Vaccine makers claims efficacy against Omicron variant of Covid-19

With Omicron and its sub-variants spreading rapidly across the globe, vaccine makers have started claiming efficacy of their Covid-19 vaccines against this Sars-CoV-2 variant.

On Wednesday, Russia’s Gamaleya Institute claimed that taking one shot or two shot boosters of either Sputnik Light or Sputnik V resulted in significant protection against chances of hospitalisation caused by Omicron.

The Sputnik V vaccine makers said that a study conducted by a team of Russian scientists including representatives of City Clinical Hospital and the Gamaleya National Research Center of Epidemiology and Microbiology found that Sputnik V’s efficacy against hospitalisation caused by Omicron was 97 percent after one shot booster (Sputnik Light), and 99.4 percent after two shot booster (Sputnik V) after taking two shots of Sputnik V.

For patients who had received at least one dose of Sputnik V, the efficacy was 85.9 percent. The study involved around 1000 patients in Moscow.

Meanwhile, in India a study by the Indian Council of Medical Research (ICMR) and Bharat Biotech found that a Covaxin booster dose enhances the effectiveness against Delta and the Omicron variants (BA.1.1 and BA.2). The study, which has not been peer reviewed, found antibody response, clinical observations, viral load reduction and lung disease severity after virus challenge in Syrian Hamsters.

The findings of the study have been published on Tuesday on bioRxiv, a pre-print server.

"In the Delta infection study, where we compared the protective response between the two and three-dose regimens, we could observe the advantage of the booster dose vaccination in the protection. Although the neutralising antibody levels were comparable among the groups, lung disease severity was found more reduced after the three dose vaccination,” it noted. Protective response against Omicron variants was also observed in the immunized groups of animals.

In the first week of June, Hyderabad based Biological E had said that giving a shot of its Covid19 vaccine Corbevax after two doses of Covishield or Covaxin significantly improved protection against the coronavirus.

It added that a subset of subjects evaluated for neutralizing antibodies (nAb) against the Omicron variant, the Corbevax booster shot resulted in a significant increase in the nAb titers against the Omicron variant. “After the booster dose of Corbevax, Omicron nAbs were observed in 91 percent and 75 percent of subjects who had received primary vaccination by Covishield and Covaxin respectively,” Biological E said, adding that the Corbevax booster also resulted in enhanced cellular immune response.

Serum Institute of India (SII) is getting ready to work with its US partner Novavax on an Omicron variant specific vaccine for Covid-19 that would be different from the original shot developed by the US major using the Wuhan strain of the Sars-CoV-2 virus.

The Pune-based company has also got a nod from the Indian drug regulator’s office to manufacture trial batches of this vaccine for the purpose of testing, sources indicated.

Serum Institute of India (SII) is getting ready to work with its US partner Novavax on an Omicron variant specific vaccine for Covid-19 that would be different from the original shot developed by the US major using the Wuhan strain of the Sars-CoV-2 virus.

The Pune-based company has also got a nod from the Indian drug regulator’s office to manufacture trial batches of this vaccine for the purpose of testing, sources indicated.

Earlier this week, Mumbai civic officials have confirmed three cases of BA.4 sub-variant and one case of BA.5 in the city. Omicron has been the dominant strain across the world since January, quickly replacing the Delta variant that had caused a devastating second wave in India.

Demand for precaution shots in India has been rather low with only 179,079 doses being administered among the 18-59 years population. The off take is slightly better among senior citizens who are also getting it free in government vaccination centers with 235,899 doses as of Wednesday afternoon (CoWIN).

In December, British drug major AstraZeneca had claimed that a third booster shot of the AstraZeneca-Oxford vaccine Vaxzevria (Covishield in India) significantly boosts antibody levels against the Omicron variant. Experts are of the opinion that mixing vaccine shots may give better results to boost immunity. However, the University of Oxford has supported the use of Vaxzevria as a third booster dose against Omicron.