Mathematical modelling and optimal cost-effective control of COVID-19 transmission dynamics S. Olaniyi, O. S. Obabiyi, K. O. Okosun, A. T. Oladipo and S. O. Adewale Eur. Phys. J. Plus, 135 11 (2020) 938 Published online: 25 November 2020 DOI: 10.1140/epjp/s13360-020-00954-z