A team of researchers at the Indian Institute of Technology (IIT) Madras has shown that spike protein vaccines may be effective against multiple variants of Covid-19.
The findings suggested that the attack by selected variants -- Delta plus, Gamma, Zeta, Mink and Omicron -- may be dealt with by vaccine-induced T-cell responses despite the compromised neutralising antibodies responses.
"The efficacy of vaccines, in this case, different forms of spike protein-based vaccines, depends on whether it can trigger not only the antibody response but also the T cell response," Vani Janakiraman, Assistant Professor from the institute, said in a statement.
"Efficacy against multiple variants can be assessed by first analysing the epitope sequences of various variants for mutations and if they can effectively trigger T-cells induced in the immunisation process," Janakiraman added.
For the study, the team planned to find out what the response would be like if the post-vaccination infections were caused by a variant other than the original Wuhan strain incorporated in vaccine preparations.
In variants of SARS COV-2, there are molecular level changes to the spike protein of the virus, and these variations may include the regions of protein sequences that are recognised by T-cells called epitopes, the researchers said.
Understanding the effect of these variations on the immune response can clarify the efficacy of vaccination against the variants of SARS COV- 2, they added.
The vaccines could be considered effective against the variants if there are less mutated epitopes in their spike proteins and, if the mutated epitopes can still induce an immune response comparable to that elicited by original/native epitopes.