Public Health

Debate between Craig Mackinlay and Philippa Whitford

Tuesday 30th November 2021 Commons Chamber

[Dr Whitford]

I was not claiming that it was, because genomic testing takes a couple of weeks generally and it is therefore too late for someone to isolate. What I am saying is that with this variant, as in alpha but not in delta, the missing S gene means that on that initial test—which takes six hours or until the next day, or whatever it is—we already get a heads-up that we are dealing with an omicron case. We can go on to do the genomic analysis, but we can say to the patient, “We think you have this variant. You need to isolate thoroughly and for longer.”

[Craig Mackinlay]

I thank the hon. Lady for bringing her medical knowledge to the House. It is very interesting, particularly on the S gene. I do not know what magic goes on in a lateral flow test. We put the drips in at one end and then one band, hopefully, appears and not two. Could a lateral flow test be adapted to be specific for this type of variant?

[Dr Whitford]

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.