
Keywords: رگرسیون لجستیک چند طبقه; tOPV; trivalent oral polio vaccine; PV3; poliovirus serotype 3; WHO; World Health Organization; MLR; multilevel logistic regression; SD; standard deviation; CI; confidence interval; OR; odds ratio; OPV; oral poliovirus vaccine; mOPV3; serotype-3 monovalen