The incidence of a disease is analyzed using Poisson regression and the log link function GLM.

Explanation variables are age, area and sex, all categorical variables.
Age is 4 levels, area is 4 levels, and sex is 2 levels.
Incidence rate = number/population is an object of interest, so
The objective variable is number and population is used as an offset term.

Age group "2",
Area group "3",
Sex group "1"
Is to find an estimate of the incidence of those who fall into and the 95% confidence interval.

As a Poisson regression GLM,

model = glm (number ~ offset (log (population)) + age + area + sex,
                       family = poisson, data = lung)

And made a model.

The estimated incidence for those who fall into the above group is

exp (model $coefficients [1] #Intercept
   + model $coefficients [2] # age2
   + model $coefficients [6] # area3
   + model $coefficients [8]) # sex1

I think you can find it in the above code

I don't know what to do to find this 95% confidence interval.
I think you use confint.
I would be grateful if you could tell me.