Different groups focused on studies of multi-epitope vaccines against various TLRs. For instance, Oladipo et al. studied the TLR2, TLR3, TLR4 and TLR9, while Rafi et al. focused on TLR2 and TLR4, and Ysrafil et al. investigated TLR3, TLR4 and TLR8, as well as angiotensin-converting enzyme 2 (ACE2) as the entry receptors of SARS-CoV-2. Drawing upon the structure of the SARS-CoV-2 spike (S) glycoprotein (and nucleocapsid (N) protein and open reading frame 1a (ORF1a) protein in the case of Ysrafil et al. ), the authors tried to develop a potent multi-epitope subunit vaccine. Another interesting study was proposed by Pitaloka et al. .