Omicron in India: ICMR study suggests Covishield booster dose to fight against emerging variants

By Team Newsable | First Published Dec 5, 2021, 7:04 PM IST

While the researchers showed that the Serum Institute-manufactured jabs could counter the Delta version and its variants, they also emphasised the need for extra safeguards.

A recent study conducted by an ICMR team proposed using the Covishield COVID-19 vaccination as a booster dose, noticing a decrease in effectiveness against Delta variants. The news comes as there is rising worry about the Omicron version of COVID-19 and requests for booster doses to be made available in India. While the researchers showed that the Serum Institute-manufactured jabs could counter the Delta version and its variants, they also emphasised the need for extra safeguards.

According to an excerpt from the paper's conclusions, the data imply that the Covishield vaccination could neutralise Delta derivatives and avoid severe illness and mortality among breakthrough cases. A booster dose vaccination of COVID-19 naive vaccinees would result in a protective immune response to combat developing SARS-CoV-2 mutations.

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The paper has yet to be peer-reviewed after being released on the bioRxiv preprint platform. The researchers looked at three types of blood samples: those who had been fully vaccinated but had never been exposed to COVID-19, those who had been fully vaccinated after recovering from COVID-19 infection, and those who had become infected after being fully vaccinated.

While neutralisation against the Delta and AY.1 variants was lowered in all three groups, they found a 27.3-fold drop (the largest) in neutralising antibody levels against the Delta variant in completely vaccinated people who had never been infected.

The key explanation for this, according to the study, is that people who have never been exposed to COVID-19 have a limited time survival of plasmablast cells following immunisation. Memory B cells are activated in those infected with COVID-19 (before or after injection), resulting in a greater level of immunological response. Given the evidence that vaccinations lose effectiveness over time, many countries, including the United States, have already authorised the use of booster doses for all people.

Also Read | Amid Omicron threat, India's genome scientists recommend booster shot for those above 40

A Lancet research published earlier this week found that six distinct COVID-19 boosters were safe and produced a significant immunological response in persons who had previously received a two-dose course of AstraZeneca or Pfizer vaccinations. Covishield, by the way, is the Oxford-AstraZeneca vaccine manufactured in India. The Lancet study found that the AstraZeneca, Pfizer-BioNTech, Novavax, Janssen, Moderna, Valneva, and Curevac vaccines were safe to use as a third dose increased spike protein immunogenicity following two initial doses of the AstraZeneca vaccine. The researchers investigated the immune response after 28 days and will do additional studies at three months and one year after patients had their boosters.

The third dosage was administered 10-12 weeks following the initial two-dose course to randomised study participants. However, it should be emphasised that various persons (in different nations) received their dosages at different times. India began its COVID-19 immunisation campaign over a year ago and has administered around 1.26 billion doses of three vaccinations (Covishield, Covaxin, and Sputnik V).

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