Autumn 2020 saw a strong surge in the number of people who tested positive for COVID-19. More stringent measures were introduced, followed by a significant, but relatively short-term downward trend. This decrease coincided with a significant change in behaviour, measured in mid-November. For example, Dutch people indicated that they avoid busy places more often than six weeks earlier (67%, compared to 58% previously). They also found it easier to do so, possibly as a result of the more stringent measures. This was clear from the eighth round of the behavioural study conducted by RIVM, the Netherlands Municipal Public Health Services and Medical Assistance in Accidents and Disasters (GGD-GHOR) and the Municipal Public Health Services (GGDs).