The culture secretary was asked about the boss of Heathrow Airport saying the UK “needs a passenger testing regime and fast” and claiming travellers are being forced to play “quarantine roulette” on Wednesday.
Mr Dowden told BBC Breakfast the “challenge” was ”it is not the case you can simply test somebody and be sure they don’t have” coronavirus.
“It can incubate over a period of time,” he said, “so there’s not a silver bullet of just testing immediately at the border.”
Testing people for coronavirus at UK airports is not a “silver bullet” to ease restrictions for travellers, a government minister has said.
Oliver Dowden made the comments days after the government announced new rules meaning holidaymakers coming from Spain must quarantine for 14 days on their return to the UK.
The UK reimposed the self-isolation requirement for people arriving from Spain on Sunday, making the announcement just five hours before the change in policy came into force.
Heathrow’s chief executive, John Holland-Kaye, called on the government to help ease quarantine restrictions on passengers arriving from higher-risk countries with a scheme for coronavirus tests on landing.
The airport boss said the testing could be “up and running” in a fortnight after Boris Johnson, the British prime minister, warned further European nations could lose their exempted status amid signs of a “second wave” of Covid-19.
Mr Holland-Kaye suggested on Tuesday tests could be done on arrival at a cost of £150, and then a follow-up test done days later.
Speaking to BBC Radio 4’s Today programme, Mr Dowden said: “We are not at the point where there is a viable alternative to the 14-day quarantine.”
“There is a real risk here – the virus is spreading around the world, it’s rising rapidly around the world,” the culture minister added.
“We need to ensure that the measures we’ve taken in the UK – which have been very difficult – to keep this virus under control, do not go to waste because we allow cases to come in from elsewhere.”
The quarantine restrictions for travellers coming from Spain comes amid a spike in cases on the mainland.