V1 | V2 | V3 | V4 | |
V1 | 0 | l1∂∂y+l2∂∂Φ | l3∂∂x+a4∂∂Φ | l5∂∂Φ |
V2 | -(l1∂∂y+l2∂∂Φ) | 0 | l6∂∂Φ | 0 |
V3 | -(l3∂∂x+l4∂∂Φ) | -l6∂∂Φ | 0 | 0 |
V4 | −l5∂∂Φ | -l6∂∂Φ | 0 | 0 |
The currently ongoing COVID-19 outbreak remains a global health concern. Understanding the transmission modes of COVID-19 can help develop more effective prevention and control strategies. In this study, we devise a two-strain nonlinear dynamical model with the purpose to shed light on the effect of multiple factors on the outbreak of the epidemic. Our targeted model incorporates the simultaneous transmission of the mutant strain and wild strain, environmental transmission and the implementation of vaccination, in the context of shortage of essential medical resources. By using the nonlinear least-square method, the model is validated based on the daily case data of the second COVID-19 wave in India, which has triggered a heavy load of confirmed cases. We present the formula for the effective reproduction number and give an estimate of it over the time. By conducting Latin Hyperbolic Sampling (LHS), evaluating the partial rank correlation coefficients (PRCCs) and other sensitivity analysis, we have found that increasing the transmission probability in contact with the mutant strain, the proportion of infecteds with mutant strain, the ratio of probability of the vaccinated individuals being infected, or the indirect transmission rate, all could aggravate the outbreak by raising the total number of deaths. We also found that increasing the recovery rate of those infecteds with mutant strain while decreasing their disease-induced death rate, or raising the vaccination rate, both could alleviate the outbreak by reducing the deaths. Our results demonstrate that reducing the prevalence of the mutant strain, improving the clearance of the virus in the environment, and strengthening the ability to treat infected individuals are critical to mitigate and control the spread of COVID-19, especially in the resource-constrained regions.
Citation: Aili Wang, Xueying Zhang, Rong Yan, Duo Bai, Jingmin He. Evaluating the impact of multiple factors on the control of COVID-19 epidemic: A modelling analysis using India as a case study[J]. Mathematical Biosciences and Engineering, 2023, 20(4): 6237-6272. doi: 10.3934/mbe.2023269
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The currently ongoing COVID-19 outbreak remains a global health concern. Understanding the transmission modes of COVID-19 can help develop more effective prevention and control strategies. In this study, we devise a two-strain nonlinear dynamical model with the purpose to shed light on the effect of multiple factors on the outbreak of the epidemic. Our targeted model incorporates the simultaneous transmission of the mutant strain and wild strain, environmental transmission and the implementation of vaccination, in the context of shortage of essential medical resources. By using the nonlinear least-square method, the model is validated based on the daily case data of the second COVID-19 wave in India, which has triggered a heavy load of confirmed cases. We present the formula for the effective reproduction number and give an estimate of it over the time. By conducting Latin Hyperbolic Sampling (LHS), evaluating the partial rank correlation coefficients (PRCCs) and other sensitivity analysis, we have found that increasing the transmission probability in contact with the mutant strain, the proportion of infecteds with mutant strain, the ratio of probability of the vaccinated individuals being infected, or the indirect transmission rate, all could aggravate the outbreak by raising the total number of deaths. We also found that increasing the recovery rate of those infecteds with mutant strain while decreasing their disease-induced death rate, or raising the vaccination rate, both could alleviate the outbreak by reducing the deaths. Our results demonstrate that reducing the prevalence of the mutant strain, improving the clearance of the virus in the environment, and strengthening the ability to treat infected individuals are critical to mitigate and control the spread of COVID-19, especially in the resource-constrained regions.
Many physical phenomena, in the fields of sound and electrical waves, heat transfer, mechanics, and optics can be described through partial differential equations. Therefore, we can say that the study of mathematical physics depends primarily on the study of partial differential equations. During previous decades, many methods were developed to reduce and solve partial differential equations, including Symmetry method [1,2,3,4], scattering transformation [5], Tanh method [6], the homogeneous balance method [7], Aboodh transform decomposition method [8], (G′/G, 1/G)-expansion method [9], Exp-function method [10], Generalized He's Exp-function method [11], Kudryashov method [12], and Generalized Kudryashov method [13]. Consider the nonlinear (2+1)-dimensional Date-Jimbo-Kashiwara-Miwa (DJKM) equation [14,15] in the following form:
Φxxxxy+4ΦxxyΦx+2ΦxxxΦy+6ΦxyΦxx+Φyyy−2Φxxt=0, | (1) |
where Φ=Φ(x,y,t). DJKM describes the wave diffusion of physical-quantity, and it has certain applications in plasma physics [16,17]. This equation was presented by Jimbo and Miwa as second formulas for Kadomtsev-Petviashvili hierarchy.
There is a wealth of literature related to this governing equation such as: Bibi and Ahmad [14] who employed the symmetry method to reduce the governing equation to another equation of lower order and obtained its exact solutions. The exp(−ϕ(ξ))-Expansion Method was utilized by Sajid and Akram [14] for obtaining traveling wave solutions for Eq (1). Halder et al. [18] used the Lie symmetry analysis and singularity method to study one type of the governing equation. Wazwaz [19] studied the integrability of this equation and obtained multiple soliton solutions by using Painlevé analysis and Hirota's method. Akram et al. [16] applied the extended direct algebraic method to obtain exact solutions for the governing equation.
The previous literature led us to determine the study of the governing equation to apply the Lie symmetry method and the Generalized Kudryashov method. Our main objective of this paper is to convert the governing equation to several distinct ordinary differential equations (ODE). We then solve the resulting ODEs to obtain exact and novel wave solutions for the governing equation. As a result, we can show the dynamic behavior of wave solutions in 2-D and 3-D plots.
In this part, the Lie symmetry method [20,21,22] is used to deduce the similarity reductions for the governing equation, so the one-parameter Lie symmetry of infinitesimal variables is shown as follows:
t∗=t+εA(t,x,y,Φ)+o(ε2), x∗=x+εB(t,x,y,Φ)+o(ε2),y∗=y+εC(t,x,y,Φ)+o(ε2), Φ∗=Φ+εE(t,x,y,Φ)+o(ε2), | (2) |
where ε is the one parameter Lie group, A,B,C and E are infinitesimal variables and t,x and y are independent variables of the function Φ.
The vector generator χ is related to the above-mentioned group transformations which can be written as the following expression:
χ=A∂∂t+B∂∂x+C∂∂y+E∂∂Φ, | (3) |
when the following invariance condition is satisfied:
Γ(3)(Δ)=0, | (4) |
where Δ represents Eq (1) and Γ(3) is the third order prolongation[23,24] of the operator V
Γ(3)=χ+E[x]∂∂Φx+E[y]∂∂Φy+E[xy]∂∂Φxy+E[xxx]∂∂Φxxx+E[xxy]∂∂Φxxy+E[xxt]∂Φ∂Φxxt+E[xxy]∂∂Φxxy+E[xxxy]∂∂Φxxxy+E[yyy]∂∂Φyyy, | (5) |
where the components E[x],E[xx],E[xyy],E[y],E[xy].... can be determined from the following expressions:
E[x]=DxE−ΦtDxA−ΦxDxB−ΦyDxC,E[y]=DyE−ΦtDyA−ΦxDyB−ΦyDyC, E[xx]=DxE[x]−ΦxtDxA−ΦxxDxB−ΦxyDxC, E[xy]=DyE[x]−ΦxtDyA−ΦxxDyB−ΦxyDyC, E[yy]=DyE[y]−ΦxtDyA−ΦxxDyB−ΦxyDyC,E[xxxy]=DyE[xxx]−ΦxxxtDyA−ΦxxxxDyB−ΦxxxyDyC. | (6) |
Substituting (1) into Eq (4), yields an identity components Ax,Axx,Bt,Bx,.... and adding the coefficients of Φx,x,t, Φy,y,y, ... and equating them to zero, then the infinitesimals A,B,C and E are obtained from the following equations:
Ax=Ay=AΦ=0, |
By=BΦ=0,Bx=14At, |
Cx=BΦ=0, Cz=12At, |
Ex=−12Ct, EΦ=−14At, Ey=−12Bt. | (7) |
solving the system of Eq (7), we get
A=g1(t), B=14g′1x+g3(t), C=12g′1y+g2(t), E=−14g′1Φ−14xyg′′1−yg′2−12xg′3+g4(t). | (8) |
The vector field operator V of Eq (8) can be presented as
V=V1(c1)+V2(c2)+V3(c3)+V4(c4), | (9) |
where
V1=g1(t)(∂∂t+14x∂∂x+12y∂∂y−14Φ∂∂Φ)−14xyg′′1∂∂Φ,V2=g2(t)∂∂y−yα′2∂∂Φ, V3=g3(t)∂∂x−12g′3∂∂Φ, V4=g4(t)∂∂Φ. | (10) |
The Lie-bracket [Vi,Vj]=ViVj−VjVi is used for obtaining the commutator relations which are shown in Table 1, where
l1=g1g′2−12g2g′1, l2=−14(g′2g′1+2g1g′′2−g2g′′1)x,l3=g1g′3−14g3g′1, l4=−14(g′3g′1+4g1g′′3−g3g′′1)y,l5=14(4g1g′4+g4g′1), l6=−12(2g2g′3−g3g′2). | (11) |
V1 | V2 | V3 | V4 | |
V1 | 0 | l1∂∂y+l2∂∂Φ | l3∂∂x+a4∂∂Φ | l5∂∂Φ |
V2 | -(l1∂∂y+l2∂∂Φ) | 0 | l6∂∂Φ | 0 |
V3 | -(l3∂∂x+l4∂∂Φ) | -l6∂∂Φ | 0 | 0 |
V4 | −l5∂∂Φ | -l6∂∂Φ | 0 | 0 |
To obtain new independent variables, we utilize the characteristic equation as follows:
dtA(t,x,y,Φ)=dxB(t,x,y,Φ)=dyC(t,x,y,Φ)=dΦE(t,x,y,Φ). | (12) |
Case I. Using V1 where g1(t)=t2, Eq (12) takes the following form:
dtt2=dx12tx=dyty=dΦ−12tΦ. | (13) |
The similarity solution of Eq (1) takes the form
Φ(t,x,y)=1√tF(ζ,η)−xy2t, | (14) |
where ζ=x√t,η=yt. Substituting Φ in Eq (1) we get
Fηηη+6FζζFζη+2FζζζFη+4FζζηFζ+Fζζζζη=0. | (15) |
The ordinary differential equations of Eq (15) take the following experssion:
h3F′′′(θ)+6k3hF′′2(θ)+6k3hF′′′(θ)F′(θ)+k4hF′′′′′(θ)=0, | (16) |
where θ=kζ+hη.
To obtain the exact solution for Eq (16), we utilize generalized Kudryashov method (GKM) [11], given as follows:
F(θ)=A0+m∑i=1Ai(1+ϕ(θ))i, | (17) |
where ϕ(θ) is the solution for the following Ricati equation ϕ′(θ)=A+Bϕ(θ)+Cϕ2(θ). For simplicity, we take i=1 and substitute Eq (17) into Eq (16) then to obtain
h=±√4AC−B2k2, A1=2k(C−B+A), k and A0 are arbitrary constant. | (18) |
Substituting Eq (18) into Eqs (14) and (17), the exact solutions of Eq (1) can be expressed as
Set 1. A≠0,B≠0,C≠0.
Φ(t,x,y)=1√t(A0+2k(C−B+A)[−B2C+√4AC−B22Ctan(12(√4AC−B2θ))+1])−xy2t, | (19) |
where θ=kx√t+√4AC−B2k2yt.
Set 2. A=−12,B=0,C=−12.
Φ(t,x,y)=1√t(A0+−2kcot(θ)±csc(θ)+1)−xy2t, | (20) |
where θ=kx√t+2k2yt.
Case II. Substituting V1 in Eq (12) where g1(t)=t, then Eq (12) is expressed as follows:
dtt=dx14x=dy12y=dΦ−14Φ. | (21) |
Then the invariants are presented by ζ=xt14,η=yt12 and Φ(t,x,y)=1t14F(ζ,η). Further Eq (1) is reduced to the following form:
32Fζζ+12ζFζζζ+ηFηηη+Fηηη+6FζζFζη+4FζFζζη+2FζζζFη+Fζζζζη=0. | (22) |
For reducing Eq (22) to ODE we have two subcases:
Subcase (a). Using the scaling transformation in Eq (22)
F=eϵ −F, ζ=eϵ1 −ζ, η=eϵ2 η. | (23) |
Substituting from Eq (23) into Eq (22) we have 2ϵ1=ϵ2=−2ϵ.
The characteristic is given as
2dζζ=dηη=−2dFF. | (24) |
The invariant variables can be written as
θ=ζ2η, f=1ζ2F(θ). | (25) |
The ODE of Eq (22) is provided by
−θ2f′′′−6f′′−6θf′−48θf′′2−48θff′−48f′f′′′−16f′f′′′−80θf′′′−60f′′′−16θ2f′′′′′=0. | (26) |
To obtain the exact solutions of Eq (26), we suppose that the solution of Eq (26) has the form
f(θ)=A0+n∑j=1Ajθj. | (27) |
For simplicity, we take j=2, substitute Eq (27) into Eq (26), then the closed form solution of Eq (1) takes the expression
Φ(x,y)=A0+A1xy−116x3y2, | (28) |
where A0 and A1 are arbitrary constant.
Subcase (b). Utilizing symmetry method for Eq (22), we obtained the infinitesimals of Eq (22) as follows:
τ=12c1ζ+c2, β=c1η+c3, ψ=−12(F+xy)c1−14ηc2−14ζc3. | (29) |
The vector field of Eq (22) can take the form
χ=χ1(c1)+χ2(c2)+χ3(c3), | (30) |
where
χ1=12ζ∂∂ζ+∂∂η−12(F+xy)∂∂F, χ2=∂∂ζ−14η∂∂F, χ3=∂∂η−14ζ∂∂F. | (31) |
Using χ2+wχ3, the characteristic equation is yielded
dζ1=dηw=dF−14η−w4ζ. | (32) |
The similarity solution for Eq (22) takes the form
F(ζ,η)=f(θ)−14ηζ, where θ=η−wζ. | (33) |
The reduced ODE can take the expression
f′′′(θ)−6w3f′′2(θ)−6w3f′(θ)f′′′(θ)+w4f′′′′′(θ)=0. | (34) |
Utilizing GKM in the previous case, the closed-form solution of Eq (34) is shown as
f(θ)=A0+A11+ϕ(θ)+A2(1+ϕ(θ))2. | (35) |
Substituting Eq (35) into Eq (34), collecting the coefficients of derivative ϕ(θ) and solving the algebraic equations, we obtain the values of A0 and A1
A1=−2(A+C−B)(4AC−B2)14, w=1(4AC−B2)14, A0, A2 are arbitrary. | (36) |
Set 1. A≠0,B≠0,C≠0.
Φ(t,x,y)=1t14(A0+A1[−B2C+√4AC−B22Ctan(12(√4AC−B2θ))+1]+A2[−B2C+√4AC−B22Ctan(12(√4AC−B2θ))+1]2)−y4√txt14, | (37) |
where A1=−2(A+C−B)(4AC−B2)14,θ=y√t+1(4AC−B2)14xt14.
Set 2. A=12,B=0,C=12.
Φ(t,x,y)=1t14(A0+A1csc(θ)−cot(θ)+1+A2(csc(θ)−cot(θ)+1)2)−y4√txt14, | (38) |
where A1=−12,θ=y√t+xt14.
Cases III. Using wV2,V3,V4 where g2(t),g3(t),g4(t) are constants, we get
dt0=dxw=dy1=dΨ1. | (39) |
Using Eq (39), we obtain the invariant solutions
Φ(t,x,y)=F(ζ,η)+y, where ζ=t, η=x−wy. | (40) |
Substituting Eq (40) into Eq (1) we get
2Fζηη+w3Fηηη+6wF2ηη+6wFηηηFη−2Fηηη+wFηηηηη=0. | (41) |
Utilizing transformation θ=kζ+hη, Eq (41) is reduced to the next equation
h2(2k+hw3−2h)F′′′(θ)+6wh4F′′2(θ)+6wh4F′′′(θ)F′(θ)+wh5F′′′′′(θ)=0. | (42) |
The exact solutions of Eq (42) can be deduced by applying GKM in the previous method. Substituting Eq (17) into Eq (42) at i=1 and collecting the coefficient of derivative ϕ(θ), then equating this equations to zero, this equations is solved and the values of A0,A1,w,h and k are obtained as
k=12(4h2wAC+4−w3−h2wB2), A1=2(C+A−B)h,A0,h,w are arbitrary. | (43) |
The closed-form solutions of Eq (1) can be expressed as
Set 1. A≠0,B≠0,C=0.
Φ(t,x,y)=A0+2(A−B)h−AB+1Bexp(B θ)+1+y, | (44) |
where k=12(4−w3−h2wB2),θ=kt+h(x−wy).
Set 2. A=0,B≠0,C≠0.
Φ(t,x,y)=A0+2(C−B)h (Cexp(B θ)−1)Bexp(B θ)+Cexp(B θ)−1+y, | (45) |
where k=12(4−w3−h2wB2),θ=kt+h(x−wy).
Cases IV. Utilizing wV2,V3, where α2(t),α3(t) are constant, we obtain
dt0=dx1=dyw=dΨ0. | (46) |
Using Eq (46), we obtain the invariant solutions
Φ(t,x,y)=F(ζ,η), where ζ=t, η=x−wy. | (47) |
Substituting Eq (47) into Eq (1) we get
2Fζηη+w3Fηηη++6wF2ηη+6wFηηηFη+wFηηηηη=0. | (48) |
Taking the transformation θ=kζ+hη, Eq (48) is reduced to the form
h2(2k+hw3−2h)F′′′(θ)+6wh4F′′2(θ)+6wh4F′′′(θ)F′(θ)+wh5F′′′′′(θ)=0. | (49) |
The coveted exact solution of Eq (49) is given. Hence, by using Eq (17) in Eq (49), the solution for Eq (1) is provided as
Set 1. A≠0,B≠0,C≠0.
Φ(t,x,y)=A0+2(C+A−B)h[−B2C+√4AC−B22Ctan(12(√4AC−B2θ))+1], | (50) |
where k=12(4h2wAC+4−w3−h2wB2),θ=kt+h(x−wy).
Set 2. A=12,B=0,C=−12.
Φ(t,x,y)=A0−12hcoth(θ)±csch(θ)+1, | (51) |
where k=12(−h2w+4−w3),θ=kt+h(x−wy).
In this section, we explain the dynamic behavior of the obtained solutions in Eqs (19), (20), (28), (37), (38), (44), (45) and compare these results with previous literatures.
The physical behavior of the solutions is illustrated in three-dimensional and two-dimensional forms. The solutions include trigonometric functions, hyperbolic functions, and expansion functions. The Maple software was used to review the solutions as follows:
In Figure 1, presents wave solution of Eq (19) in 3-D and 2-D shapes with perfect numerical values of A0=5,k=0.1,A=3,C=2,B=−1 at y = 1.
In Figure 2, the solution of Eq (28) shows the behavior of a single wave and it is presented through 3-D and 2-D graphs. The constants are chosen as follows: A0=1,A2=1,k=0.1,A=3,C=2,B=3 when y=1.
Figure 3 shows doubly soliton of Eq (37) in 3-D and 2-D shapes with perfect choice for values of A0=0,A1=1.
Figure 4 depicts the view anti-kink wave solution of Eq (44) in 3-D and 2-D graphs with a suitable choice of values A0=3,w=−1,h=−3,A=2,C=0,B=1 with y=1.
In Figure 5, the solution of Eq (45) represents a kink wave solution in 3-D and 2-D plots with perfect simulation of the values A0=1,h=2,w=1,z=1,A=0,C=−3,B=1 at y=1.
The authors in [13] used the symmetry method and obtained a subcase from our infinitesimals. Then, they reduced the governing equation to one reduction case, but we obtained five reduction cases.
The authors in [14] used two different traveling wave methods to obtain exact solutions. However, they reduced the governing equation through an algebraic transformation. When comparing these solutions with our obtained solutions, it turned out that our solutions are novel solutions and show different physical behavior from other solutions.
In this paper, we applied the Lie symmetry method to obtain infinitesimals and vector fields. This led to reduce the governing equation to a new form of partial differential equations (PDEs). Then, by utilizing the symmetry method again and similarity transformation: the new form of PDEs has been converted instead of reduced to five different ODEs. The general exact wave solutions are obtained by using GKM. These solutions are represented in 2-D and 3-D graphs to show the physical properties of the solutions.
The authors declare that they have not used Artificial Intelligence (AI) tools in the creation of this article.
The author (A. A. Gaber) would like to thank the Deanship of Scientific Research of Majmaah University for supporting this work under Project Number (R-2024-947).
The authors declare no conflicts of interest.
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1. | Ying Wang, Yunxi Guo, Several Dynamic Properties for the gkCH Equation, 2022, 14, 2073-8994, 1772, 10.3390/sym14091772 | |
2. | Wenbing Wu, Uniqueness and stability analysis to a system of nonlocal partial differential equations related to an epidemic model, 2023, 0170-4214, 10.1002/mma.8990 | |
3. | Ying Wang, Yunxi Guo, Persistence properties and blow-up phenomena for a generalized Camassa–Holm equation, 2023, 2023, 1687-2770, 10.1186/s13661-023-01738-x |
V1 | V2 | V3 | V4 | |
V1 | 0 | l1∂∂y+l2∂∂Φ | l3∂∂x+a4∂∂Φ | l5∂∂Φ |
V2 | -(l1∂∂y+l2∂∂Φ) | 0 | l6∂∂Φ | 0 |
V3 | -(l3∂∂x+l4∂∂Φ) | -l6∂∂Φ | 0 | 0 |
V4 | −l5∂∂Φ | -l6∂∂Φ | 0 | 0 |