The high demand for coronavirus tests has forced the government to change the way it operates smaller test sites in Cambridgeshire.
Residents had been able to drop in on specific days at mobile testing sites in various locations including Ely, Wisbech, Huntingdon and St Neots.
But a surge in demand in the last week has meant a re-think of the approach was needed and tests are now appointment only or through using home testing kits.
Fenland District Council said in a Facebook post last week: “Please be aware that following an increase in demand all tests at the additional mobile testing site on Chapel Road, Wisbech, must now be booked in advance.
“Please do not turn up for a test without an appointment.”
The National Testing Programme is operated by the Department of Health and Social Care which had been relying on local authorities to help publicise where and when coronavirus tests were available.
As demand is exceptionally high at the moment and the tests are now appointment only, some residents have not always been able to book at the time and location they wish.
Dr Liz Robin, director of public health for Cambridgeshire and Peterborough, said: “We know it may not always be as easy as the government would like it to be for people to access a test close to where they live.
“If you are in that situation, don’t give up, please keep trying.
She added: “If you’ve tried to book a test for coronavirus and you’ve not been able to, or you’ve been offered a location which is too far away, our advice is to wait a few hours and try again.
“If you have symptoms of coronavirus, please don’t give up when trying to book a test - keep trying and continue to self-isolate for the full ten days if you are unable to get a test.”
Testing for Covid-19 is only available by calling 119 or booking online.
No walk-in options available at any coronavirus testing site or at accident and emergency departments.
Booking slots for the tests are available the evening before for morning appointments, and on the morning for afternoon appointments.
People are being urged not to book a test unless they have at least one of the symptoms of coronavirus - a fever, new continuous cough or a loss or change in your sense of taste or smell.
Dr Robin said: “If you don’t have symptoms of coronavirus - a fever, new continuous cough or a loss or change in your sense of taste or smell – and have not specifically been asked to take a test, please don’t book one.
“By doing so, you might be denying someone who genuinely needs it.”
Meanwhile, one Ely school principal criticised the government in his response to national media reports that there are no coronavirus tests available in the country’s top 10 virus hotspots.
Richard Spencer, executive principal of Ely College, said: “If this [report] is true it is appalling.
“The education sector has risen to the challenge of reopening with no financial support, inadequate and late guidance, and an exams fiasco as backdrop.
“It ALL hinges on the government playing their part with a functioning track and trace system.”
The Department of Health and Social Care hasn’t commented specifically on the situation in Cambridgeshire.
A spokesperson said: “NHS Test and Trace is working, our capacity is the highest it has ever been and but we are seeing a significant demand for tests.
“New booking slots and home testing kits are made available daily for people with symptoms and we are targeting testing capacity at the areas that need it most, including those where there is an outbreak, and prioritising at-risk groups.
“Our laboratories are processing more than a million tests a week and we recently announced new facilities and technology to process results even faster.
“If you do not have symptoms and are not eligible to get a test you can continue to protect yourself if you wash your hands, wear a face covering and follow social distancing rules.”