New Delhi: Indian scientists have found that Covaxin induces memory T-cells that can produce robust response against the variants of coronavirus. This helps in controlling the virus load and, thus, reduce the disease severity, Union Ministry of Science & Technology said.
A multi-institutional collaboration featuring THSTI (Faridabad), AIIMS New Delhi, ESIC Medical College (Faridabad), LNJP Hospital (New Delhi), LJI, LA Jolla, Dr Nimesh Gupta and group at National Institute of Immunology (NII), New Delhi, investigated 97 SARS-CoV-2 unexposed individuals who had received vaccine, up to 6 months after 2 doses.
They found that Covaxin, which is an inactivated whole-virion vaccine, induces robust immune memory to SARS-CoV-2 and variants of concern that persist for at least 6 months after vaccination.
BBV152/Covaxin vaccine is based on an Asp614Gly variant and formulated with a toll-like receptor (TLR) 7/8 agonist molecule (imidazoquinolin) adsorbed to alum.
It was the first alum-imidazoquinolin adjuvanted vaccine produced in India and received emergency use authorization from WHO for use in a large population.
The study, supported under IRHPA-COVID-19 special call by the Science and Engineering Research Board, found that the vaccine produces antibodies against Spike, RBD and Nucleoprotein of the virus, just like in virus infection. However, analyses revealed a reduced recognition of variants of concern like Delta (India), Beta (South Africa), and Alpha (UK).
The study showed the vaccine is capable of inducing memory B-cells, which can replenish antibodies against the virus, whenever required.
It’s the first evidence of detailed traits of immune memory generated in human in response to an inactivated virus vaccine.
The researchers found that the vaccine showed potential of producing SARS-CoV-2-specific T-cells. Unlike antibodies, the effectiveness of T-cells was well preserved against the variants.
Published in the journal Nature Microbiology, the study provides important knowledge for evidence-based policymaking on future application of Covaxin.
