Differential equations: how to fit my data into an ode.

Here is the EDO and data system, where I am trying to use the real data to estimate some guiding parameters.

Eq1 = S & # 39;

Eq2 = I1 & # 39;

Eq3 = R1 & # 39;


mymodel = ParametricNDSolveValue[{Eq1, Eq2, Eq3, S[0] == 5000, I1[0] == 1,
R1[0] == 0}, I1, {t, 0, 2012}, {u, k, p, alpha, beta}]realdata = {{2000, 25}, {2001, 32}, {2002, 38}, {2003, 30}, {2004,
32}, {2005, 35}, {2006, 40}, {2007, 49}, {2008, 22}, {2009,
36}, {2010, 54}, {2011, 85}};

myfit = NonlinearModelFit[realdata, mymodel[u, k, p, alpha, beta]


plotfit = Plot[myfit[myfit[myfit[myfit
plotdata = ListPlot[realdata, PlotStyle -> PointSize[0.01]];
Show[plotfit, plotdata]

It is taking forever to excite. Can you please suggest?