Transmission of COVID-19 in the presence of single-dose and double-dose vaccines with hesitancy: mathematical modeling and optimal control analysis. - Wangari, Isaac Mwangi; Olaniyi, Samson; Lebelo, Ramoshweu S.; Okosun, Kazeem O.; Tiwari, Pankaj; Mondal, Jayanta (Frontiers in Applied Mathematics & Statistics, 2023)