They were at it again last week – warning of a possible huge rise in Covid hospitalisations surging from about 1,000 admissions a day to 7,000 within weeks.
But how confident can we be about forecasts from Professor Neil Ferguson and his colleagues on the Scientific Advisory Group for Emergencies (Sage)?
Although the dictionary definition of sage is 'profoundly wise', from the first appearance of the virus, this government advisory body has been accused of over-egging its predictions in order to frighten Ministers into taking drastic action.
Notoriously, it was Prof Ferguson's apocalyptic report in March 2020 that seemingly dictated policy.
Notoriously, it was Prof Ferguson's apocalyptic report in March 2020 that seemingly dictated policy
The paper by his team at Imperial College, London, warned that in a 'do nothing' scenario – if the Government let the virus take its course without 'non- pharmaceutical interventions' (lockdowns) – there could be 510,000 Covid deaths in two years.
This prompted Boris Johnson's strategy of trying to 'suppress' the virus rather than letting it pass slowly through the population.
But the 510,000 figure was based on the assumption that the overall death rate from the virus, called the infection fatality ratio, was 0.9 per cent – and just a fortnight after the paper was published, one of its authors lowered the estimate to 0.66 per cent.
The actual total number of deaths is currently 135,147.
In October last year, a leaked Sage committee paper warned that under a 'reasonable worst-case scenario' there were likely to be at least 500 deaths a day for 'at least' three months from December to February – amounting to 45,000 deaths.
This turned out to be a big miscalculation the other way. Over those months, there were 63,692 deaths – averaging just over 700 a day.
What Sage had not foreseen was how the Kent variant would be more transmissible than previous strains, leading to more deaths.
In any case, the group's experts had said all along they were just presenting a wide span of 'scenarios' based on assumptions such as the virus's transmissibility, the effectiveness of lockdowns and the success of vaccines.
But the experts took another hit in October with a Cambridge University and Public Health England projection that warned the second wave could peak at more than 4,000 deaths a day over winter.
Cited as being from a Sage sub-committee, it got huge prominence at a No 10 briefing in which the forecast and other models by Imperial College, Warwick University and the London School of Hygiene and Tropical Medicine, which all advise Sage, were presented in a graph showing scenarios of winter-wave deaths.
Imperial predicted deaths could peak at 2,700 a day, and the other two at just under 2,000.
In reality, second wave deaths peaked in mid-January at just under 1,300. As the second wave began to wane, and the vaccination campaign to protect over-50s was in full swing, Sage resolved to warn against society getting back to normal too quickly.
On January 17, Sage member and epidemiologist Professor John Edmunds said it would be 'disastrous' for the NHS if restrictions started to be eased at the end of February. His Sage colleague Dr Marc Baguelin went further, arguing for no easing before May.
Such warnings appear to have been heeded by Ministers, who in late February announced no full end to lockdown until June 21.
Britain's 135,000 Covid deaths are much fewer than the 510,000 feared by Prof Ferguson and his doomsters. Before the next pandemic hits, they would be wise to remodel their modelling systems.