(Down to Earth: News)
Dec 3: Omicron: What we know so far – https://www.downtoearth.org.in/news/health/omicron-what-we-know-so-far-80525
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Omicron: What we know so far
Context: The World Health Organisation’s (WHO) classification of ‘Omicron’ as a variant of concern (VOC) of the novel coronavirus at the onset of the pandemic’s third year has given rise to more uncertainties even as normalcy seemed about to return.
- South Africa — where Omicron was first isolated November 24, 2021 — has already declared its fourth wave: County after county have been recording a dangerous spike in cases.
- The new variant has been detected in at least 30 countries, with India reporting its first two cases December 2.
- Since the detection of Omicron, South Africa’s daily caseload has gone up to 11,500 December 3 (from 200 mid-November). The Gauteng province, where the infection was first found, reported a 360 per cent rise in cases between November 21 and 28. Hospitalisation increased 300 per cent and deaths by 17.65 per cent in four weeks.
The Omicron variant
- Has 50 mutations overall, 32 alone on the spike protein — the protruding knobs on the outside of the virus that help it stick to cells and gain entry. This is the protein that all three vaccines currently available in the United States use to induce protective antibodies.
- Delta, in comparison, has nine mutations.
- The larger number of mutations in Omicron may increase its transmissibility and its ability to dodge immunity.
- The latest VOC has overtaken Delta to become the most dominant in the country. More than 70 per cent of all virus genomes sequenced in November were of the new variant, according to South Africa’s National Institute for Communicable Diseases (NICD).
- Omicron is infecting those earlier infected by other variants, NICD South Africa has said. The behaviour and characteristics of the variant are yet to be clinically studied, but preliminary reports revealed an ability to evade immunity developed either through natural infection or vaccination.
The Current Issue
- Vaccines are still believed to be protecting against severe infections or death caused by COVID-19. Studies are being conducted to understand if Omicron can evade immunity. However, work on variant-specific vaccines by leading manufacturers (including Pfizer Inc and Moderna Inc) is underway.
- Debates on waning immunity have gained momentum over the past week. Several studies, yet to be peer-reviewed, have claimed that antibodies decline after about five months of the second dose, thus causing breakthrough infections. Immunologists, however, have repeatedly cautioned against overreacting to such concerns.
- Immunity is currently tested through antibody tests — a metric not all accurate as the body has other reserves to fight off an infection (eg, the memory B and memory T cells).
- This part of our immune system is responsible for mustering a response against severe disease or death.
- A memory B cell produces antibodies, while a memory T cell destroys infected cells once activated. The latter remains dormant within the body for long.
- The rate at which our memory B and memory T cells decline, with regard to COVID-19 vaccines, is yet unknown. Their lifespan change based on the virus. For instance, a vaccine for measles give lifelong protection, while regular immunisation is needed for protection against the influenza virus every season.
Barring its potential to evade immunity, the Omicron variant raises concerns because of how infectious it may be. The R value — defined as how many people an infected person can spread the virus to — for the Delta variant is between 6 and 7. The current R value for Omicron is 2, but it was 1 in September when the Delta variant was dominant.
With the Omicron variant on the prowl, there is a need to increase vaccination rates.