I have used chi-square/odds-ratios to show that the prevalence of the target protein is significantly reduced in both the vaccinated and non-vaccinated individuals, compared with baseline. I've also done a chi-square between the vaccinated and non-vaccinated individuals to show no significant change.

My question is - The prevalence change for the vaccinated group is -20% (from 23% down to 3%), and the prevalence change for the non-vaccinated group is -18% (from 23% to 5%). What statistical method can I use to test if this change is not/significantly different for the two groups?

Thanks,

G