Corona forecasts: second “just-in-time” lockdown – Coronavirus Vienna

Forecasts on the development of new coronavirus infections are important for the timely implementation of measures to prevent overload of the health system. Since the beginning of April, researchers from the Vienna University of Technology, MedUni Vienna and Gesundheit Österreich GmbH (GÖG) have been making a weekly forecast for the next eight days. Anything beyond this period should be considered scientifically quite doubtful, said Florian Bachner of the GÖG on Thursday in Vienna.

In the latest post on Wednesday, the Covid forecasting consortium of the three research groups, experts “also assumed an average of 6,200 new cases per day for the next several days,” Bachner reported in the background discussion. On Wednesday exactly 6,211 positive tests were recorded across Austria within 24 hours, shortly after the media event, 7,416 new infections were reported on Thursday. However, there are fluctuations related to the days of the week, so the GÖG expert responsible for coordinating the forecasting consortium emphasized the importance of the average value.

The second important part of the forecast is a capacity forecast for hospitals. “Analogously to dynamic case events, a significant increase is to be expected,” explained Bachner. The calculation of the model released Wednesday assumes an increase to 760 patients in intensive care units by November 18. That would be a doubling from the beginning of this week and a 38 percent utilization of all adult intensive care beds, Bachner emphasized. This is a critical value considering that around 60 percent of intensive care beds are needed acutely, that is, after accidents or due to interventions that cannot be moved.

In their calculations, experts assume that 6.8 percent of those newly infected are currently hospitalized with some delay. 5.7% end up in normal wards, 1.1% in intensive care units. According to Bachner, there is an average surface duration of 10.4 days in normal care and 12.6 days in intensive care, and intensive care patients still need about four days of normal care before they can leave the hospital.

It happened for the first time in the week before last that “the forecast has reached an area that is critical to the system,” said complexity researcher Peter Klimek of the Complexity Science Hub (CSH) at MedUni Vienna. Previously, only a slight increase was assumed. The forecast was sent to the Corona Traffic Light Commission and a warning from the model computer was relayed.

It is not yet clear why the new infections “skyrocketed” so unexpectedly, as Klimek put it. “We can’t explain it causally,” he said. The CSH expert suspects “an interaction of the most varied seasonal effects”, such as the shift towards closer contact in closed rooms. There are factors such as that resources for contact tracing are becoming scarce or the climate is cooling, which can only be seen “afterwards,” said Martin Bicher of the Vienna University of Technology. “We don’t know when something like this will happen.”

Furthermore, the calculations are subject to structural uncertainties. “No one should trust him,” emphasized Martin Zuba of the GÖG. For the finished forecast, the different calculation models from the three research institutions are “superimposed and an average is formed,” Bachner explained. That would then be more accurate than individual models and the international “state of the art,” Klimek said. “It is very important that we take and compare different models,” said simulation researcher Niki Popper from the Vienna University of Technology. The researchers involved would also discuss their assumptions, and not just “compare numbers.”

The second block came “on time from my point of view,” Bachner said. In Austria, the goal of doing this was given as the ultimate consequence, Klimek emphasized. He expected the first effects to occur between four and ten days after the entry into force of the measures and that the figures would decline by at least two weeks. First, a peak in new infections is reached, only later one of the active cases and with a greater delay in hospitalizations, said TU expert Bicher. After the tightening of the planned measures for at least a month, only a gradual easing can be expected, he explained.