Northamptonshire's health experts are concerned by increases in Covid-19 cases in nearby areas linked to Indian variants.
Health Secretary Matt Hancock admitted yesterday Bedford was the "next biggest cause of concern" after Bolton and Blackburn with Darwen.
Surge testing is already under way amid reports that 300 from a local school are isolating, while the government has not ruled out a return to local lockdowns.
Bedford has the second-highest rate of Covid-19 in England, with cases doubling every five days and health officials are warning people to travel to other areas with caution.
Testers are also set to be be deployed in neighbouring Warwickshire after cases of the Indian B.1.617.2 variant were confirmed in Nuneaton.
Northamptonshire's surge in cases post-Christmas was partly blamed on shoppers heading into the county from areas where non-essential retail was in lockdown.
Health director Lucy Wightman said: "We were victim before of being in a geographic location before where all around us had higher rates and inevitably we ended up with that affecting us, pushing our peak further along the road.
"People will remember other areas going into lockdown before Christmas while we didn't until between Christmas and New Year so our peak lasted longer into the New Year.
"Bedford is second on the Chief Medical Officer's watch list so we are keeping an eye on that and keeping an eye on our geography.
"We are asking people to be very cautious about travelling to areas where there are the variants of concern because we don't want to be taking one step forward then two steps back."
Six cases of Indian variants were reported in Northamptonshire last week although the outbreak at a school in Towcester is now thought to have been largely contained.
But Mrs Wightman admitted "only time will tell" if the government allowing relaxation of restrictions to go ahead as planned on Monday (May 17) was the right thing to do.
She added: "I do have concerns over relaxation of restrictions going ahead as planned on Monday
"Touch wood we have a relatively small number of VOCs compared to other areas. But it does appear to be more transmissable and people who are unvaccinated are seemingly experiencing some severe symptoms.
"There is still an enhanced risk with this VOC and I think it would have been useful to understand more about the variant before we undertook the next step.
"But we do have to balance the economic, emotional and physical health risk of continued restrictions against the potential risk of VOCs.
"Sadly it's one of things that only time will tell."
■ Anyone with Covid-19 symptoms — a new continuous cough, loss of or change in sense of taste or a high temperature should self-isolate immediately and book a test online HERE, via the Test and Trace app or by calling 119.