COVAXIN CAN HELP IN CONTROLLING THE VIRUS LOAD OF SARS-CoV-2 AND ITS VARIANTS, REDUCING DISEASE SEVERITY: STUDY
Scientists have 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 and induces memory T cells that can respond robustly against the variants. This may help in controlling the virus load and thus, reduce the disease severity.
BBV152/COVaxin vaccine is based on an Asp614Gly variant and formulated with atoll–like receptor (TLR) 7/8 agonist molecule imidazoquinoline) adsorbed to alum.
It was the first alum –imidazoquinoline adjuvanted vaccine produced in India and received emergency use authorization from WHO for use in a large population.
QUESTIONS TO BE ANSWERED
- Whether the vaccine induces immune memory,
- how long the vaccine induces memory to persist
- Whether these memory responses can sustain against the SARS –CoV-2 Variants
OBSERVATION OF THE CASE STUDY
In a multi-institutional collaboration with THSTI ,Faridabad ,AIIMS,New Delhi,ESIC Medical College,Faridabad,LNJP Hospital ,New Delhi,LJI,LA Jolla ,Dr.Nimesh Gupta and a group at the National Institute of Immunology (NII), New Delhi investigated 97 SARS-CoV-2 unexposed individuals who had received the vaccine, up to 6 months after 2-dose vaccination.
The vaccine-induced responses were compared with the immune memory in 99 individuals who recovered from mild COVID-19
The study supported under IRHPA COVID-19 special call by the science and Engineering Research Board, a statutory body of the Department of Science and Technology, found that the vaccine produces antibodies against spike, RBD, and Nucleoprotein of the virus, just like in virus infection.
However, analyses of both the binding and neutralizing antibodies revealed a reduced recognition of variants of concern like Delta (India), Beta (S.Africa) and Alpha (UK).
This study showed that the vaccine is capable of inducing memory B cells. They found this satisfying because antibodies may decline with time, but these memory B cells replenish antibodies against the virus, whenever required.
Their study provided the first ever evidence of the detailed traits of immune memory generated in humans in response to an inactivated virus vaccine
The team also found that the vaccine showed the potential of producing the Sars-CoV-2 specific T cells
Importantly and unlike antibodies, the effectiveness of the T cells was well preserved against the variants. Also, these virus-specific T cells were present in the central memory compartment and persisted up to 6months post-vaccination.
The Sars-CoV-2 variants may impact the antibody responses generated by the vaccine, however, the T cell's responses will be available to respond robustly against the variants.
