Only 5% of voters now see immigration as an important issue, the lowest figure since 1999. The figure was continuously between 30 and 40% for two years prior to the EU referendum, but has been falling nearly continuously since

Of course, attention to basically every other issue has slumped this month. But it is still worth noting that in the past year or so, immigration has quietly dropped off the agenda entirely after playing a prominent and disruptive role in politics for nearly twenty years.

One other interesting side note - the current figure for Coronavirus (85% rating it as important) has only ever been matched by one other issue - unemployment in the early-mid 1980s

https://www.ipsos.com/sites/default/files/ct/news/documents/2020-04/issues_index_april20_cati_v2_public.pdf