I think we would be talking about redesigning the test for a whole new antigen. I mentioned just one advantage that we get from PCR testing, which basically looks at genes�I will not talk about the whole long name and what PCR stands for�and the benefit is that we get a heads-up. I do not think it is feasible on any reasonable timescale to change lateral flow tests, so we are lucky that this one has S-gene dropout and that we will get an early warning.
One issue with focusing only on a day-two PCR and then, if someone is negative, they are released�unlike what is being discussed for domestic isolation�is that the incubation period of covid, generally, is much longer than two days. It has generally been reported as an average of five days and it can extend for longer. If someone who may have had contact arrives in the UK, gets a negative PCR result on day two and then goes about their business, there is a real danger that that is a false reassurance. That is why the Scottish and Welsh Governments have asked for a Cobra meeting to debate the evidence on a four-nation basis and to discuss having at least an eight-day isolation period for travellers, with a negative day-eight test required before people can be released.
The Prime Minister should listen on that, because one issue that we had in Scotland when we tried to maintain stricter and broader hotel quarantine was that the majority of long-haul passengers arrive through hubs such as Heathrow. The devolved nations have no ability to have an impact on that and we should be working with the Republic of Ireland to make the whole common travel area safer from the point of view of how we move about inside it.