Tracers have reached only half of people who have been in contact with coronavirus patients in a town fearing a local lockdown.
Cases are still rising in Blackburn, Lancs, prompting public health officials locally to advise people to take greater precautions.
But Professor Dominic Harrison, public health director in the town, now says only about 50% of people are being successfully tracked down by contact tracers.
Last week he warned that Blackburn could yet face a local lockdown like that in Leicester unless people rigidly adhered to the new guidelines, which included limits on gathering sizes and encouraging people to elbow bump rather than hug.