The new COVID variant: what is Omicron?

The World Health Organisation have given it the name “Omicron” and labelled it as a “variant of concern”. It’s a new Covid-19 variant spotted first by scientists in Southern Africa and now it’s spreading internationally…

Sharon - We only need to go back about 12 days ago, when cases in South Africa numbered 273 for the day. But what happened after that was a rapid rise in cases. 3 days ago there were more than 1,200 cases and yesterday there were more than 3000 cases. It's the rate of rise that really alarmed the ministry of health in South Africa. When they looked to see where these cases were rising, it was in one particular part of South Africa called Gauteng Province. What the ministry of health and scientists did was to target genome sequencing of positive samples from people living in the area and that is how they identified a new variant not seen before, which has a numerical name B.1.1.529, but which the World Health Organisation have gone on to call Omicron.

Chris - Obviously the genetic code can speak volumes about the likely behaviour of a particular viral variant. When you look at the genetic code of this new variant are there any illuminating features?

Sharon - Something that is very striking is that this is the most mutated variant that we've seen today. It's got around 50 mutations in the entire genome, but about 30 of those are really focused on this spike protein. That's the part of the virus that interacts with human cells as it's kind of gaining entry into the cell. We know that that spike protein has got a large number of mutations, more so than previous variants of concern, and several of the mutations we've been able to identify have been seen in other variants of concern that have been linked to increased transmissibility and immune evasion. But there are actually a lot of mutations in this new variant where we don't know whether they'll alter the biology of the virus or not.

Chris - Why would genetic changes in that spike region make us worried? What could they do to the spike which would make that the virus is either worse, more transmissible or does things with vaccines?

Sharon - A change in the genetic code or a 'typo' can actually lead to a change in the amino acid, which is the building blocks of life, and then change the way the virus structure is. That change in structure can change the way it interacts with our cells. It could mean that the interaction with the receptor that it needs to bind onto in the human is different. It could mean that the virus is better able to replicate in cells. So there are a range of ways that the virus can become fitter and it's those mutations that really change the building blocks of the virus and the way it interacts with us that can make a difference.

Chris - Is there any evidence yet from talking to the doctors looking after these 3000 plus cases in Gauteng in South Africa as to the behaviour of the virus? Is it any worse? Is it the same? Is it different to what we're seeing with the Delta virus, which is the dominant variant we've got around the world at the moment?

Sharon - Certainly clinicians that are treating these particular patients have said that they think that they have different sets of symptoms and that their symptoms are less severe. But I think we have to be quite cautious about whether that information is relevant to the UK. The demographic of that region is that the population is younger overall. They have a lower rate of vaccination of the population. The total population with two jabs of the vaccine is 24% and I think that we have to be cautious about whether this is going to cause less severe disease, the same severity of disease, or even at the other end of the spectrum, more severe. We need to do studies very urgently to identify whether these kinds of anecdotal observations are actually the case in the UK.

Chris - And finally, what experiments do we now need to do then in order to learn what threat this does or doesn't pose to us?

Sharon - There's two types of things that we need to do. The first is experiments in the lab, so we need to look whether the virus is neutralized by antibodies i.e. if we have antibodies to the virus, are they less effective at coating the virus and really making the virus less able to interact with ourselves. Neutralisation we need to do, and other types of live experiments to see how this virus interacts with ourselves. The really important studies are also real-world studies. We need to see whether, for example, this does cause a different type of severity of disease by actually observing a severity of disease. We need to look at whether people who've had natural infection before or vaccination are going to be infected with this particular variant or not. These are the critical real-world studies to look up where the vaccination, efficacy and disease severity are affected in any way.