A “circuit break”, in the form of a two-week lockdown during the half-term or Christmas school holidays, could cut Covid deaths by January by between 29% and 49%, depending on the rate of infections in the country, say experts. In a paper that has become central to the debate over what sort of restrictions should be imposed on the UK to turn around the soaring numbers of cases, people in hospital and deaths, scientists modelled what would happen if governments ordered a fortnight’s lockdown. They did not look at the economic consequences. The unpublished data was shared with Sage, the government’s scientific advisory committee on the epidemic. Minutes of the Sage meeting on 21 September show the experts backed the circuit break option – but the prime minister this week announced a new three-tier system of restrictions, which tighten in the areas with the highest rates of infections and hospital admissions. The authors of the paper, which is in pre-print form and has not yet been peer-reviewed, include Prof Graham Medley from the London School of Hygiene and Tropical Medicine, and Prof Matt Keeling and Dr Mike Tildesley from the University of Warwick. They say a circuit break is not a long-term control measure, but would buy time to get the test-and-trace system in better shape. They model several scenarios. In the worst of those, with infection rates rising steeply and little in the way of restrictions, a circuit break could prevent 107,000 deaths by January. But in a statement, the scientists said that very high level of death would not occur, because restrictions would be imposed. “Although there are numbers in the pre-print it is not correct to say that we are forecasting specific numbers of lives that would be saved; the worst-case scenarios would never be allowed to continue without intervention,” they said. Their paper “examines the impact of a short two-week period of intense control. In the paper we time this to coincide with the October half-term to minimise any disruption to education,” they said. “Using two different modelling approaches we show that a short, sharp two-week break leads to a decline in cases, with similar declines in hospitalisation and mortality over a short period – this could potentially reduce the acute load on the NHS enabling it to continue non-Covid care into the winter months.” Using a simple modelling analysis, they said, and looking at the impact of a circuit break during the October half-term on deaths in the medium term, between 1 October and 1 January, the brief lockdown “reduces deaths by approximately 29%” when infection rates are low. “In contrast, when the growth is high, the reduction is approximately 49%,” they say. In the paper, they say that, unsurprisingly, the toughest measures taken bring about the biggest immediate rate of decline in infections and as a result the greatest public health benefits. But there would have to be public buy-in. “The success of any action is highly contingent on the adherence of the populous to the recommendations and rules; a break is only effective if there is an average increase in level of social distancing across the country. “We also consistently find that the optimal time for a break is always now; there are no good epidemiological reasons to delay the break as this will simply push back any benefits until later, leaving more time for additional cases to accumulate,” they write.