Covaxin is an inactivated whole virion vaccine developed by Bharat Biotech, an Indian biotechnology company. This vaccine was created in collaboration with the Indian Council of Medical Research (ICMR) and the National Institute of Virology (NIV). Its primary purpose is to provide protection against COVID-19.
The Science Behind Covaxin
Covaxin utilizes a well-established vaccine platform known as inactivated virus technology. This method involves taking a sample of the SARS-CoV-2 virus and chemically treating it to render it inactive.
The inactivated virus, though unable to infect, retains its structural integrity. When administered as a vaccine, this “dead” virus acts as an antigen, presenting the immune system with various viral proteins. The vaccine also includes adjuvants, such as aluminum hydroxide gel and a TLR 7/8 agonist, to further enhance the immune response. This allows the immune system to recognize the whole virus and develop a broad defensive reaction, including the production of antibodies and memory cells.
Clinical Trial Findings and Safety
Covaxin underwent a series of clinical trials, including Phase 1, 2, and 3 studies, to evaluate its efficacy, safety, and immunogenicity. The Phase 1 trial enrolled 375 subjects and demonstrated excellent safety data with minimal reactogenicity. Phase 2 trials, involving 380 participants, also reported no serious adverse events.
The large-scale Phase 3 clinical trial involved 25,800 participants across 25 sites in India. This trial showed Covaxin to be 77.8% effective against symptomatic COVID-19. The vaccine demonstrated a higher efficacy of 93.4% against severe symptomatic COVID-19, which significantly reduces the need for hospitalization. Efficacy against asymptomatic COVID-19 was found to be 63.6%.
Common side effects reported across trials were generally mild and temporary, similar to those experienced with other COVID-19 vaccines. These included:
Fever
Headaches
Irritability
Pain or swelling at the injection site
Fatigue
Body aches
Nausea
Vomiting
Chills
While serious adverse events were rare, some observational studies have noted occurrences of conditions like viral upper respiratory tract infections, skin disorders, nervous system issues, and in very rare cases, stroke and Guillain-Barre Syndrome. Bharat Biotech has stated that numerous studies published in peer-reviewed journals confirm Covaxin’s excellent safety record.
Regulatory Status and Global Reach
Covaxin has received regulatory approvals, contributing to its global deployment. The World Health Organization (WHO) granted Covaxin an Emergency Use Listing (EUL) on November 3, 2021. This WHO validation facilitates the vaccine’s acceptance and distribution worldwide, enabling countries to expedite their own regulatory approvals.
Beyond the WHO EUL, Covaxin has also been approved by national regulatory bodies. By January 31, 2022, Covaxin had received emergency use authorization in 13 countries. Countries that have approved Covaxin include Iran, Zimbabwe, Nepal, Mexico, Philippines, Guatemala, Nicaragua, Guyana, Venezuela, and Botswana. Its approvals and EUL status highlight Covaxin’s role in global vaccination efforts, particularly in low and middle-income countries due to its favorable storage requirements.