Substantial lockdowns around the world have taken their toll on millions of lives and dented economies globally. So it was a relief to hear that the bluntest tool of all in the outbreak management toolbox did actually work. Lockdowns in Europe saved more than 3 million lives, including an estimated 470,000 in the UK, 690,000 in France, and 630,000 in Italy, according to researchers at Imperial College London.
Outbreak modellers found that lockdowns slashed the average number of people that contagious individuals infected by 81%. In the UK, that amounted to lowering the all-important reproduction number of the virus, R, from 3.8 to 0.63, the researchers reported in Nature. In 11 countries from France and Germany to Spain and Italy, lockdowns pushed the R value below one, meaning the epidemics went into decline.
The modelling showed that by 4 May between 12 million and 15 million people in those countries had been infected by coronavirus but “attack rates” varied dramatically, from 0.46% of Norwegians infected to 8% of Belgians. In the UK an estimated 5.1% of people were infected. Prof Axel Gandy, a statistician on the team, said the model suggested “we are very far away from herd immunity”, where at least two-thirds of the population need to have acquired protective immunity to the disease. “We need to tread very carefully,” he added. Click for full article
I read this earlier in the week, and was surprised that the Imperial college narrative has not been challenged, as it goes back to their discredited modelling at the beginning of the pandemic that if nothing was done, over 500,000 lives would be lost. As I posted yesterday, this perpetuates the theory that covid-19 is a lethal disease that only a small percentage (5% -7%) of the population have been exposed to.
The alternative view by a large number of scientists and epidemiologists that covid-19 is a mild disease that a large percentage (up to 74%) of the population has been exposed to, and is on the wane, a view supported by the Oxford Professor Sunetra Gupta. Her group at Oxford produced a rival model to Ferguson’s back in March which speculated that as much as 50% of the population may already have been infected and the true Infection Fatality Rate may be as low as 0.1%. Based on my recent projections, this range is now between 60% -74%. (see recent blog post).
The key difference between the two theories is in the high lethality theory, lockdown “flattens the curve” and suppresses the spread of coronavirus, leading to future waves of infection, whereas with the mild disease theory, lockdown has little effect, and high levels of either acquired or natural immunity lead to the equivalent of herd immunity.
We also have the example of Sweden – the “canary in the mine”, that has an approximately 25% lower death rate than UK while NOT pursuing a lockdwn policy, so the “lockdown saved lives” does not apply – there would be approx 7,000 lives saved in Sweden based on the Imperial college model.
This debate got me thinking about the two million or so vulnerable people with serious co-morbidities in the UK who are “shielding” ie completely locked down until recently. Under both theories, this group of people will always be vulnerable to coronavirus, and may have to self isolate for a long time until a vaccine is developed for that group of people, or to pursue a policy of eradicating coronavirus, which is unlikely to be successful.