Immunogenicity of the Covaxin booster dose lasts up to 12 months of vaccination despite a decline in the antibodies according to a report published in the medical journal Nature Scientific Reports. Covaxin is developed in India against SARS-Cov 2. It is an inactivated Covid 19 vaccine.
Covaxin has been widely used in India in government and private hospitals. Booster doses are now being given free by the government.
The emerging variants of SARS-Cov 2 raise concern about whether the existing vaccines will be able to protect the population. Primary doses are the first two doses for protection. A booster dose is for the vulnerable population of senior citizens, those suffering from co-morbid conditions of diabetes, hypertension, cardiovascular diseases and other long-term ailments.
Does Covaxin Booster Dose offer long-term protection?
The study was conducted in 184 subjects who were randomized 1:1 and received either a booster dose or a placebo, six months after the primary series of two doses.
They were evaluated for safety, neutralizing antibody responses against variants of concern, binding antibodies against spike protein, RBD, N proteins, and for memory T and B cell responses to demonstrate cell-mediated immunity.
The study found persistence of humoral and cell-mediated immunity up to 12 months after vaccination. This means that the cell can identify the SARS-Cov 2 virus and its variants and the body's immunity is prepared to fight it.
Dr. Krishna Ella, Chairman and Managing Director, Bharat Biotech International Limited, said, "Our team has now demonstrated that COVAXIN is a multi-epitope vaccine with antibodies against spike, RBD and N proteins. Post booster dose, it has proven to neutralize antibody responses against variants of concern and long-term protection through memory T and B cell responses. We have now achieved our goal of developing a safe and efficacious vaccine with long-term protection against a spectrum of SARS-Cov 2 variants."
Research with more participants required
More people need to be followed to understand the efficacy of vaccination. With different population groups in India, antibodies have been a challenge and it is the yardstick for protection against the disease.
With more people studied, it will give a fairly clear picture in different populations who have benefited and those who have been less impacted.