The University and College Union (UCU), a trade union representing 110,000 staff at UK universities, ran a major series of connected strikes in 2018–22. The action has been characterised as "something of a milestone" for "impending service sector strikes of the 21st century." The second round of strikes ran from 25 November to 4 December 2019, and on fourteen days between 20 February and 13 March 2020. Action in 2020 was curtailed by the onset of the Covid-19 pandemic, the economic effects of which in turn worsened the short-term outlook of the USS pension fund.