Jombo, GTA, and AE Obiagwu. “Emerging Covid-19 Variants and Vaccine Efficacy? An Eye on the Future”. Western Journal of Medical and Biomedical Sciences 2, no. 2 (August 29, 2021): xxvii-xxxii. Accessed May 15, 2024. https://wjmbs.com.ng/index.php/wjmbs/article/view/58.