Can I take another job during the crisis?

This depends on your current category of status. Tier 2 workers are permitted to take supplementary employment, but this is limited to work either in shortage occupations or in the same profession and at the same level as the current sponsorship. It is not yet clear whether a sponsored worker who is furloughed by their sponsor will be permitted to carry out alternative employment for a different company, so at the current time it would be risky for a Tier 2 worker to attempt this. Tier 4 students often have limited work permission, particularly during term-time. Although colleges and universities are closing, this does not automatically mean that UKVI will accept that we are in a vacation period, allowing full-time work. Unless clear UKVI guidance is given to confirm that students may currently work full-time, it would be safest to stick within any existing work restrictions.