Omicron-infected show high immune response against Delta: NIV study

Omicron, first reported in South Africa in November, is now the dominant strain of covid-19 globally. Reuters

Indian virologists say their research reveals people who have contracted the Omicron variant of covid-19 — even unvaccinated individuals — have shown “substantial immune response” to other variants such as Delta.

A study by scientists at the National Institute of Virology (NIV), Pune, said that based on the high levels neutralizing antibody shown by such individuals, it can be assumed that they will not be infected with Delta and other Variant of Concern (VOCs).

Omicron, first reported in South Africa in November, is now the dominant strain of covid-19 globally and the most transmissible variant till date.

The study involved 39 individuals who were mainly returnees from the UAE, Africa, elsewher in West Asia, US and UK. Six of them were unvaccinated. They were all confirmed as Omicron positive by next generation sequencing.

The participants were grouped into three categories–breakthrough infections after two doses of Covishield vaccines (25 individuals), people who were vaccinated with Pfizer’s vaccine (eight), and unvaccinated individuals (six).

Researchers analyzed the IgG and neutralizing antibodies (NAbs) against B.1, Alpha, Beta, Delta and Omicron variants with the sera of individuals infected with Omicron.

As per government guidelines they were kept in isolation and all were asymptomatic.

“The key message is that if a person is vaccinated and gets infected by Omicron, they will not get severe disease. Secondly, those who have contracted Omicron naturally and unvaccinated or else breakthrough cases, they had good immune response (against Delta and other variants,” said Dr Pragya Yadav, Senior Scientist at NIV, Pune.

The study was conducted during January this year and is now published in the latest issue of Journal of Infection. It was funded by the Indian Council of Medical Research (ICMR). To be sure, researchers emphasize that despite the results of this study, people should not lower their guard against covid-19, and continue to take all precautions.

Since January 2022, India has seen a sudden surge in Omicron infections. According to experts, the covid-19 vaccines are still showing strong protection against severe illness and death, including against Omicron.

Top Indian experts managing the national covid-19 immunization programme are working with specialists from other countries in a global effort to devise a comprehensive training programme on vaccinology.

India started its massive covid-19 vaccination drive in January 2021. At present, all adults and children in the age group of 12-14 years are eligible for the vaccine. India is also setting up a cadre of frontline epidemiologists to counter future pandemics.

As of date, India has detected more than 49 million cases with 520,000 deaths. Under the nationwide vaccination drive, more than 1.85 billion vaccine doses have been administered so far.

The writer is on a press tour as a guest of the ministry of health and family welfare.

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