In order to get the intact structures for WT/Delta RBD and antibodies, missing residues in flexible loops were modeled using SWISS-MODEL. Delta RBD model was created by PyMOL2.5 to yield K417N and E484K on the basis of 7vvs . The Delta model in our simulations have 4 mutations: K417N, L452R, T478K, and E484K.