More than 100,000 passengers have passed through hotel quarantine in England in the five months since the system was set up.
According to National Health Service data, 114,325 travellers stayed in a UK government-approved hotel between February 15 and July 7, after arriving in the country from a red list destination.
The system, introduced while England was in its third national lockdown, is designed to prevent variants of coronavirus being imported to the UK.
The scheme is mired in controversy over the quality of the accommodation provided, cost of the stay and countries included in the scheme.
Red list travellers are required to spend at least 10 days in a designated hotel at a fee of £1,750 ($2,394) per adult.
In the first full week of the scheme, there were just 996 passengers in quarantine.
However, between July 1 and July 7, the most recent period for which data is available, that rose to 10,438 passengers.
Among the countries on the red list are the UAE, South Africa, Brazil and Indonesia. The list originally covered 30 countries but that number has since risen to 60.
The NHS data does not specifically break down the country of origin for travellers entering hotel quarantine but it does show how many red list passengers were tested in its facilities.
According to The National's analysis of the data, based on full-week figures, India made up the largest proportion of red list passengers tested, with 26,464 swabbed since the country was added to the red list on April 23. Of those, 861 tested positive.
Pakistani travellers made up the second-highest proportion of travellers tested (17,984 with 262 positive) followed by passengers from South Africa (8,530 with 78 positive).
The UAE was fourth, with 6,563 passengers tested for Covid-19 and 77 positive.
Overall, of 86,278 red list passengers tested for the virus, a total of 2,868 were positive – 3.3 per cent.
John Strickland, an aviation consultant at JLS Consulting, said hotel quarantine was clearly deterring people from travelling to the UK.
"It puts you off from travelling – it's a loss of time and certainly a big financial cost," he said.
"Airlines would argue there is little to no value in the system."
Red list passengers forced to stay in the hotels have also vented their frustration with the system.
Garikayi Madzudzo, who arrived in the UK from Zimbabwe and completed his quarantine at the President Hotel on Guilford Street in London this month, said he had feared catching Covid during his stay.
"l was worried that if l was to ever catch Covid it would be by Heathrow, simply because of the lack of organisation and the sheer number of security personal loitering around," he said.
"From my observation, this quarantine process is not working as smoothly as it should."
He said the food supplied by the hotel was not good enough.
"The food portions are small," he said.
Britain's main opposition Labour party supports hotel quarantine as "one of the tools to manage our borders".
But Yvette Cooper, Labour MP and chairwoman of the home affairs select committee, said it was troubling that the hotel quarantine system was unable to more swiftly expand in response to overseas outbreaks.
She criticised Home Secretary Priti Patel for allowing imported cases of the Delta variant, first detected in India, which is now the dominant strain in the UK. India was placed on the red list on April 23, after the country experienced a devastating surge in case numbers.
“I don’t think there’s anybody in the country who thinks that your border policy worked to prevent the Delta variant spreading right across the country and we can see the evidence," Ms Cooper told MPs on Wednesday.
But Ms Patel said the UK had an "end-to-end comprehensive approach" on measures to prevent imported cases.
“That is through the 100 per cent compliance of checks we have in place and of course as the country will be very well aware, with the red, amber, green traffic light system that is put in place," she said.
Transport Secretary Grant Shapps expressed frustration at the number of red list passengers arriving in the UK.
"I also want to point out that people should not be travelling to red list countries. The only people who should be coming back to government quarantine are British or Irish citizens, or people with permanent rights of residence," he told the House of Commons on Wednesday.
"And there should be a limit to the number of people who are still abroad and wishing to return. I sometimes come across cases where people are still using the red list as if it is a case of 'It’s OK, I can come back and hotel quarantine'. That should not be the case."