Brexit hasn't really happened yet and this virus hasn't properly arrived in the UK yet. Its arrived in Italy though and already over 460 people have died in the last few days. Its NOT flu, its about ten times more deadly than flu. Hence the travel restrictions in Italy.
Anyone who runs a real business (i.e. not a kerbside/backyard trader) should take the threat seriously and plan for a lean few months. Hopefully it won't hit as hard as some expect, but in business its best to plan for the worst and hope for the best.