COVID vaccines: Here's how they stack up in efficacy terms

Moderna: It is 94.1 per cent effective at preventing symptomatic infection in people. In clinical trials, the vaccine appeared to have high efficacy among people of diverse age, sex, race, and ethnicity categories and among persons with underlying medical conditions.

Pfizer-BioNTech: The vaccine offers 95 per cent efficacy in preventing COVID-19 in those without previous infection. According to a research report, the vaccine was equally effective across a range of people and variables, including gender, race, ethnicity, age, and body mass index (BMI)—or presence of other medical conditions. The vaccine was 100 per cent effective at preventing severe disease in clinical trials.

Sputnik V: According to late-stage trial results published in The Lancet, Russia's Sputnik V coronavirus vaccine offers around 92 per cent protection.

Johnson & Johnson: In the US, it offers 72 per cent overall efficiency and 86 per cent efficiency against severe diseases.

Covaxin: On Wednesday, Bharat Biotech said Covaxin was 81 per cent effective in preventing COVID and can work against the UK variant of the virus as it revealed Phase III trial results for a vaccine that was cleared in January.