What are SARS-CoV-2 variants?
As an infected cell builds new coronaviruses, it occasionally makes tiny copying errors. These are called mutations. A group of coronaviruses that shares the same inherited set of distinctive mutations is called a variant. Currently the World Health Organization (WHO) has given following list of VOC (Variants of Concern) and VOi (Variants of Interest).
Variants of concern
• Omicron (B.1.1.529), identified in southern Africa in November 2021.
• Delta (B.1.617.2), which emerged in India in late 2020 and spread around the world.
• Gamma (P.1), which emerged in Brazil in late 2020.
• Beta (B.1.351), which emerged in South Africa in early 2020.
Variants of interest
• Mu (B.1.621), which emerged in Colombia in early 2021.
• Lambda (C.37), which emerged in Peru in late 2020.
• Alpha <B.i.i.7>. which merged in Britain in late 2020.
Why is it called Omicron?
The WHO has been using Greek letters to refer to the most widely prevalent coronavirus variants, which otherwise carry long scientific names. In picking a name for the newest variant of SARS-CoV-2 that emerged in South Africa 'Omicron' (B.1.1.529) was used.
The WHO has skipped two letters of the Greek alphabet, i.e. Nu and Xi - because Nu is too easily confounded with 'new' and XI was not used because it is a common surname and WHO best practices avoids
causing offence to any cultural, social,
national, regional, professional or ethnic groups.
Earlier they were named after the country from where they were first reported, 'UK variant', 'Indian variant', 'South African variant'. To remove the connection with specific countries, which was triggering name-calling and blame game, the WHO decided on a new naming system using Greek letters. The variant that earlier used to be referred as the 'Indian' thus got the name Delta, while the one being associated with the UK was named Alpha and so on.
Is Omicron a super variant?
It is a super variant because it has the super mutated "S" gene and thereby has potentially increased transmissibility. This suggests the Omicron variant may be more transmissible than the Delta variant, but it may cause less serious illness.
What are its symptoms?
Preliminary reports suggest that people infected with the Omicron variant have similar symptoms to other variants of SARS-CoV-2. There are hearsay reports of patients having no loss of taste or smell, however these should be interpreted with caution until more data is available.
Are the risk factors of Omicron the same as other COVID variants?
Risk factors are similar to other COVID variants. Studies reported that older people, people with comorbidities, those who are immune-compromised, obese individuals are at a higher risk of having a more severe illness.
Will it cause severe illness?
As per WHO, initial reported infections were among university students - younger individuals who tend to have milder
disease - but understanding the level of severity of the Omicron variant will take days to several weeks. All variants of COVID-19, including the Delta variant that is dominant worldwide, can cause severe disease or death in particular for the most vulnerable people and thus prevention is always key.
How is Omicron different from other variants?
Variants emerge through changes or errors, called mutations, in the sequence of the virus's genome, which is the virus's set of genetic instructions. The Omicron variant has significantly more mutations than other variants in its S gene - the gene that encodes the virus's spike protein, which is the key that provides the virus with access to our cells. Omicron has accumulated 50 mutations, including 32 mutations in the S gene.
The Alpha variant has nine mutations in its S gene, and Delta has between nine and thirteen mutations. It is too early to tell what to make of the Omicron variant.
Because proteins are made of chains of amino acids, mutations in the S gene will lead to amino acid substitutions that cause changes in the spike protein.
The number of amino acid substitutions in Omicron's spike protein, and their overlap with those seen in the other VOC and VOi makes this variant's spike protein look supercharged.
Will vaccination or prior infedion proted against Omicron?
The WHO is working with technical partners to understand the potential impact of this variant and if existing vaccines will prove effective against it. Vaccines remain critical to reducing the severity of the disease, hospitalisation and death.
Preliminary evidence suggests there may be an increased risk of re-infection with Omicron (i.e., people who have previously had COVID-19 could become re-infected more easily with Omicron), as compared to other variants of concern, but information is limited.
In light of many reports that vaccine-induced (or natural infection) neutralising antibodies wane with time, many countries, are rushing to administer booster shots and increase vaccination coverage to protect their population against a possible resurgence.
Can the currently used diagnostic method detect Omicron?
As per WHO, the widely used PCR tests continue to detect infection. Studies are on-going to determine whether there is any impact on other types of tests, including rapid antigen detection tests.
What is the effectiveness of current treatments for Omicron variant?
Corticosteroids and lL-6 Receptor Blockers will still be effective for managing patients with severe COVID-19. Other treatments will be assessed to see if they are still as effective given the changes to parts of the virus in the Omicron variant.
What precautions should be taken against Omicron?
The most effective steps individuals can take to reduce the spread of the Omicron or any variant is to keep a physical distance of at least 1 meter from others, wear a well-fitting 3-layer cotton mask, open windows to improve ventilation, avoid poorly ventilated or crowded spaces, keep hands clean, cough or sneeze into a bent elbow or tissue and get vaccinated.
Will there be third wave with increasing Omicron cases?
According to reports, a double variant third wave caused by delta and Omicron variants is expected but the severity is expected to be mild. The Omicron variant is not seen to have caused severe infection. Although the Delta variant could cause severe symptoms, a large number of people have been vaccinated so the severity of infection will be mild. So we can expect the hospitalisation to be lower in the possible third wave.
Dr Shweta Deshmukh is a Consulting Physician.
