics model for this event is the S-I-R Model (Susceptible-Infected-Recovery). From the daily data, especially on the number of infected persons, the number of deaths and recovery from the Coronavirus; it can be concluded that the Coronavirus is the type of virus that spread rapidly. Based on the data from WHO (downloaded from Corona Virus Tracker App), the graphic of the Coronavirus spread (from the number of infected persons at each time interval) is in exponential form (Graphic 1). This shows that this virus is dangerous. Even if we see from Graphic 2, the Coronavirus spread rate is higher than SARS,” stated Dr. Sutanto in his office, Friday (14/2/2020).
The exponential graph almost reaches the “S” shape in graph 1, in which the number of infected persons is around 45 k, even though there have been significant efforts to slow down the contact between the infected persons and the healthy population. Maybe because of the widespread of Coronavirus in Mainland China, the virus is increasingly hard to detect. Thus, the graph has not moved into the “S” curve and new infection cases are detected with a fairly large number.
Different from SARS, the graphic has peaked up with the number of 8000 infected cases. This means there are no new cases of SARS infection. However, for the Coronavirus in Wuhan, the graph is still exponential with a high infection rate.
Graphic 1. Number of infected persons in China and other countries
Graphic 2. Comparison between the number of people infected with Coronavirus and SARS
Dr. Sutanto analyzed based on the mathematics model, the Coronavirus cases can be divided int three phases (S-I-R). There are three statuses of the Wuhan population in each time interval: Susceptible, Infected, Recovery. Thus, the number of populations in the Susceptible, Infected, Recovery in Wuhan will keep changing in each time interval. Mathematically, Wuhan will be clean from the Coronavirus when the number of infected persons reaches zero and this is the big work, when will the number of infected persons reach zero?
To reach zero, two stages must be passed: first, reaching the S curve suppress the rate of contact between the infected and the healthy population. Second, treating infected people to recovery. Mathematically, the model is divided into three phases:
In the first phase, the susceptible status in which people with a weak immune system will be easily infected by the Coronavirus. Those who are in the first phase are expected to stay indoors, do not leave the city or the country to avoid Coronavirus infection. Therefore, the interaction or contact rate of Coronavirus spread can be inhibited.
From the first phase, the population might enter the second phase; the infectious people’s status. From the susceptible phase, someone can be infected because they have direct contact with the infected person. In the infectious phase, the medical team will work hard to reach a high recovery rate. The Chinese government has constructed a special hospital for treating Coronavirus patients to avoid infection on other patients. Not only that, it is necessary to quarantine both healthy and sick to reduce the rate of contact between the two. Even though with these efforts, there are casualties and high death rates.
The third phase is Recovered. In this phase, people who do not die from the infection are declared as cured need recovery to not infected with the virus again. Therefore, the third cycle of the status can be illustrated in the graphic 3 below:
Graphic 3. The proportion of Susceptible-Infected and Recovery
From the graph above, the proportion of infected persons reached 60% of the Susceptible population, then successfully treated so it decreases, or the infected person status changed into recovered (or healthy again).
“From the WHO data, even though the proportion of infected persons is around 0.85%, but the contact rate of the infected person is the very high and low recovery rate. If not addressed immediately, the number of infected persons will keep increasing,” he stated.
Therefore, the step taken by the Chinese government by isolation Wuhan to suppress the spread of the Coronavirus is correct. Then building a special hospital to take care of the infected population, quarantine the healthy and recovered population to avoid infection, and other steps taken by other countries to evacuate their citizen from Wuhan. For example, Indonesia evacuated its citizens from Wuhan and conduct 14 days quarantine to see if the evacuated people have the Coronavirus. This is because the incubation period of the virus is 14 days.
Lastly, the information and knowledge of the Coronavirus spread are very important. Given the many cases we see in viral videos: “There are people who do not know that they are infected and get a sudden death. This is very dangerous because before dying the person must have made contact with several people. So that everybody has to be careful and do not mess with the Coronavirus. Obey the rules if you have to do quarantine then do it, and more importantly implement a healthy lifestyle,” he concluded. Humas UNS
