THE SOLUTION OF A MATHEMATICAL MODEL FOR COVID-19 TRANSMISSION AND VACCINATION IN NIGERIA BY USING A DIFFERENTIAL TRANSFORMATION METHOD. FJS [Internet]. 2022 Nov. 2 [cited 2025 Sep. 11];6(5):50-6. Available from: http://www.fjsadmin.fudutsinma.edu.ng/index.php/fjs/article/view/1089