DNA Explainer: How effective are the available COVID-19 vaccines?

The Pfizer vaccine showed an efficacy of 95% at preventing symptomatic COVID-19 infection after two doses. The vaccine appeared to be more or less equally protective across age groups and racial and ethnic groups.

'Quite effective' against variants of concern (VOCs) first detected in the UK (B117), South African (B1351), and Brazil (P1).

(Image Source: Reuters)

The Moderna vaccine was 94.1% effective at preventing symptomatic COVID-19 after the second dose. The vaccine's efficacy appeared to be slightly lower in people 65 and older. The vaccine appeared to be equally effective across different ethnic and racial groups.

'Quite effective' against B117, B1351, and P1.

(Image Source: Reuters)

The Covishield vaccine is made from a weakened version of a common cold virus (known as an adenovirus) from chimpanzees. It has been modified to look more like coronavirus although it can't cause illness. When the vaccine is injected into a patient, it prompts the immune system to start making antibodies and primes it to attack any coronavirus infection.

Effective against B117, and P1, but not much against B1351.

(Image Source: Reuters)

The Johnson and Johnson one-dose vaccine was shown to be 66% protective against moderate to severe COVID infections overall from 28 days after injection, though there was variability based on geographic locations. The vaccine was 72% protective in the United States, 66% protective in South America, and 57% protective in South Africa.

Effective against all three, but less so against B1351, and P1.

(Image Source: Reuters)

Russia's Sputnik V has been deemed to be safe and works in a way similar to the Oxford-AstraZeneca jab which is being made in India as Covishield. Sputnik V gives around 91% protection against COVID-19, late-stage trial results published in The Lancet revealed.

Clinical trials were largely done in Russia last year, so performance against VOCs not known.

(Image Source: Reuters)

2-dose inactivated virus vaccine with 50% efficacy. A study in Brazil showed 50% efficacy against P1.

(Image Source: Reuters)

2-dose protein-based vaccine with an overall efficacy of 89%. Effective against B117 and B1351.

(Image Source: Reuters)

Covaxin is an inactivated vaccine which means that it is made up of killed coronaviruses, making it safe to be injected into the body. When administered, immune cells can still recognise the dead virus, prompting the immune system to make antibodies against the pandemic virus.

Effective against wild-type virus and B117.

(Image Source: IANS)