Initially, a sample of SARS-CoV-2 was isolated by India's National Institute of Virology and used to grow large quantities of the virus using vero cells.

[2][10][11] The vaccine is produced with Bharat Biotech's in-house vero cell manufacturing platform[12] that has the capacity to deliver about 300 million doses.

[20] In May 2021, Haffkine Bio-Pharmaceutical Corporation Limited of Haffkine Institute entered into a memorandum of understanding (MoU) with Bharat Biotech and announced that the production of Covaxin by them will commence after obtaining support from the Maharashtra state government and approval from the Indian government[21] whereas Indian Immunologicals Limited (IIL) has signed a commercial agreement with Bharat Biotech for producing the drug substance, a critical component of the vaccine[22] Bharat Immunologicals and Biologicals Corporation (BIBCOL) will also manufacture the vaccine.

[27] A total of 12 sites were selected by the Indian Council for Medical Research for Phase I and II randomised, double-blind and placebo-controlled clinical trials of vaccine candidate.

[45] In June 2021, Bharat Biotech announced the start of phase IV trials to evaluate the vaccine's real-world effectiveness.

[53] In April 2021, the Indian Council of Medical Research reported that the vaccine has shown promising results in neutralising lineage B.1.617.

[54][55] In May 2021, a joint investigation by the scientists of the National Institute of Virology, found the vaccine effective in neutralising the Zeta variant or lineage P.2 (previously known as B.1.1.28).

[56] In June 2021, a group of researchers at the National Institute of Virology (NIV) India, collected sera from recovered patients and people who had received the Covaxin.

[59][11] On 6 December 2020, Bharat Biotech applied to the Drugs Controller General of India (DCGI), seeking emergency use authorisation.

[64] This emergency approval, granted without considering Phase III trial data concerning efficacy and safety, drew widespread criticism.

[74] On 31 March, the Brazilian health regulator Anvisa rejected Bharat Biotech's application for supplying Covaxin in the country due to non-compliance with manufacturing norms.

[75] On 4 June, Anvisa approved exceptional imports of Covaxin, imposing conditions that restrict it mainly to healthy adults and limiting it to just 1% of the country's population to manage the risks through control and supervision of side effects.

Anvisa cited as main concerns the incomplete phase III study, a short 45-day follow-up, which should be 60 days to meet the international consensus, and a novel imidazoquinoline adjuvant that may increase the chance of developing an autoimmune disease.

[76][77][78] On 30 June, Brazilian regulators suspended the deal and an investigation was opened into it by federal prosecutors to probe accusations of irregularity.