The impact of the COVID-19 pandemic on international researcher mobility

International researcher mobility is a central feature of contemporary scientific systems. However, the impact of the pandemic on the global circulation of scientific talent remains unclear. Using large-scale bibliometric data from Scopus, this study provides a global assessment of how the pandemic disrupted international researcher mobility from 2020 to 2022. We introduce the concept of "lost mobility", defined as the difference between actual movements and those extrapolated from pre-2020 trends. It was estimated at the global level and separately for incoming and outgoing flows in over 100 countries. Globally, mobility fell short of expected levels by about 15,000 movements, or 3.7%. The effects varied widely and asymmetrically across countries. The Nordic countries were affected as well. Iceland experienced significant losses in incoming mobility, while Sweden experienced losses in both incoming and outgoing mobility. Losses in incoming mobility were associated with the institutional context of receiving countries. More democratic countries lost more, and the effect of policy stringency was concentrated in less democratic systems, whereas outgoing mobility showed no comparable institutional or policy signal. The one factor common to both directions was structural: countries dependent on a narrow set of partner countries experienced larger losses. The pandemic did not simply reduce mobility uniformly but reshaped it through the institutional conditions of receiving countries. Inflows and outflows responded to different forces. This asymmetry affects how research systems absorb global shocks. Policies aimed at sustaining scientific mobility during crises cannot treat arrivals and departures as symmetric. Reducing dependence on a narrow set of partners is one structural source of resilience.