Mutation in SARS Cov2Approx Read Time: 3 min
- India has suspended all flights to and from the UK until December 31, due to concerns of a new variant of SARS-CoV-2, that is spreading & growing rapidly in UK.
- Several other countries, too, have suspended UK flights and imposed travel restrictions.
- Covid-19 case rates have almost doubled in London over the past week, with almost 60% of these infections due to the new strain (variant).
About: Mutations in a virus
- When a virus replicates or makes copies of itself, it sometimes changes a little bit. These changes are called mutations. The virus with the new mutation(s) is called a variant of the original virus.
- Most changes generally do not have an impact on the virus’ properties.
- However, depending on where the changes are located in the virus genetic material, and how these changes affect the virus’ shape or properties, some changes could potentiallyimpact how the virus behaves and spreads.
- Occasionally, the changes result in a virus variant that adapts to its environment in a better way compared to the original virus.
- In such cases, it can become dominant in a specific environment. This process of selection of successful variants is called viral evolution and this is a natural process all viruses go through.
Rate of change in viruses:
- Some viruses change quickly, while other viruses change slowly.
- SARS-CoV-2, the virus which causes COVID-19, changes more slowly than others viruses such as HIV or influenza viruses.
- This is partly due to the fact that SARS-CoV-2 has an internal mechanism which corrects mistakes when it makes copies of itself.
New variant of SARS-CoV-2:
- The new variant is being referred to as VUI (Variant Under Investigation) 202012/01, or the B.1.1.7 lineage.
- This new variant has, for now, been most prominently noticed in the UK.
- Samples from Denmark and Australia collected in November 2020 are similar to the new UK variant. This most likely indicates that international spread has occurred, although the extent of the spread is unknown.
- The new variant was identified by COVID-19 Genomics UK (COG-UK), a consortium that analyses genome sequencing data from the UK. COG-UK is the largest contributor to the global Covid-19 database GISAID.
- The variant is the result of multiple mutations in the spike protein of the novel coronavirusSARS-CoV-2, as well as mutations in other genomic regions of the RNA virus.
- One mutation called N501Y changes the most important part of the spike protein, known as the “receptor-binding domain”. This is where the spike protein makes first contact with the surface of the human body’s cells.
- This is an indication that the changes may, theoretically, result in the virus becoming more infectious and may lead to a quicker spread of Covid between people.
- The evidence shows that infection rates in geographical areas where this particular strain (variant) has been circulating have increased faster than expected.
- However, the British health authority has said that currently they do not have evidence to suggest that the variant will cause more severe disease or mortality.
Implications of the mutation in SARS Cov2:
- Based on preliminary analysis the new variant could potentially increase the reproduction number of the disease by up to 0.93.
- Reproduction number or R0 is used to describe the contagiousness of the disease, which gives the number of persons infected by every positive case.
- When the R0 is less than one, not every infected person spreads the virus to other people. With an R0 above one, the country witnesses exponential growth in cases.
- If the change in the virus is so significant that the virus is different from the one that vaccines are designed to deal with, it may influence how well vaccines and diagnostic tests work.
- However, currently there is no evidence that the vaccine being developed for Covid-19 would not protect people against the new variant. Further, laboratory work will be conducted to understand this.
Earlier mutations in SARS-CoV-2:
- For SARS-CoV-2, there are currently around 4,000 mutations in the spike protein. The variant D614G was earlier the dominant strain because it spread very easily.
- Another strain that originated in Spanish farmworkers, 20A. EU1, spread rapidly across Europe in summer.
- It is difficult to predict if any particular mutation is important when it first emerges, as new mutations keep occurring continuously.
- Since the start of the outbreak, WHO has been working with a global network of expert laboratories around the world to support testing and better understanding of the SARS-CoV-2 virus that causes COVID-19.
- Within WHO’s global laboratory network, it has established a dedicated SARS-CoV-2 Evolution Working Group, which is working to detect new mutations early and assess their possible impact on the virus itself and on tests, treatments and vaccines.
Efforts to contain the spread of the variant in India
- Over the past two weeks, 4,200 people have come to Delhi from the UK. A list of these people and their contact numbers has been prepared and district-level teams will be contacting each person and tests will be conducted.
- Samples tested positive through RT-PCR will be preserved for 14 days to find out the genome sequencing of Covid-19.
- Positive patients would be sent to institutional quarantine and negative patients will be advised to isolate at home for seven days.