INTRODUCTION:

Coronavirus disease is an infectious disease caused by a newly discovered Coronavirus. Most people infected with the COVID-19 virus will experience mild to moderate respiratory illness and recover without requiring special treatment. COVID-19 is a respiratory disease caused by SARS-CoV-2, also known as the new Coronavirus. The discovery of a new and potentially more transmissible coronavirus variant by South African health authorities has sparked a forceful reaction across the world, with a number of countries banning travellers from several South African countries.

The World Health Organization announced Friday it has designated the newly identified Coronavirus variant, B.1.1.529, as a variant of concern, named Omicron.¹

The World Health Organization (WHO) on November 26, 2021 declared the recently discovered B.1.1.529 strain of COVID-19, first detected in South Africa, to be a variant of concern and renamed it Omicron. The classification puts Omicron into the most-troubling category of COVID-19 variants, along with the globally-dominant Delta, plus its weaker rivals Alpha, Beta and Gamma. The first known confirmed B.1.1.529 infection was from a specimen collected on November 9, 2021 from South Africa and confirmed on November 24, 2021. Omicron has also been identified in other places such as Botswana, Belgium, Hong Kong and Israel. On November 27, 2021 two more cases were detected in the United Kingdom and were linked and connected to travel in South Africa. This variant has a large number of mutations, some of which are concerning, the WHO said, pointing to the worrying characteristics. Recently, Professor Tulio de Oliveira, the director of the Centre for Epidemic Response and Innovation in South Africa, mentioned in a press conference that the Omicron variant has 50 mutations and most of the mutations (more than 30 mutations) were reported in the spike protein (S protein) of the SARS-CoV-2, which has been used as a key target for most of the available vaccines.

Moreover, the receptor-binding domain (RBD), which interacts with angiotensin-converting enzyme 2 (ACE2) to gain entry into the host cell, has 10 mutations compared to just two for the Delta variant that swept the world.²

How to pronounce Omicron:

The Cambridge Dictionary states two different English pronunciations of Omicron -"oh-MY-cron" for British English and "OH-mi-cron" for American English.

When the COVID-19 variants became a cause of concern for the general public, many people started referring to them by name of the country where they were first detected, leading to stigmatisation. To avoid this, the Greek alphabets were chosen to name the variants. WHO skipped two letters of the Greek alphabet - Nu and Xi - while naming the new variant. "'Nu' is too easily confounded with 'new,' and 'Xi' was not used because it is a common last name," WHO said in a statement.¹⁰

Classification of Omicron (B.1.1.529): SARS-CoV-2 Variant of Concern:

Based on the evidence presented indicative of a detrimental change in COVID- 19 epidemiology, the TAG-VE has advised WHO that this variant should be designated as a VOC, and the WHO has designated B.1.1.529 as a VOC, named Omicron.

As such, countries are asked to do the following:

· Enhance surveillance and sequencing efforts to better understand circulating SARS-CoV-2 variants.

· submit complete genome sequences and associated metadata to a publicly available database, such as GISAID.

· report initial cases/clusters associated with VOC infection to WHO through the IHR mechanism.

· where capacity exists and in coordination with the international community, perform field investigations and laboratory assessments to improve understanding of the potential impacts of the VOC on COVID- 19 epidemiology, severity, effectiveness of public health and social measures, diagnostic methods, immune responses, antibody neutralization, or other relevant characteristics. ³

India’s Omicron COVID count rose to 126 on Saturday after Karnataka and Kerala reported six and four cases respectively, while three more persons in Maharashtra also tested positive for the variant. According to central and state officials, omicron cases have been detected in 11 states and union territories —

Maharashtra (43), Delhi (22), Rajasthan (17) and Karnataka (14), Telangana (8),

Gujarat (7), Kerala (11), Andhra Pradesh (1), Chandigarh (1), Tamil Nadu (1) and West Bengal (1).territories — Maharashtra (43), Delhi (22), Rajasthan (17) and Karnataka (14), Telangana (8), Gujarat (7), Kerala (11), Andhra Pradesh (1), Chandigarh (1), Tamil Nadu (1) and West Bengal (1).territories — Maharashtra (43), Delhi (22), Rajasthan (17) and Karnataka (14), Telangana (8),

Gujarat (7), Kerala (11), Andhra Pradesh (1), Chandigarh (1), Tamil Nadu (1) and West Bengal (1).

The Omicron coronavirus variant has been reported in 89 countries and the number of cases is doubling in 1.5 to 3 days in areas with community transmission, the World Health Organization (WHO) said on Saturday. ⁴

Virus	Corona Virus
Variant	Omicron (B.1.1529)
Detected	South Africa
Detected on	24 Nov 2021
Variant	Variant Of Concern

⁶

Symptoms:

Most common symptoms for the new COVID Variant “Omicron” are:^6,15

· Fever

· Cough

· Tiredness

· Loss of test

· Smell

· Shortness of breath or difficulty breathing

· Fatigue

· Muscle or body aches

· Headache

· Sore throat

· Congestion or runny nose

· Nausea or vomiting:

· Diarrhea:

Chaand Nagpaul, chair of council at the BMA, said that mandatory mask wearing should be extended to all public indoor and closed settings, including for staff in the hospitality industry, such as restaurants, and beauty salons. “This addition to government measures will have minimal economic and social impact, but evidence tells us that it will help to further reduce the spread of the virus,” he said. “We only have a small window of opportunity to get this right to ensure that we don’t lose control of this new variant, which has the potential to have a devastating impact on the health service. The government must act now, or we risk seeing even more unnecessary deaths.”⁷

Lawrence Young, a virologist and professor of molecular oncology at Warwick Medical School, said, “This new variant of the covid-19 virus is very worrying. This variant carries some changes we’ve seen previously in other variants but never altogether in one virus. It also has novel mutations that we’ve not seen before.”⁷

The WHO immediately sent out guidelines and strategic plans to regional and at risk countries to deter the spread of Omicron by: a) enhancing surveillance and sequencing efforts to better understand circulating SARS-CoV-2 variants, b) submit complete genome sequences and associated metadata to a publicly available database, c) report initial cases/clusters associated with VOC infection to WHO through the IHR mechanism, and d) where capacity exists and in coordination with the international community, perform field investigations and laboratory assessments to improve understanding of the potential impacts of the VOC on COVID-19 epidemiology, severity, effectiveness of public health and social measures, diagnostic methods, immune responses, antibody neutralization, or other relevant characteristics. The effectiveness of vaccines and current treatments are still under assessment by the global researchers.However, the classical approach to combat SARSCoV-2 is still recommended by the WHO to the pandemic population.⁸

The scientific name of the Omicron variant is B.1.1.529. The COVID-19 variant of concern gets its name from the 15th letter of the Greek alphabet.¹⁰

Transmission and life-cycle of SARS-CoV-2 causing COVID-19.¹¹

Is the Omicron variant more contagious?

Omicron is spreading more quickly than other variants. Based on the information available, WHO believes it is likely that Omicron will outpace the Delta variant where there is COVID-19 transmission in the community.

However, being vaccinated and taking precautions such as avoiding crowded spaces, keeping your distance from others and wearing a mask are critical in helping to prevent the spread of COVID-19, and we know these actions have been effective against other variants.¹²

Characteristics of Selected SARS-CoV-2 Variants (Delta- Omicron):¹³

WHO Label	Delta	Omicron
Spike Protein Substitutions	T19R, (V70F), T95I, G142D, E156-, F157-, R158G, (A222V), (W258L), (K417N), L452R, T478K, D614G, P681R, D950N	A67V, del69-70, T95I, del142-144, Y145D, del211, L212I, ins214EPE, G339D, S371L, S373P, S375F, K417N, N440K, G446S, S477N, T478K, E484A, Q493R, G496S, Q498R, N501Y, Y505H, T547K, D614G, H655Y, N679K, P681H, N764K, D796Y, N856K, Q954H, N969K, L981F
Nextstrain clade	(Nextstrainexternal icon)b: 21A/S:478K	(Nextstrainexternal icon)b: 21K
First Identified	India	South Africa
Attributes	· Increased transmissibility · Nearly all lineages designated as Delta are susceptible to Emergency Use Authorization (EUA) monoclonal antibody treatments. AY.1 and AY.2 lineages are not susceptible to some monoclonal antibody treatments. · Reduction in neutralization by post-vaccination sera	· Potential increased transmissibility · Potential reduction in neutralization by some EUA monoclonal antibody treatments · Potential reduction in neutralization by post- vaccination sera

On November 30, 2021, the U.S. government SARS-CoV-2 Interagency Group (SIG) classified Omicron as a Variant of Concern (VOC). This classification was based on the following:

· Detection of cases attributed to Omicron in multiple countries, including among those without travel history.

· Transmission and replacement of the Delta variant in South Africa.

· The number and locations of substitutions in the spike protein.

· Available data for other variants with fewer substitutions in the spike protein that indicate a reduction in neutralization by sera from vaccinated or convalescent individuals.

· Available data for other variants with fewer substitutions in the spike protein that indicate reduced susceptibility to certain monoclonal antibody treatments.¹³

The SIG Variant classification scheme defines four classes of SARS- CoV-2 variants:

· Variant Being Monitored (VBM)

· Alpha (B.1.1.7 and Q lineages)

· Beta (B.1.351 and descendent lineages)

· Gamma (P.1 and descendent lineages)

· Epsilon (B.1.427 and B.1.429)

· Eta (B.1.525)

· Iota (B.1.526)

· Kappa (B.1.617.1)

· 1.617.3

· Mu (B.1.621, B.1.621.1)

· Zeta (P.2)

· Variant of Interest (VOI)

· Variant of Concern (VOC)

· Delta (B.1.617.2 and AY lineages)

· Omicron (B.1.1.529 and BA lineages)

· Variant of High Consequence (VOHC) ¹³

Figure 1 Waves of Coronavirus disease 2019 (COVID-19) epidemics recorded thus far in South Africa. (A) Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused three waves of epidemics in South Africa. The number of daily confirmed infection cases is plotted. Data were downloaded from theWorld Health Organization (WHO). (B) The number of estimated cases infected by the indicated variants of concern (VOCs) in South Africa. The original data were downloaded from global initiative on sharing all influenza data (GISAID) FIGURE daily confirmed infection cases is plotted. Data were downloaded from theWorld Health Organization (WHO). (B) The number of estimated cases infected by the indicated variants of concern (VOCs) in South Africa. The original data were downloaded from global initiative on sharing all influenza data (GISAID)¹⁴

Figure 2 Omicron is spreading faster than other variants of concern (VOCs) in South Africa. The full genomic sequences were downloaded from global initiative on sharing all influenza data (GISAID), and the original data were processed with a logistic function¹⁴

CONCLUSION:

It is also not known if new variants might evolve on the basis of Omicron in the future. But there is no doubt that the Omicron variant will not be the last variant of SARS-CoV-2. The continuous emergence of new SARS- CoV-2 variants has made the control of the COVID-19 pandemic more difficult. Opportunely, we have accumulated a lot of experiences and process to deal with the novel coronavirus and we know what we basic to do to stop the spread of virus variants.

Both the Omicron and Delta variants were investigated in this study using several computational tools and a computational saturation mutagenesis model, examining structural, sequence-driven, and dynamic changes that effect overall protein stability were examined. According to the findings of this study, large changes in the RBD region of the Omicron irregular contribute to higher binding with hACE2, which may result in a higher transmission rate when matched to the Delta variant.

REFERENCE:

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Received on 25.05.2022 Modified on 18.06.2022

Res. J. Pharmacology and Pharmacodynamics.2022;14(3):191-195.