Italy started easing its coronavirus lockdown restrictions from 5 May.
The previous day, 4 May, the Imperial College London released a study which made predictions on the effects in Italy of the new measures introduced. (All references are at the end.)
The predictions considered two hypothetical main scenarios, differing in the increase in mobility of people produced by the less stringent, so-called Phase 2 of the lockdown compared to the period of the most severe lockdown.
The first scenario contemplated an increase in population movements of 20%, and foresaw a potential impact of between 3,000 and 5,000 more deaths, venturing 3,700 as its estimate.
In the second scenario, with an increase in population movements of 40%, the study predicted that Italy would risk between 10,000 and 23,000 more deaths due to coronavirus, with a probabilistic estimate of 18,000.
The research was carried out by the team led by Professor Neil Ferguson, a scholar of mathematical models applied to biology who with his calculations convinced the British government of Boris Johnson in mid-March to change its policy towards social distancing in the battle against the pandemic, and assumes the mobility factor as a point of reference for a more general change in “collective behaviour”.
The use of models for prediction, particularly in epidemiology, is all the rage these days. Another researcher, Professor Giulia Giordano who teaches at the University of Trento, in Italy, has applied mathematical models in a study she co-authored which appeared in Nature, “Modelling the COVID-19 epidemic and implementation of population-wide interventions in Italy”.
In a media interview on 14 May she said that in Italy the epidemic entered the regression phase a couple of weeks ago:
However, what we see today is the effect of the relatively restrictive social distancing and quarantine measures adopted until 4 May. There is a significant delay between the moment of infection, the possible appearance of symptoms and unfortunately a possible death, therefore today’s numbers tell us about the situation of infection in the past. To know where we are now, or to be able to quantify the actual infections that are taking place, we will have to wait at least a week, when today’s infections begin to manifest.
When asked to forecast the effects of the new lockdown phase she answered:
In the absence of other countermeasures, it is inevitable that a loosening of the restriction measures – when there are still so many cases spread throughout the territory, unfortunately not all identified and isolated – will lead to a re-explosion of the infections. The contagion contracts in the presence of measures of social distancing, which reduce the famous reproduction number R0, and explodes as soon as the interactions resume, when the share of infected people comes into contact with a majority of susceptible ones, who can become infected and get sick. [Emphasis added]
Apparently, the models didn’t go very near the truth in the predictions made by either of these two researchers, as, one month into the less restrictive lockdown phase, Italy is moving towards zero new contagions.
It’s possible that this is partly due to the mutation of the virus into a more benign variant, but the fact remains that easing the lockdown doesn’t appear to have had the forecast consequences.
Professor Neil Ferguson, epidemiologist and professor of mathematical biology, leader of the team of the Imperial College London’s study described above, as we said was the one who warned Boris Johnson about the search for “herd immunity” by letting people freer in their movements.
If nothing was done, according to his team’s projections, in the UK 81% of people would be infected and 510,000 would die from coronavirus by August. This model led to Johnson’s U-turn and the lockdown.
And yet Ferguson, who recently resigned from his post as government advisor because found in violation of the lockdown rules he had helped to introduce, doesn’t have a totally unblemished scientific history.
Some in the scientific community consider him an alarmist.
In 2001 Ferguson and his team at Imperial College produced prediction modelling on the UK’s foot and mouth disease outbreak in farm animals, which suggested that animals in neighbouring farms should be culled, even if there was no evidence of infection.
He warned the government that 150,000 people could die. This led to over 6 million cattle, sheep and pigs being slaughtered as a precaution. In the end, a total of 200 people died.
The cost in agricultural revenue to the UK economy of such massacre was estimated at £10 billion.
Experts like Michael Thrusfield, professor of veterinary epidemiology at Edinburgh University, later said that Ferguson’s modelling on foot and mouth was “severely flawed” and that it made a “serious error” by “ignoring the species composition of farms” and the fact that the disease spread faster between different species. “Ferguson was responsible for the excessive killing of animals during the foot-and-mouth disease epidemic of 2001”.
In 2002 Ferguson predicted that between 50 and 50,000 people would likely die as a result of exposure to BSE (mad cow disease) in beef. He also predicted the number could rise to 150,000 if there had been an outbreak among sheep as well. There have only been 177 deaths from BSE in the UK.
Again, in 2005, Ferguson spread panic when he predicted a possible death toll of up to 200 million people from bird flu, telling The Guardian:
“Around 40 million people died in 1918 Spanish flu outbreak,” said Prof Ferguson. “There are six times more people on the planet now so you could scale it up to around 200 million people probably.”
The real number was extremely smaller than that, in the hundreds worldwide over a period of many years.
In 2009, Ferguson and his Imperial College team predicted that swine flu would have a case fatality ratio (CFR, proportion of deaths in those infected) in the range of 0.3% to 1.5%, but believed it was most likely to be 0.4% (4 in one thousand). A government estimate, based on Ferguson’s advice, claimed a “reasonable worst-case scenario” was that 65,000 people in the UK would die from swine flu. The final figure was less than 500, and death rate in those infected with swine flu was of just 0.026 per cent.
Speaking of swine flu in May 2009 on BBC Radio 4’s Today programme, Ferguson said:
“It is likely to spread around the world in the next six to nine months, and when it does so, it will affect about one-third of the world’s population.
An article by The Spectator’s Steerpike reports that Ferguson’s modelling of Covid-19 has been criticised by experts such as John Ioannidis, professor in disease prevention at Stanford University, who said: “The Imperial College study has been done by a highly competent team of modellers. However, some of the major assumptions and estimates that are built in the calculations seem to be substantially inflated”.
On 22 March Ferguson wrote on his Twitter account that the Imperial College London’s model of Covid-19 is based on 13-year-old computer code, that was intended to be used for influenza pandemic, rather than a disease caused by the new coronavirus. Could this be a reason for concern about an outdated model based on a different illness?
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Foto di Jacques GAIMARD da Pixabay