Apr 16: Model calculates effect of various corona exit scenarios

As soon as steps are taken to slowly come out of the corona lockdown, it is important to be able to predict the effects of those steps. UMC Utrecht professor of epidemiology Mirjam Kretzschmar and her group have developed a calculation model that can help with this.

For example, if it is soon decided to open the schools again, you want to know what the implications are for the number of additional infections. “We then enter all kinds of data in our model. For example, the infectiousness of children. But also how much social contact they have with other age groups. Based on these figures, the model calculates how many additional infections from such a measure can be expected. Of course, such a prediction stands or falls with the accuracy of the data entered into the model.”

Mirjam Kretzschmar's group specializes in mathematical models and infectious diseases. “We usually work on models about HIV infection or antibiotic resistance. Now we have used all our capacity to find solutions regarding the corona crisis.”

Contact detection

Her models predict, for example, the effect of washing hands, the use of mouth masks and social distancing on the spread of the virus. But also about the effect of contact detection. The latter is very topical because of the development of apps that may be used to alert people if they have been in the vicinity of a corona patient.

“One may wonder, for example, how well contact detection works if there are many people who are infected, but who are not aware and have no or hardly any symptoms. Our model shows that if this proportion is higher than 30 percent, a detection app does not have that much influence on limiting the number of infections. If, on the other hand, social distancing is really complied with at the same time, a detection app can have a limited additional effect. In this sense, it can therefore be an additional tool to manage the epidemic by reversing the current lockdown measures.”

Different scenarios

Various scenarios are conceivable in the exit strategy. Opening the schools is often mentioned. But you could also choose to have certain age groups go back to work. Or make bars and restaurants accessible again for a certain age group. “The effect of all these scenarios can be calculated with our model. Not very precise, because you do not know the exact figures, for example, how often a 30-year-old person has contact with an 80-year-old. But you can approach the effect well enough to allow it to play a role in deciding whether or not to do so.”