CME INDIA Presentation by Dr. Shashank Heda, Founder and Chief Executive, CovidRxExchange (CovidRxExchange is a Global Non-profit Organization registered with the US Govt. Exempt under IRS code 501 C (3), relentlessly working since March 2020, disseminating expertise and insight in the medical care of Covid), Dallas, Texas, US. Email: firstname.lastname@example.org; email@example.com.
1. Emerging data indicating that Omicron, at this time in the pandemic, is less pathogenic than Delta.
2. Omicron outcome may have positive implications in terms of decreasing the Covid-19 burden of severe disease.
“The increase in Delta variant neutralisation in individuals infected with Omicron may result in decreased ability of Delta to re-infect those individuals. If Omicron does prove to be less pathogenic, then this may show that the course of the pandemic has shifted – Omicron will take over, at least for now, and we may have less disruption of our lives.” – Prof Alex Sigal (Africa Health Research Institute, Durban, South Africa and School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Durban, South Africa).
- Omicron infection enhances neutralising immunity against Delta (Collated by CovidRxExchange).
- Infection with the SARS-CoV-2 Omicron variant creates a neutralising immune response against the Delta variant.
- The research team enrolled 15 previously vaccinated and unvaccinated people who were infected with the Omicron variant into the study. They used plasma, a blood product which contains antibodies, from the participants to test the ability of the antibodies to control both Omicron and Delta in the lab – a so-called ‘neutralisation’ test (Collated by CovidRxExchange). They measured this close to when the participants had symptoms, and again around two weeks later.
- The results showed the development of antibody response to Omicron, with neutralisation increasing 14-fold over this time (Collated by CovidRxExchange). However, the team also observed that the participants developed some enhanced immunity against the Delta variant, with Delta neutralisation increasing 4.4-fold. The researchers also show that vaccinated participants were able to mount a better neutralising response against Delta, while the response in unvaccinated participants was more variable.
- “The increase in Delta variant neutralisation in individuals infected with Omicron (Collated by CovidRxExchange) may result in decreased ability of Delta to re-infect those individuals,” said Prof Sigal. “If Omicron does prove to be less pathogenic, then this may show that the course of the pandemic has shifted – Omicron will take over, at least for now, and we may have less disruption of our lives.
- This is a Big News. I shared evidence to support the contention that Omicron infection may actually prevent infection from the dreaded Delta.
- To clarify further, there is no evidence to state that Omicron may herald an end of Epidemic or other variants.
CME INDIA Learning Points
- In South Africa Omicron infections led to a lower incidence of severe disease relative to other variants.
- That Delta and Omicron will interact is still unclear.
- Whole world is excited that Omicron will curtail the spread of Delta by eliciting a neutralizing immune response against Delta in people infected by Omicron
- Alex Sigal, Khadija Khan, Sandile Cele et al isolated Omicron virus without the R346K mutation from an infection in South Africa. This virus had similar neutralization escape.
- They neutralized this isolate with plasma from the blood of 15 participants enrolled during the Omicron infection wave in South Africa, with each participant having a confirmed diagnosis of SARS-CoV-2 by 60 qPCR.
- They used a live virus neutralization assay and calculated the focus reduction neutralization test (FRNT50) value, the inverse of the plasma dilution required for 50% 62 reduction in infection foci.
- It is well known that the ability of one variant to elicit immunity which can cross-neutralize another variant varies by variant.
- Immunity elicited by Delta infection does not cross-neutralize Beta virus and Beta elicited immunity does not cross-neutralize Delta well.
- This is the first study showing that Omicron can displace the Delta variant.
- So, it can elicit immunity which neutralizes Delta – making re-infection with Delta less likely.
- This finding becomes a big news indeed as Omicron escapes neutralizing immunity elicited by Delta and therefore may re-infect Delta infected individuals.
- If Omicron (less pathogenic) displaces mighty Delta, then the incidence of Covid-19 severe disease would be reduced and the next year – 2022 – will be less disruptive to India too.
CME INDIA Tail Piece
2.Omicron infection enhances neutralizing immunity against the Delta variant
Khadija Khan, Farina Karim, Sandile Cele, et al.medRxiv 2021.12.27.21268439; doi: https://doi.org/10.1101/2021.12.27.21268439
3. Cele, S. et al. Escape of SARS-CoV-2 501Y.V2 from neutralization by convalescent plasma. Nature 593, 142-146, doi:10.1038/s41586-021-03471-w (2021).
4. Moyo-Gwete, T. et al. Cross-Reactive Neutralizing Antibody Responses Elicited by SARS-CoV261 2 501Y.V2 (B.1.351). N Engl J Med 384, 2161-2163, doi:10.1056/NEJMc2104192 (2021). 262 11
5. Greaney, A. J. et al. A SARS-CoV-2 variant elicits an antibody response with a shifted immunodominance hierarchy. bioRxiv, 2021.2010.2012.464114, 264 doi:10.1101/2021.10.12.464114 (2021).
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