Omicron: How dangerous is it?

It’s now almost 3 weeks since we learned of the emergence in southern Africa of the highly-transmissible Covid variant that the WHO christened “Omicron”. Helen Rees runs a medical research laboratory at the University of the Witwatersrand in Johannesburg. She also chairs South Africa’s medicines regulatory board - the equivalent of our MHRA - and is an advisor to the WHO for the southern African region. She told Chris Smith what they’re seeing so far…

Chris - For the moment, though, people who do succumb with don't know how serious the infection is going to be. But one way we can get some insights and try to find out is to look at the situation in South Africa where they're several weeks ahead of us, and now have had the chance to study the impact of the new variant on their populace.

Sally - Helen Rees runs a medical research laboratory at the University of the Witwatersrand in Johannesburg. She also chairs South Africa's medical regulatory body, the equivalent of our M HRA and is an advisor to the World Health Organisation for the Southern African region. She told Chris what they're seeing so far.

Helen - If we look at a month ago, South Africa's numbers of new COVID cases were really quite low. Between 100 & 200 a day with very few deaths. I think the population was feeling quite comfortable, but with Omicron, the numbers have really gone up extremely rapidly. It appears at the population level that this is a very transmissible variant. That means it spreads pretty easily. And we first saw it in groups of young people, but mostly mild and moderate disease.

Chris - When you say a big increase in numbers, you've gone from a few hundred cases per day. What sorts of numbers are we seeing now?

Helen - We've gone up to about 11,000 in a day, and it's going up. A particular concern was that this started in Parklands South Africa, which is the province with the highest population numbers. So many of the cases that we're seeing are in this province, but we are now seeing the numbers going up in other provinces as well.

Chris - I've visited Johannesburg many, many times. I've been on the roads and I've seen how people get to work. I've seen how people live in the environs of Gauteng. To what extent do you think your experience of the very rapid spread is a consequence of those factors versus actually it's the virus that is very, very transmissible?

Helen - Well, I think it's a combination of both. Undoubtedly, the conditions in which people live very close together very often particularly in the inner cities, in formal settlements and packed high rise and dense housing. That is one issue. But when numbers go down, people will become relaxed and they stop using all the public health and social measures that we keep talking about. Young people relax in particular. When we first saw these cases, it was in groups of young people. But I do think that the third issue here is undoubtedly to do with the virus being more transmissible. We saw this similarly with the Delta variants. So once we get these changes, we have to try and understand whether the changes we're seeing in the virus for a new variant actually do change the way it behaves. And it does seem to be more transmissible.

Chris - One crucial question must be who is catching this? Now you've said it first surfaced in younger people, but are these younger people who are vaccinated? Is it younger people who've previously been infected with coronavirus and recovered, and now they're getting this variant again? Is it unvaccinated individuals? Is it a mixture?

Helen - First of all, in terms of 'who is getting admitted to hospital?' It does seem that we've had a shift from older people to a younger age group, teenagers, but also children under five. Now that could be because our vaccination coverage is much higher in older people so it could be that what we're seeing is the protection of older people. But it's not completely that. The young people being admitted, the duration of stay in hospital is much shorter and in terms of disease severity, it seems to be less severe than we saw with the Delta variant. That's one piece of good news, but of course, with large numbers of people infected in the community we are seeing the numbers of admissions going up. Now your other question is, 'are these vaccinated, unvaccinated or people who've had infections?' There's two things there. One is that we are seeing people who've previously had an infection, a proven infection, that they are becoming reinfected. We're also seeing people who've been fully vaccinated, also becoming infected. However, in both cases, we're not seeing such severe disease. So although we're seeing vaccine breakthrough infections, we seem to be not seeing such severe disease.

Chris - Do you have a feel for what proportion of people are ending up having to come to hospital? Because that's of course the really big question when governments around the world are trying to safeguard their health service provision. They've got an eye on potential case burden and how many of those cases are likely to translate very quickly into cases that need hospitalization. So what fraction under these circumstances are ending needing hospital care, compared with Delta that we already have some familiarity with?

Helen - It's difficult for us to say what fraction because many people, especially with mild or moderate disease and many people will be asymptomatic, they're simply not testing. The people who are tending to test at the moment are people with more severe symptoms. So it's difficult to say how many people have got there, but what we are not seeing is the same steep rise of hospital admissions as we saw with Delta. Although the number of cases that we are detecting is going up very rapidly with Omnicon, we are not seeing the same sort of rise that we saw with Delta, which does suggest that the severity of the disease might be less so than we saw with Delta. We are obviously looking at this very closely, but at the moment, that's the impression that many clinicians have got. What we do know is the majority of people who are being hospitalized are the unvaccinated. So clearly vaccination is giving some degree of protection to those who are vaccinated.

Chris - Is South Africa currently growing the variant in the laboratory and doing the sorts of experiments that we really are aching for the answers to where we take antibodies that people have made in response to the vaccines that we've administered so far and asking the question, 'how many antibodies do I need in order to block the growth of this virus?' So we can work out whether the population is vaccinated or not really at the moment.

Helen - Yes, those studies are already well underway. In fact, we've already seen results of one of the studies. In that study, they looked at the new variant and they looked at how effective people who'd had the Pfizer vaccine were and how effective that vaccine was at neutralizing that virus. There was a really significant reduction in the effectiveness, but it wasn't a wipeout, it didn't get rid of the protective effect of the vaccine antibodies completely, which is encouraging because that means that we would anticipate that these highly effective vaccines would continue to have protection, even if that protection is somewhat reduced.