A heat-stable Covid vaccine that is being developed in India and does not need cold chain storage has generated a strong antibody response against coronavirus variants, including Delta and Omicron, according to a study on mice. The vaccine candidate, by the Indian Institute of Science (IISc) in Bengaluru and biotech start-up company Mynvax, uses a part of the viral spike protein called the receptor-binding domain (RBD), which allows the virus to connect with the host cell to infect it, said a statement here.