The latest watchlist of five coronavirus 'hotspots' in Britain has been released as cases continue to rise.
The ZOE Covid Study has identified the areas where high "prevalence rates" can be found.
Experts have named Liverpool, Dundee City, South Ayrshire, North Lanarkshire and Manchester as the regions to watch.
Read more: North East postcode where 'one in 50 people' have Covid
But the study also found that Britain's 'R rate' is currently at 1.1. - the lowest value seen since the 'third wave' started, The Mirror reports.
A total of 16,703 infections were recorded nationwide on Thursday, figures show, with another 21 deaths.
According to ZOE, on average one in 264 people in Britain are currently estimated to have symptomatic Covid.
The study, based on roughly a million weekly reporters, also found that the number of cases in the 20-29 age group continues to rise.
But cases in the age groups over 30 have begun to level off, it said.
Tim Spector OBE, lead scientist on ZOE and Professor of Genetic Epidemiology at King’s College London, said: "ZOE COVID Study data this week shows rates in former hotspots, such as Scotland and the North West of England, continuing to plateau.
"At the same time, top UK holiday destinations like Cornwall are emerging as new areas with rapidly increasing cases.
"I think this is down to a number of factors, including the sudden influx of holidaymakers over half term, as well as the recent G7 summit and a previously unexposed local population.
"We need to remain vigilant of these UK holiday destinations as summer holidays approach, and ensure that we minimise outbreaks by following government guidelines.
"Since early on in the pandemic, the data from the ZOE COVID Study has shown that there are over 20 different symptoms of COVID-19, not just the classic three: fever, cough and anosmia.
"The COVID-19 situation in the UK is different to last summer due to new variants and the vaccine roll out.
"We’ve found that the symptoms in younger people and post-vaccination are both different.
"People urgently need to know there are more than just the three classic symptoms.
"The top symptoms being currently logged in the Zoe app are; headache, runny nose, sneezing, fatigue and sore throat, which for many will feel more like a common cold.
"The earlier people can catch the infection, the quicker they can self-isolate until symptoms abate and stop the spread.
"We encourage anyone feeling under the weather to take a test as soon as they can and stay at home."
The latest figures come as people in England wait to find out which - if any - countries will be added to the travel green list.
Malta and the Balearic Islands have been slated as possible destinations - although ministers have remained tight-lipped.
