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Preliminary phase 3 data suggests India’s inactivated vaccine, Covaxin, protects well against symptomatic COVID-19

Initial Phase 3 results indicate that India’s vaccine Covaxin (BBV152) – an inactivated SARS-CoV-2 vaccine – had an interim efficacy of ~81% in preventing symptomatic COVID-19. More details can be found in this press release.

An earlier preprint (more details below) indicates Covaxin neutralizes the SARS-CoV-2 variant B.1.1.7 (the UK-detected variant).

  • The trial in India has 25,800 participants (age 18-98) and includes 2433 aged 60+, with 4,500 who are reported to have co-morbidities (i.e. such that may increase the risk of severe COVID-19).
  • The primary endpoint is PCR-confirmed symptomatic COVID-19 (14 days post dose 2) in previously non-exposed individiuals.
  • Their initial interim analysis is based on 43 cases (36 in placebo group), 2nd interim planned at 87 cases, final at 130 cases.

India already started using Covaxin & AstraZeneca in early January (2021) & have so far inoculated 16 million, as reported in the New York Times

Covaxin reported to neutralize the variant B.1.1.7

Preprint data (posted late January) indicates that Covaxin neutralizes B.1.1.7 (VOC / VUI-202012/01).

This was observed in a plaque reduction neutralization assay (the green is the UK variant – by sequencing said to have been confirmed to contain all B.1.1.7 mutations).



Phase 1 data for Covaxin in the Lancet Infectious Diseases

Recent phase 1 data has indicated that Covaxin is safe & induces a robust immune response.

There was a very low frequency of reported side effects: Local pain, headache, fatigue, fever, & nausea/vomiting were the most common, and were only reported from about 2-5%. Similar to after AstraZeneca’s & J&J’s vaccine (see also the overview I wrote, here), these side effects were reportedly more common after dose 1 compared with after the 2nd dose.

The observed rate of seroconversion was ~83-93%. The definition of seroconversion was here a greater than four-fold increase in antibody titre, after vaccination, compared with values seen before vaccination.


As seen above, the phase 1 data indicated that antibody titres generated after vaccination with Covax were similar to those seen in convalescent sera (i.e. from people who have previously had COVID-19, shown on the far right). In contrast, e.g. Moderna has been found to induce far higher antibody levels (here measured as titres) – see this thread for such data.

A brief comparison with another inactivated vaccine, Sinovac’s Coronavac, can be found here.

Here’s a Twitter thread with basically the same information as above.