* Mild symptoms for those who are fully vaccinated

* Not much prevalent in children

* Cases almost equal in men and women

Severity in Covid-19 is much lesser in Omicron variant when compared to Delta variant. Those who are fully vaccinated with both the doses need not worry about this, says Dr Praveen Kulkarni, Consultant Physician & Diabetologist  of KIMS hospital. Either Non vaccinated or those who took only single dose are being hospitalized more, and ICU admissions are almost not there, he said. Delta variant has affected women more but in omicron both the numbers are the same. The omicron variant, which is rampant all over the world, is prevalent in India too. At present, 3.5 lakh daily cases are registered. Dr Praveen Kulkarni explains the origin of omicron, its spread and all.

On November 24, 2021, South Africa reported the identification of a new SARS-CoV-2 variant, B.1.1.529, to the World Health Organization (WHO). B.1.1.529 was first detected in specimens collected on November 11, 2021 in Botswana and on November 14, 2021 in South Africa.

The Omicron variant has also been detected in travel-related cases in several European countries, as well as India, Australia, Brazil, Canada, Hong Kong, Israel, Japan, Nigeria, Norway, Sweden, and the United Kingdom.

On November 26, 2021, the Technical Advisory Group on SARS-CoV-2 Virus Evolution (TAG-VE) convened to assess B.1.1.529. The TAG-VE advised WHO that this variant should be designated as a Variant of Concern (VOC), and WHO designated B.1.1.529 as a VOC named Omicron.

The WHO classification as a variant of concern(VOC) was based on epidemiological data indicating an increase in infections in South Africa, that coincided with detection of Omicron. Omicron has many concerning spike protein substitutions, some of which are known from other variants to be associated with reduced susceptibility to available monoclonal antibody therapeutics or reduced neutralization by convalescent and vaccinee sera.

The European Center for Disease Prevention and Control also classified this variant as a VOC due to concerns “regarding immune escape and potentially increased transmissibility compared to the Delta variant.

The spike protein of the Omicron variant is characterized by at least 30 amino acid substitutions, three small deletions, and one small insertion. Notably, 15 of the 30 amino acid substitutions are in the receptor binding domain (RBD).

Transmissibility: Analysis of the changes in the spike protein indicate that the Omicron variant is likely to have increased transmission compared to the original SARS-CoV-2 virus, still more data needed.

Disease Severity:  Currently, it is unclear if infection with the Omicron variant is associated with more severe disease. Preliminary information from South Africa indicates that there are no unusual symptoms associated with Omicron variant infection, and as with other variants. some studies have shown a reduced risk of hospitalization,intensive care admission, and in hospital mortality.

Impact on Monoclonal Antibody Treatments:  Currently, there are no virus-specific data available to assess whether monoclonal antibody treatments will retain efficacy against the Omicron variant. Based on data from other variants with significantly fewer changes in the RBD, the expectation is that the Omicron variant will remain susceptible to some monoclonal antibody treatments, while others may have less potency.

Impact on Vaccine-Induced Immunity or Immunity from Previous Infection:  Currently, there are no data available to assess the ability of sera from vaccinated persons or those with previous SARS-CoV-2 infection to neutralize the Omicron variant.

The spike protein is the primary target of vaccine-induced immunity. The Omicron variant contains more changes in the spike protein than have been observed in other variants, including 15 in the RBD. Based on the number of substitutions, the location of these substitutions, and data from other variants with similar spike protein substitutions, significant reductions in neutralizing activity of sera from vaccinated or previously infected individuals, which may indicate reduced protection from infection, are anticipated.

Laboratory and epidemiological studies are needed to assess the impact of the Omicron variant on vaccine effectiveness and breakthrough infections, including in individuals who have received booster doses. However, vaccination is anticipated to continue to offer protection against hospitalization and death, and vaccines continue to play a critical role in controlling the COVID-19 pandemic.