London – A coronavirus (COVID-19) variant first identified in India and spreading in parts of the United Kingdom, has threatened to derail Britain’s plans for a return to normality. In allowing the latest lockdown easing, the government stands accused of recklessness. So why has it taken the risk?
Last Thursday 39 of the country’s leading scientists and health experts gathered – via video conference – to discuss the escalating situation.
At the Sage meeting they were presented with a paper by the government’s modelling committee, that made alarming reading.
There was, the document said, a “realistic possibility” that the Indian variant was 50 per cent more transmissible than the United Kingdom (UK) variant which had been responsible for the deadly winter wave.
If this was the case, the modellers said, there was the potential for a summer wave that would be even worse. It could not have been more alarming.
One of those present, Sir Jeremy Farrar, said they faced the “hardest policy decision” of the pandemic – but in the end moving ahead with the roadmap was a reasonable call considering the context.
Dig beneath the headlines and a more complex picture emerges than the 50 per cent figure which grabbed headlines. The term “realistic possibility” is actually a defined phrase, one of several on a sliding scale used by these committees.
It means there is basically a 50:50 chance the modellers are right about the variant being as much as 50 per cent more infectious.
Along with the modelling presented on Thursday, several other pieces of evidence were looked at. Public Health England (PHE) had been gathering data on what had been happening on the ground as part of the test-and-trace programme. It cast doubt on the 50 per cent figure.
A number of things did not add up to its analysts.
Some of the data on “secondary attack rates” – the chances of an infected individual passing the virus on to someone – suggested the variant may be much less infectious than feared.
And it did not seem to be behaving in the same way in every region. A significant cluster has been found in London, but that had not risen at the same speed as it had in Bolton.
The degree of extra transmissibility makes a big difference. A variant that is 20 per cent more transmissible has a much smaller impact on hospital cases.
The sheer volume of imported cases from travellers returning from India – it was argued – could have caused a spike, and explain a big chunk of what appeared to be the extra infectiousness.
One of the problems in nailing how infectious a variant is, is the lag between getting a positive diagnosis from a patient and establishing which variant of the virus caused it. It takes about a week.
So the picture we are looking at is, in fact, out of date.
Another sign being analysed is the latest raw infection rates in hotspot areas – before samples are sequenced. There are now some tentative signs the rapid rises may have started slowing, offering support to the hope the 50% extra transmissibility figure is too high.
What is more, some at the meeting believe the models were too pessimistic – suggesting the vaccination programme will stem the rise in infections or at least limit the scale of serious illness more than the modellers predicted.
“There is a huge degree of uncertainty with this – we have spotted this early and we are still trying to work out what exactly is going on with this variant,” said one of those working on analysing it. (BBC)
