  During the COVID-19 pandemic, governments faced the challenge of managing
population behavior to prevent their healthcare systems from collapsing. Sweden
adopted a strategy centered on voluntary sanitary recommendations while Belgium
resorted to mandatory measures. Their consequences on pandemic progression and
associated economic impacts remain insufficiently understood. This study
leverages the divergent policies of Belgium and Sweden during the COVID-19
pandemic to relax the unrealistic -- but persistently used -- assumption that
social contacts are not influenced by an epidemic's dynamics. We develop an
epidemiological-economic co-simulation model where pandemic-induced behavioral
changes are a superposition of voluntary actions driven by fear, prosocial
behavior or social pressure, and compulsory compliance with government
directives. Our findings emphasize the importance of early responses, which
reduce the stringency of measures necessary to safeguard healthcare systems and
minimize ensuing economic damage. Voluntary behavioral changes lead to a
pattern of recurring epidemics, which should be regarded as the natural
long-term course of pandemics. Governments should carefully consider prolonging
lockdown longer than necessary because this leads to higher economic damage and
a potentially higher second surge when measures are released. Our model can aid
policymakers in the selection of an appropriate long-term strategy that
minimizes economic damage.
