SEIRDV model parameter fitting,,

Hi, I am studying the Covid-19 model 'SEIRDV' in which the vaccine was introduced.

I want update new 'beta'and 'u' by using lsqcurvefit, but l can't.

Here is my code. Please review this and give me advice. I am so desperate....

<SEIRDV.m>

function dydt = SEIRDV(t,y)

global beta gamma alpha sigma epsilon N u d

%S=y(1), E=y(2), I=y(3), R=y(4), D=y(5), V=y(6)

dydt= zeros(6,1);

dydt(1) = -beta*y(1)*y(2)/N - alpha*u*y(1)/N;

dydt(2) = beta*y(1)*y(2)/N - sigma*y(2);

dydt(3) = sigma*y(2) - (1-epsilon)*gamma*y(3) - epsilon*d*y(3);

dydt(4) = (1-epsilon)*gamma*y(3);

dydt(5) = epsilon*d*y(3);

dydt(6) = alpha*u*y(1)/N;

<SEIRDV_ode.m>

% initial conditions : S0 = 51732328, E0 = 424, I0 = 7457, R0 = 79880, D0 = 1580, V0 = 0

global beta gamma alpha sigma epsilon N u d

N= 51821669;

alpha = 0.761;

u = 24452;

sigma = 1/5;

epsilon = 0.143;

gamma = 1/14;

d = 1/17.7;

beta = 0.2096

[t,y] = ode45(@SEIRDV,[0,365],[51732328 424 7457 79880 1580 0]);

p= lsqcurvefit(fun,[0;0],x,y);

beta = p(1);

u = p(2);

hold on

real= xlsread('Daily Confirmed Number.xlsx');

t=0:1:441;

y=real(:,2);

real= xlsread('Daily vaccination count.xlsx');

t=0:1:70;

y=real(:,2);

plot(t,y,'o')

hold off

If this is not the way to do it, please tell me how to complete the code.

[Elon Musk]

Hi, can you please tell me what is beta gamma alpha sigma epsilon u d in your code?

Which rate is beta, gamma, alpha, sigma, epsilon?

What is u and d?