Covid-19 vaccine candidate, Covaxin, being developed by Bharat Biotech, has shown `durable’ immunity in phase I and II trails.
As per pre-peer reviewed published findings, second phase trials of the Covid-19 had shown long term antibody response.
Covaxin showed long-term antibody and T-cell memory responses (three months after vaccination) in phase 1 volunteers, tolerable safety outcomes with enhanced humoral and cell-mediated immune reactions in the Phase 2 study.
"Based on follow-up data from the phase 1 trial, at day 104 (three months after the second dose), despite a marginal expected decline in neutralising antibody titres, BBV152 (Covaxin) has exhibited the potential to provide durable humoral immunity and cell-mediated immunity,’’ the research paper said.
Based on the phase 2 trial findings, a phase 3 efficacy trial is now being carried out in 25,800 volunteers.
The results reported here do not permit efficacy assessments. The evaluation of safety outcomes requires extensive phase 3 clinical trials, the study said.
``We were unable to assess other immune responses (binding antibody and cell-mediated responses) of convalescent serum due to the limited quantity. No additional data on the severity of disease from symptomatic individuals were obtained,’’ the paper said.
The study population lacked ethnic diversity, further underscoring the importance of evaluating vaccine candidate in other populations. ``Longitudinal follow-up is important and is ongoing,’’ it added.