Where did the UK go wrong? And how will it prevent further deaths if a secondary pandemic wave occurs as it reopens? Modelling and epidemiology give us some clues.
1. Lockdown was too late
The UK acted too slowly in imposing its lockdown on March 23, which allowed the initial infection to quickly spread out of control. This was the case with infections within the UK and those coming from abroad.
We know that the initial spread of coronavirus is exponential. The initial reproduction, or “R” number in the UK was estimated to be 2.6, meaning that for every person infected, another 2.6 further infections occurred. This quickly increased the size of the epidemic in the initial couple of months while it was crucially important to attain control of the virus.
A recent study suggests that most COVID-19 introductions in the UK occurred during March 2020 and that 34% of UK infections originated in Spain, 29% in France, 16% in Italy and 23% in other countries. If the lockdown had been imposed sooner and travel between countries stopped earlier, it’s possible a number of infections and deaths could have been prevented.
As long as there is some infection in the population, secondary infections will occur and the virus cannot be fully suppressed and controlled.
In the initial stages of the epidemic, the UK did not account for infections and deaths in settings other than hospitals, crucially leaving out those that took place in care homes.
4. Missing symptoms
The UK has been been much slower than other countries in telling people what COVID-19 symptoms to look out for, with a heavy focus on cough and fever.
A loss of taste and smell was added to the UK’s official list of symptoms on May 18, more than a month later than in France and almost a month after a study suggested these as clinical symptoms of infection.
5. Failure to test, trace and isolate
But in a situation where we do not know the extent of asymptomatic COVID-19 infection, it might have been better to encourage testing of symptomatic people and start the tracing of contacts of positive people sooner. This is how South Korea controlled its epidemic. In the UK, testing was not scaled up and manual contact tracing only launched on May 28.
How to get the pandemic under control
Since the onset of the pandemic, I have been using mathematical modelling to understand how to control the transmission of COVID-19 and determine the best strategy to exit the lockdown.
Our recent pre-print study suggests that reopening schools as the first step towards reopening society, even if done gradually, must be accompanied by a large scale and well-functioning testing, tracing and isolation strategy.
To prevent a second wave after reopening schools as the first step in exiting lockdown, the UK will need to trace around 50% of people with symptoms and 40% of their contacts, and isolate all symptomatic and diagnosed cases.
The UK can turn the coronavirus epidemic around with a strong test, trace and isolate strategy. Our modelling results suggest that if this is comprehensive and efficient, the government can prevent a secondary pandemic wave and bring the number of infections and deaths down.