People in Blackburn have been banned from visiting each other in groups of more than two, and told they must not shake hands following a spike in new coronavirus infections.
Health bosses warn that unless the number of new cases goes down, Blackburn with Darwen may have to follow Leicester back into lockdown.
The measures - which also include advice to wear face coverings in all enclosed public spaces - will be in place for the next month.
The authority's director of public health, Dominic Harrison, said a lockdown similar to that in Leicester is "a real possibility" after the infection rate rose to 47 cases per 100,000 from 31.6 in just seven days.