Question

Regarding COVID-19 and recent researches about it, relate its:

a) reaction rate with its infection rate (biochemical or biological prespective)

b) reaction rate and reaction order with its reproductive rate of the virus

cite your sources.

Answer 1

The Eyring’s rate process theory and free volume concept, two very popular theories in chemistry and physics fields, are employed to treat infectious disease transmissions. The susceptible individuals are assumed to move stochastically from one place to another. The virus particle transmission rate is assumed to obey the Eyring’s rate process theory and also controlled by how much free volume available in a system. The transmission process is considered to be a sequential chemical reaction, and the concentrations or fractions of four epidemiological compartments, the susceptible, the exposed, the infected, and the removed, can be derived and calculated. The obtained equations show that the basic reproduction number, R0, is not a constant, dependent on the volume fraction of virus particles, virus particle size, and virus particle packing structure, the energy barrier associated with susceptible individuals, and environment temperature. The developed models are applied to treat coronavirus disease 2019 (Covid-19) transmission and make predictions on peak time, peak infected, and R0.

A sequential chemical reaction process from the susceptible, to the exposed, the infected, and the removed in the end is proposed to describe disease transmissions. At each step, there is a chemical rate constant associated with and the fraction of each product/reactant can be easily calculated. Every step is a one-way reaction, except the last step from the infected to the removed, as some small amount of the removed could be infected again. The Eyring’s rate process theory and free volume concept continue to be used for defining rate constants. In general, our model predicts that the fraction of the infected will peak at certain time, increase with the volume fraction of virus particles, and decrease with temperature. The energy barrier for human to move has played a critical role in disease transmissions. The isolation process with a huge energy barrier for human can change the chemical reaction rate constant dramatically. The basic reproduction number is not a constant and can be computed once the parameters in the models are determined. In particular, we applied our models to treat coronavirus (Covid-19) transmission. Based on the data provided by CCDC, we predict that the infected may peak at 158 days from Jan. 21, 2020 and may take a long time, more than a year, to drop to zero, though MSIR and MSEIR models give a slightly different estimation. The data of the infected don’t match with the removed for both models: based on the infected data, the removed is predicted to be 8 and 13 times smaller than the actual reported according to MSIR and MSEIR models. If the removed data, either the recovered or the recovered plus the death, are reliable, the actual infected people is between 579488 and 941668 by Feb. 17, 2020. The basic reproduction number of coronavirus (Covid-19) is computed to be about 1.5 based on MSIR model and 3.5 based on MSEIR model

On the basis of this study, firstly we provided the proportion of severe versus common cases of the COVID-19 infection, which was approximately 1:4, the ratio of severe to mild, non-pneumonia and asymptomatic cases were 18%, 73%, 4%, and 5% respectively, the changes and prognosis of those four categories should be future observed in hospitals. 13 asymptomatic cases were the close contacts who were found by medical observation in this study. If not insulated for medical observation, they would not seek health care or visit hospital and cannot be found in the special period, and will spread to the other close contacts.15, 16 Therefore, to identify and control the non-pneumonia and asymptomatic cases are important measures to prevent transmission on the COVID-19.

The age of patients was from 6 months to 94-year-old, the majority of patients were young adults (77.4%), there was no significant difference between males and females in our study, the population was generally susceptible. The patients were mainly residents of Beijing (73.3%), while the other patients mostly came from Wuhan(20.2%). But 89.1% of the residents of Beijing had been travel to Wuhan or contacted the confirmed case in 14 days especially in the early stage of COVID-19 infection, after Feb. 1, the number of locally confirmed cases began to exceed imported cases. In this study, 133 patients from more than 20 families were infected, same as Wuhan, the infection of COVID-19 in Beijing was of clustering onset too.13, 14 Therefore, person-to-person transmission is the main route of transmission.

Source:

Infection Dynamics of Coronavirus Disease 2019 (Covid-19) Modeled with the Integration of the Eyring’s Rate Process Theory and Free Volume Concept Tian Hao 15905 Tanberry Dr., Chino Hills, CA 91709, USA (Dated: 29th February, 2020, 10:13)