Sanjeev Kumar Patro

News Highlights

  • Omicron has switched its route of entry into human cells. This is likely to influence Omicron spread and the types of cells it can hijack.

Odisha looks very vulnerable to Omicron! The new variant is found to be giving two hoots even to an individual who has taken the double dose quota. Only one with a booster dose can duck the Omicron but with a big rider.

Because, in as many as 9 districts, only around one-third of the population is fully vaccinated (means received 2 doses), and in 15 others, not even half of the population is fully vaccinated. In the remaining 6, more than half are fully immunised, with Khordha district inoculating 70 percent of the population. 

Significantly, it's Khordha district that is topping the daily caseload Covid Chart in the State. Here is a big food for thought for those who abdicate social vaccine post taking Covaxin or Covishield.

As per the University of Glasgow Centre for Virus Research, the combined inference of laboratory experiments and real-world infection data had been the following.

  1. In laboratory tests, Omicron is largely unaffected by the antibodies provided by two doses of COVID-19 vaccine, but responses are improved by a third dose booster.
  2. Importantly, this is confirmed by analysis of real-world infection data; Omicron escape immunity from two vaccine doses, but three doses restore good levels of protection.
  3. The work also provides evidence that Omicron has switched its route of entry into human cells. This is likely to influence Omicron spread and the types of cells it can hijack.

Explaining Point Number 3

As per scientist Joe Grove at Glasgow Centre For Virus Research, SARS-CoV-2 can enter cells via two routes, both routes require spike activation by proteases ( are enzymes in the host that break down the protein). He further elaborated it.

  • Route 1: Cell surface fusion, triggered by TMPRRS2

  • What is TMPRRS2?

  • TMPRSS2 is an endothelial cell (means the cell layer that lines the cavities of heart, blood and lymph vessels to thoracic (lung region)) surface protein that is involved in the viral entry and spread of coronaviruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – the virus that causes COVID19. Blocking TMPRSS2 could potentially be an effective clinical therapy for COVID-19.

  • Route 2: endosomal fusion, triggered by cathepsins (are also enzymes that degrades or dissolves the protein). (Omicron is taking this route)

As per scientist Grove, "Protection against Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) associated disease (COVID-19) is currently reliant on a range of vaccine technologies that induce immunity to the spike protein of the virus."

He further added, "Delta (B.1.617.2) was responsible for significant waves of infections associated with an increase in reproduction number (R0). The secret behind the increased R0 is the variant harboured mutations at position 681, which is associated with enhanced cell entry."

But Omicron has undertaken such mutations that not only increased its cell-binding affinity vis-a-vis Delta but has also developed immune evasive capability.

The Glasgow Centre for Virus Research, therefore, concluded that the Omicron variant evades neutralisation by sera obtained from people vaccinated with 1 or 2 doses of vaccine, especially when antibody titres are waning.

It then added that Indicative studies have shown that 3 doses of Wuhan-strain based vaccines may provide only partial protection from infection with this variant.

Here Lies The Big Catch - Are Covishield, Covaxin booster dose efficient against Omicron?

If one goes by the Glasgow Centre for Virus Research study findings, then both the AstraZeneca (or its Indian equivalent Covishield) and desi vaccine Covaxin contain the Wuhan strain.

Covishield: As per SII data, developed by the University of Oxford and AstraZeneca. The vaccine works by delivering the genetic code of the SARS-CoV-2 (Wuhan Virus) spike protein to the body’s cell.

But in Omicron, the spike protein code stands changed. And as a consequence, the vaccine failed to detect the new mutant, the CVR study claimed.

Covaxin: As per Bharat Biotech data, the ingredients of  COVAXIN contains 6µg (microgram) of whole-virion inactivated SARS-CoV-2 (Wuhan virus) antigen.

And as per CVR findings, since the Omicron has undergone mutations in the Spike protein, it can evade the vaccine-induced immune response from the host.