Tuesday, 18 January, 2022
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Omicron: A Variant or a Scariant?

Dr Kanan Purkayastha

Omicron: A Variant or a Scariant?
Dr Kanan Purkayastha

Omicron, the new coronavirus variant labelled as being ‘of concern’ by the World Health Organization (WHO), was present in the Netherlands before the first cases were identified in South Africa. The Dutch Health Authority RIVM has reported cases dating back to 19 November, although it was not known if those people were infected outside the country.

The World Health Organization began naming the variants after Greek letters to avoid public confusion.  Hence the new variant was named after the 15th letter of the Greek alphabet. There are now seven “variants of interest” or “variants of concern” and each of them have a Greek letter. WHO also skipped two letters just before Omicron — “Nu” and “Xi”. Some suggests that ‘Nu’ can be confused with ‘new’ and ‘Xi’ can be confused with the name of the Chinese president Xi Jinping.

Omicron’s rapid rise in South Africa is what worries researchers most, because it suggests the variant could spark explosive increases in Covid-19 cases elsewhere. On 1 December, South Africa recorded 8,561 cases, up from the 3,402 reported on 26 November and several hundred per day in mid-November, with much of the growth occurring in Gauteng Province, home to Johannesburg. On 18 December 2021, UK recorded approximately 25,000 Omicron cases. Although genome sequencing is needed to confirm Omicron cases, some PCR tests can pick up a hallmark of the variant that distinguishes it from Delta.

Epidemiologists measure the epidemic’s growth rate using R, the average number of new cases spread by each infection. In late November, South Africa’s National Institute for Communicable Disease (NICD) in Johannesburg determined that R was above 2 in Gauteng. Gauteng’s R value was well below 1 in September — when Delta was the predominant variant and cases were falling — suggesting that Omicron has the potential to spread much faster and infect vastly more people than Delta.

When I am writing this piece, I come to know that in London, Omicron accounted for more than 44% of cases and was expected to become dominant very soon. R value in UK is between 3 and 5. Question is - can Omicron overcome immunity from vaccines or previous infection? The research showed that Omicron reduces the levels of coronavirus-fighting antibodies 30-fold, leaving the double vaccinated at far greater risk of catching the virus. A researcher at Oxford University looked at blood samples taken from people who had two doses of either Pfizer or AstraZeneca and measured the level of antibodies. They found a substantial fall in the number of antibodies able to fight off Omicron compared with Delta variant.

However, the researchers said that other parts of the immune system may still be protective and argued that there was no evidence that the new variant increased the risk of severe disease or death or stopped vaccines being effective against more serious illness. Mathew Snape, a Vaccinologist, from the University of Oxford suggests that ‘we still have not pinned down the threshold of protection and what is enough to prevent infection, or severe disease, or hospitalisation and death.’ Researchers also found that other parts of the immune system, particularly T cells, may be less affected by Omicron’s mutations than are antibody responses.

A team of virologist at the NICD and the University of Witwatersrand in Johannesburg has measured the ability of neutralizing, or virus-blocking antibodies triggered by previous infection and vaccination to stop Omicron from infecting cells, in a laboratory test.  Another South Africa-based team at the African Health Research Institute in Durban has conducted a similar test on virus-neutralizing antibodies using infectious SARS-CoV-2 particles. Researchers at the University of Texas, who is collaborating with Pfizer–BioNtech to determine how its vaccine holds up against Omicron, have found that T-cells, a type of white blood cell that determine our bodies’ immune response to antigens, in people who have had the Pfizer vaccines continue to protect against severe illness despite Omicron’s ability to evade other defences. This is the case for other vaccines as well. Researchers from the University of Cape Town also suggests that ‘what we know about T-cells in general and in particular with Covid-19 is that while T-cells don’t prevent infection, they do work to give a level of protection against severe disease, and in that respect the data is reassuring if what we are seeing is right.’ Researchers in UK have also found that the third dose of vaccine can increase the immunity against Omicron by three fold. 

It is the unvaccinated population who are easily infected by Omicron than vaccinated population. South African experience so far suggests that Omicron though highly transmissible, the percentage of death is much lower than other variants. Also victims recover faster and may become less infectious just 3-5 days after a positive test. Research at the University of East Anglia also suggests that people are most infectious first five days, after which time infectiousness falls. US medical policy advisor Dr. Anthony Fauci said the variant was not a cause for panic, but that it was a cause for concern. The US Centres for Disease Control and Prevention has already taken action, expanding its vaccine guidance to recommend that all US adults get a booster shot.

Research suggests that the third dose can supercharge neutralizing-antibody levels and it is likely that this will provide a defence against Omicron’s ability to evade these antibodies. It has also been observed that people who had recovered from Covid-19 months before receiving jabs had antibodies still capable of blocking the mutant spike. This suggests that people with repeated exposure to SARS-COV 2’s spike protein, be it through infection or a booster dose, are ‘quite likely to have neutralizing activity against Omicron.’

So, it has been argued in the political arena that isolating people for ten days when they are no longer infectious will harm the economy and leave vital public services such as National Health Service short staffed. A suggestion in UK is that people could perhaps take a daily lateral flow test and be allowed to leave quarantine if they test negative for two or three days in a row.

Above all, Omicron is a new variant, but it is also a scariant because of our previous experiences about Covid disease from SARS-COV-2. Early reports linked Omicron with mild disease, raising hopes that the variant might be less severe than some of its predecessors. Every research team around the world is now trying to find out some data that can reflect their own immunological landscape. However, very soon we will know firmly that it is not as severe as we thought for well vaccinated population.

 

The writer is a UK based academic, chartered scientist and environmentalist, columnist and author