So, let’s talk about lock-down as some people don’t seem to get it. First and foremost, lock-down represents a failure of policy and practice. The classic way to control a pandemic is: test, trace, isolate combined with “go in hard, go in early” and some form of social distancing. If you do that, you can be successful, with Korea being the current front-runner for this tried-and-tested approach.
But in the UK, we didn’t do this. To show how laissez-faire we were about SARS-CoV-2, on the day Italy imposed a lock-down in the most affected areas, passengers returning on planes from those areas were not tested and were allowed to travel home on public transport.
What the UK allowed to happen was for the virus to spread largely unchecked for several weeks. To understand why that matters, you need to know a little bit about SARS-CoV-2. First, it’s R-number (a measure of how many people, on average, one infected person will go on to infect) is very high. Early estimates suggested 2.5, figures now seem to suggest R as high as 3.
Scientists were shocked by this finding, because that number is really high for a virus. Seasonal ‘flu is around 1.3 – to 1.4. What it means is that, unchecked, the virus will spread like wildfire through a population.
The reason for this high R number are really interesting epidemiologically. The biggest contributor is that the average period a person is contagious before showing symptoms is 5 days. Again, scientists were shocked by this. SARS and MERS patients (also coronaviruses) only really become infectious when symptoms are obvious. So, you can wander around for 5 days infecting other people completely unaware that you are doing so.
What else do we know? The second thing is how lethal the virus is, it’s infection fatality rate (IFR). Current estimates from serology tests in NY suggest this is around 0.6% – 0.8%. Now, that’s *not* incredibly high. It’s much worse than seasonal ‘flu (H1N1 from 2009 comes in at 0.02%), but nothing like SARS or MERS, where the IFR is 20%.
Still, if left unchecked, the lowest estimate would still kill 390,000 people in the UK.
But here’s the real kicker. Reports coming out of Italy suggested that at least 10% of people who develop Covid-19 need hospital treatment, overall. Again, this is an estimate and possibly a low one – we’ll know more later.
So, let’s “do the math”. Modelling suggests that a virus with R=3 will infect roughly 80% of the population before herd immunity is achieved (as a general rule, the higher R, the higher percentage need to acquire the disease to achieve herd immunity).
The UK has a population of around 65 million. 80% of that is 54 million, 10% of that is 5.4 million. That last figure is the number of hospitalisations the virus could cause. 5.4 million.
I need hardly stress that that figure would destroy any health system in the world in a matter of weeks, resulting in many more excess deaths from both untreated Covid-19 patients and untreated patients with other health conditions.
That’s what the government saw coming down the tubes. Having failed to control the virus in the early stages in the classical manner, they had only one option: lock-down. The virus was simply too widespread and too contagious for anything else to work and prevent the NHS being overwhelmed. The same happened in Italy, France and Spain. It is currently happening in the US.
The government could have put all this information together weeks earlier, as it was already out there. But they didn’t, so we are where we are.