New model to estimate impact of interventions in controlling COVID-19 pandemic: Study

Berlin, May 17: Researchers have developed a computer model to evaluate the effectiveness of interventions aimed at preventing the COVID-19 pandemic's spread, an advance that may help public health experts determine scenarios for upcoming weeks.

The scientists, including those from the University of Gottingen in Germany analysed German COVID-19 case numbers with respect to past containment measures, and derived scenarios for the coming weeks.

Their findings, published in the journal Science, may provide ways to derive insights about how well the measures to contain the pandemic have worked in recent weeks, and how things will continue in the coming weeks.

In the study, the scientists simulated the course of the COVID-19 pandemic in Germany since mid-March. Their model calculations related the gradually increasing restrictions of public life in March to the development of COVID-19 case numbers.

In particular, the study examined the effect of three packages of interventions in Germany in March -- the cancellation of major public events around March 8, the closure of educational institutions and many shops on March 16, and the extensive contact ban on March 22.

The scientists combined data on the temporal course of the COVID-19 new infections with a disease transmission model. This allowed the analysis of the course of the pandemic to date, and the investigation of scenarios for the future, they said.

According to the computer models, the packages of measures initially slowed down the spread of COVID-19, and finally broke the dreaded exponential growth. "Our analysis clearly shows the effect of the various interventions, which together ultimately brought about a strong trend reversal," said Viola Priesemann, study co-author from the Max Planck Institute in Germany.

The scientists said they did not only have Germany in mind for making the predictions. The model calculations show us the overall effect of the change in people's behaviour that goes hand in hand with the interventions, added Michael Wilczek, research group leader and another co-author of the study.

"From the very beginning, we designed our computer model so that it could be transferred to other countries and regions. Our analysis tools are freely available on GitHub and are already being used and developed further by researchers around the world," said Jonas Dehning, lead author of the study.

The scientists said they are currently working on applying the model to other countries. They said it is particularly important to work out the different points in time at which the measures were taken in different countries, from which conclusions can be drawn about the effectiveness of the individual measures.

The study's findings for Germany, on the basis of case numbers up to April 21, indicated an overall positive development of case numbers for the coming weeks. However, they also revealed a critical challenge in assessing the epidemic dynamics. Changes in the spread of the coronavirus are only reflected in the COVID-19 case numbers with considerable delays, the scientists explained.

"We have only recently seen the first effects of the relaxation of restrictions of April 20 in the case numbers. And until we can evaluate the relaxations of May 11, we also have to wait two to three weeks," Wilczek said.

The scientists said they are continuing to monitor the situation very closely to evaluate the new case numbers and assess whether a second wave is to be expected. They also hope to show how the number of new cases might develop further. If the relaxations of May 11 doubles the infection rate, they said, a second wave can be expected in Germany.

Instead, if the infection rate balances the recovery rate, the new infections stay approximately constant, the scientists noted in the study. However, they said the number of cases can continue to decrease if people continues to be very careful, and contact tracing by health authorities is effective, and at the same time new outbreaks of infection are detected and contained early. "How exactly the numbers will develop in the future, therefore, depends decisively on our behaviour, the observance of distance recommendations and hygiene measures," Priesemann said.