How India's five vaccines fare against the Covid-19 Delta variant

The Delta variant is known to be more transmissible and severe than the original virus detected in Wuhan

The Delta variant of Covid-19 is sweeping different parts of the world, including the US which is now registering the same level of daily cases as its previous peak due to the more transmissible strain of SARS-CoV-2. The Delta variant, which has now been detected in 135 countries in the world, led to fresh curbs in China and a rise in cases across the UK.

India granted emergency approval to Johnson & Johnson's single-shot vaccine, and now has five vaccines to fight the virus. Scientists have pondered the vaccines' efficacy against the Delta variant, which caused the deadly second wave in India in April and May.

Here's a look at how India's vaccines fare against the variant.

Covishield

Developed by Serum Institute of India, Pune, the AstraZeneca-Oxford vaccine, or Covishield as it is known in India, seems to perform well against the variant. In a study conducted in July 2021, two doses of Covishield showed 63 per cent effiicacy against the Delta variant.

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According to a study by Public Health England, two doses of Covishield were effective in preventing hospitalisation in patients of Delta variant.

Bharat Biotech's Covaxin

Bharat Biotech conducted a trial that revealed that Covaxin is 65.2 per cent effective against the Delta variant. "In the Phase 3 trial conducted by Bharat Biotech, subjects vaccinated with Covaxin achieved greater protection against emerging B.1.617.2 (delta) and B.1.351 (beta) variants than those who had previous natural infections. Results showed an efficacy rate of 65.2 per cent," the company said in a statement.

Sputnik V

Russia's Sputnik V vaccine against Covid-19 is around 90 per cent effective against the highly contagious Delta variant of coronavirus.

The shot, which Russia has actively marketed abroad, was previously found by researchers to be almost 92 per cent effective against the original strain of coronavirus.

Denis Logunov, deputy director of Moscow's Gamaleya Institute which developed Sputnik V, said the Delta variant efficacy figure was calculated based on digital medical and vaccine records, the RIA news agency reported.

Moderna

Moderna Inc. said its vaccine produced protective antibodies against the delta variant spreading in the US and many other parts of the world.

Moderna researchers tested blood samples from eight people for antibodies against versions of the spike protein from different coronavirus variants, including delta, which emerged in India. The vaccine “produced neutralizing titers against all variants tested,” the company said in a statement. The results were released on the pre-print server bioRxiv.

The protective proteins are called neutralizing antibodies because they’re capable of preventing the virus from entering cells. Compared to the quantity of antibodies produced against the main version of the virus, neutralizing antibody levels against the delta variant were reduced by 2.1-fold.

Johnson & Johnson

The Johnson & Johnson coronavirus vaccine is effective against the highly contagious Delta variant, even eight months after inoculation, the company reported.

The vaccine showed a small drop in potency against the variant, compared with its effectiveness against the original virus, the company said. But the vaccine was more effective against the Delta variant than the Beta variant, first identified in South Africa — the pattern also seen with mRNA vaccines.

Antibodies stimulated by the vaccine grow in strength over time, researchers also reported.