Global concern over a new strain of coronavirus, dubbed BA.2.86, or Priola, is growing after it was named as a variant under monitoring by the world Health Organization.
So far, only a few cases worldwide have been confirmed but exactly what threat could this new variant pose? We asked Prof Paul Hunter, an expert on emerging infectious diseases based at the Norwich Medical School of the University of East Anglia to give us the lowdown.
What is BA.2.86 and why has it been labelled a variant of interest?
It's a daughter of the BA.2 variant, which was as an Omicron variant that appeared in December 2021. It has a lot of mutations compared to BA.2 – 35 or 36. A year ago, we'd have said that anything that's got 36 mutations is probably going to be something to be really concerned about.
But most of the mutations have already been seen in other variants. So, we've already got some degree of background on it.
However, you can’t say that because it has 36 mutations compared to BA.2 that it’s really scary. It may or may not be, and I’ll say this repeatedly, we just haven't seen enough cases to really nail any of this down at the moment.
How many cases of BA.2.86 have been recorded?
On the recording website covSPECTRUM, it says there have been 27 sequences reported so far. Now, covSPRECTRUM is a really good website for following these things, but it does often take about a week or so for things to appear. So, I think it's almost certain that there are more than that now.
Do we know where BA.2.86 came from?
Not a clue. The initial variants were identified in Israel and Denmark but I don't think anybody believes that’s where it first appeared. I've heard some people suggest it might be Africa, possibly Southern Africa, but we just don't know to be honest.
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Could BA.2.86 cause more severe disease than previous variants?
Just 27 infections reported globally isn’t enough to tell us anything about the symptom profile. The big question is whether it's going to be cause more severe disease. And by severe disease, I mean being so sick that you need supplementary oxygen, or you need to be admitted to hospital, not just a really bad head cold that leaves you feeling drained for a few days.
And the problem is that, again, there are just 27 infections reported so far, it's not enough to make a judgement. But what we have seen with each successive wave of new variants since the appearance of Omicron back in December 21 is that, by and large, they've caused less severe disease.
There are good reasons for that. Firstly, most of us in England have already had two infections, at least, of COVID. And secondly, if you've been vaccinated and you've had an infection, you've got what's called hybrid immunity, which gives really good protection against severe disease.
I expect that to continue with this variant. But again, until we've seen more cases, we can't be definitive.
How transmissible is BA.2.86?
There are two issues that affect transmissibility. The first is how intrinsically transmissible a virus is. The second is how easily a virus is able to evade immunity. So, if you've got a very highly transmissible virus, but everybody's immune, it's not going to spread. And similarly, if you have a not very transmissible virus, but if everybody's immune naive, then it will spread.
BA.2.86 does seem to have an advantage in evading immunity and vaccine compared to BA.2, but only of the level that we've seen in other variants recently. It looks like it's not that much more transmissible then EG.5.1 (also known as Eris) that peaked sometime late July or early August and now seems to be on the decline.
Will a normal lateral flow test pick BA.2.86 up?
I believe so, as much as they pick any other variants up. Lateral flows are not 100 per cent reliable. I'm sure you've heard stories of people who thought they had COVID and were testing negative for days and then one came up positive.
But I've not seen any evidence to show that BA.2.86 would be any less likely to be picked up by a lateral flow then other circulating variant. But again, it's too early to know, to be honest.
Will the current vaccines be effective against BA.2.86?
Forgetting about BA 2.86 at the moment, the current vaccines generally only provide immunity against infection for four to six months. And, certainly a couple of months after you've had a booster, your immunity starts to wane.
But we no longer rely solely on vaccine for immunity. For the vast majority of us, our immunity is a mixture of prior infection and vaccine. Prior infection provides better immunity to severe disease than vaccine. But neither provide very durable immunity to reinfection.
This means that when you get reinfected you're a lot less likely to end up in hospital. As it stands at the moment, vaccines will probably be no less effective against this variant than they have been against EG.5.1.
Now that we're heading into autumn and winter, typically a time when COVID cases rise, is there a possibility of more lockdowns?
In medicine and epidemiology, you never say never. But I think it’s extraordinarily unlikely that we would be wanting to implement any further restrictions.
You’re trying to balance the benefits against the hazards. Up until Easter 2021, the benefits of what we call non-pharmaceutical interventions probably outweighed the harms that they did. But since then, the harms have probably outweighed the benefits.
Viruses that cause repeated infections generally level out at what's called the endemic equilibrium, which is the sort of the average infection that you're going to get over the course of the year.
Most of these viruses are seasonal, so most of those infections tend to occur November to February, and then drop out during the summer.
You can show this with modelling that once a virus hasa approached the equilibrium, these sorts of non-pharmaceutical interventions aren't what drives infection rates. What drives infection rates is the rate at which immunity is lost.
Further lockdowns would bring with them considerable harm, as they did in the first year, but probably wouldn't have many benefits now. So I can't see it ever happening with this virus.
About our expert, Prof Paul Hunter.
Paul is professor in medicine at the Norwich Medical School of the University of East Anglia, where he studies emerging infectious diseases.
His research has been published in the journals Risk Analysis, Journal of Long-term Care and Eurosurveillance.
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