Even as the calls for India to announce booster shots for the vulnerable groups in view of the Omicron variant outbreak are getting louder, researchers are unsure how effective such jabs might be in combatting the new variant.
While some studies suggest that specific vaccines are able to curb the spread of Omicron Covid-19 variant, some have suggested vaccine cocktails and alternative therapies to stem the outbreak.
According to a report by the International New York Times, a growing body of preliminary research suggests the Covid-19 vaccines used in most of the world offer almost no defence against infection by the highly contagious Omicron variant.
All vaccines still seem to provide a significant degree of protection against serious illness from Omicron, which is the most crucial goal. But only the Pfizer and Moderna shots, when reinforced by a booster, appear to have initial success at stopping infections, and these vaccines are unavailable to most countries.
The report suggested that the other shots — including those by AstraZeneca, Johnson & Johnson and vaccines manufactured in China and Russia — do little to nothing to stop the spread of Omicron. And because most countries have built their inoculation programmes around these vaccines, the gap may impact the direction of the pandemic.
However, All India Institute of Medical Sciences director Randeep Guleria believes that existing Covid-19 vaccines can be tweaked to offer protection against newer variants of the SARS-CoV-2 virus.
The Pfizer and Moderna shots use the new mRNA technology, which has consistently offered the best protection against infection from all variants so far. All of the other vaccines are based on older methods of triggering an immune response.
Meanwhile, virologist Shahid Jameel said that the Centre needs to formulate a policy for booster dose, on the grounds that Covishield might not be ideal for usage as a booster.
"This vaccine is made using a whole chimp virus with a few genes deleted and the spike gene of Covid virus inserted in it. So this virus, besides making the Covid virus protein, it makes several of its own proteins. The immune system looks at any foreign protein to be the same so it will raise antibodies and T-cells to both the Covid protein as well as to the chimp virus proteins. Since the chimp virus proteins are many more in number compared to just one spike protein, as you give more and more of it, preferential boosting will happen of the chimp virus proteins and that's not what you want. What you want is spike responses," he said.
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