Since the beginning of the Covid-19 pandemic, several models have been developed to predict the spread of the virus, the number of deaths, and the load on the medical care system in Sweden. Researchers have now summarised and evaluated the models of Covid-19 for the Public Health Agency of Sweden. The report shows that the pandemic models helped us to understand the development of the pandemic, but at the same time it illuminates some deficiencies. When a new virus with the potential to spread all over the world is discovered, things need to happen quickly. The period from the discovery of the virus to it having spread across large parts of the world and affecting huge numbers of people in a pandemic can be as short as two months. Several epidemiological models were used in Sweden during 2020 to help planning in healthcare regions and decision-making on the national level.
Models are useful in the planning of measures
The authors of the report conclude that several of the prediction models helped to understand how the pandemic developed. These models were useful in planning the measures to take, and showed that the spread of infection would probably differ significantly between different parts of the country. Further, models of various scenarios showed that changes in patterns of social contact would affect the rate of the spread of infection.
However, the report found consistent deficiencies in many of the models.
“One deficiency was that in several cases it was not clear which data had been used, and what the true intention had been of the information. It’s important for the recipient that this is unambiguous, such that decisions can be taken based on the model to the extent that this is possible”, says Anna Jöud, docent at Lund University.
Important to evaluate the models
“Our evaluation shows that it is necessary to standardise documentation and communication of the models and their predictions. It is also important that the assumptions on which the model rests are clearly stated”, says Philip Gerlee, docent at Chalmers University of Technology.
“The COVID-19 Forecast Hub in the US is a good example. This allows predictions of the pandemic development to be shared as they are made, such that other analysts and researchers can later evaluate how well the prediction agreed with the outcome. This will help us to find out which methods work well. It would be a good idea to set up a similar programme in Europe”, says Toomas Timpka.