As airports slowly return to normal operations, as national Covid-19 measures abate and international lists of safe travel countries are drawn up, airports have introduced various Covid-19 test methods to help contain the spread of the virus.
In addition to temperature controls and forced Covid-19 tests, a new method is being tried to identify passengers who have tested positive for the virus. the use of medical sniffer dogs. A dog screening trial was recently held on six dogs trained by the Medical Detection Dogs charity to recognize the smell produced by people with Covid-19.
During the trial, the dogs were able to correctly identify 88% of the Covid-19 cases; However, they also mistakenly flagged 16% of people who tested negative. The research is at an early stage where these false positives could improve over time.
We speak to Prof. James Logan from the London School of Hygiene and Tropical Medicine to learn more about the study and the possible future use of Covid-19 detection dogs in the airport area.
Frankie Youd (FY): What was your commitment to the trail and how did you come up with the idea of using dogs?
James Logan (JL): I directed the study, I was in charge of the whole thing. I started working with Medical Detection Dogs, the charity. We built on our previous work on malaria, in which we showed that malaria has a specific odor and that medical sniffer dogs can be trained to detect the odor of malaria.
When Covid-19 happened, I contacted the same team I had previously worked with and asked, “How about we do that with Covid-19?” That is where it all started.
FY: Could you provide some background on the process and how it was carried out?
JL: A really big part of the process was collecting samples from people. We involved over 3,500 participants and they donated their scent samples. They wore socks, a T-shirt and a face mask, which they then sent to us. They were PCR tested so we knew if they were positive or negative, and then the dogs went through various stages of training.
They started with a small number of samples where we checked to see if Covid-19 had a smell and if the dogs detected anything. It was clear very quickly that there was a smell.
We then moved on to the next phase, which was to train the dogs and make the dogs understand that the smell they were looking for was the positive Covid-19 smell and the negative Covid-19 smell to ignore – people who tested negative by PCR.
Photo credit: Neil Pollock.
It is really important for them to be exposed to both because you want them to learn to ignore anything that is background noise. This could be the smell of a hospital that some of the samples were from, or it could be the smell of someone at home, or maybe they have some other illness so make sure to ignore this and just focus on the Covid-19 – Focus on smell.
FY: Where did the samples come from? Were different variants presented?
JL: We had a mix of people; People with severe symptoms, they were in the hospital but not on a ventilator. We’ve had people who were mild, that is, they didn’t have a cough, but they had a headache, or they had a sore throat or other symptoms. Then we had people with no symptoms whatsoever.
We tested the so-called alpha variant, the original variant from last year, for most of the samples, but towards the end of the study we had samples of the so-called Kent variant. We had two different variants in there and the dogs that were trained on one variant still discovered the other. We didn’t test the Delta variant, the Indian one, but we have no reason to believe that they wouldn’t recognize it too.
FY: What are the benefits of using dogs to detect Covid-19?
JL: One is accuracy; We have good accuracy for people with a low viral load. Lateral flow tests show that the efficiency drops very quickly as the viral load decreases. If you are in the early stages of the infection or are asymptomatic, a lateral flow test will not capture this very well; a PCR test will not take it. But even with very, very small amounts of the virus, the dog is still ingesting the virus, which is incredible.
“The real key to this is speed. Each individual dog could examine up to 300 people per hour. “
But the real key to this is speed. Each individual dog could examine up to 300 people per hour. We were at Heathrow Airport, we spoke to border guards, we saw dogs on duty looking for drugs and explosives, there is already a precedent there, dogs are already being used in this environment just as we would check people for Covid19.
If you imagine people getting off a plane they would walk past two dogs, these two dogs are monitoring a plane full of 300 people in the time it takes these people to get off the plane. No additional queues or tests need to be performed.
Photo credit: Neil Pollock.
In this scenario, some of these people would test positive and those people would be asked to step aside and then either they would be quarantined or they would have a PCR test done. Instead of what we are seeing now, a whole level of people going into quarantine, the bulk of it is unnecessary as the majority of people are not infected. With dogs, you would have a smaller sample of people going through this process, and most people would go and go home.
People pay a lot of money for tests in terms of cost, but to be examined by a dog you would talk about pennies, less than a pound per person.
FY: What are the challenges of using dogs?
JL: The biggest challenge is how it is deployed and how it is scaled. We have to think about how many dogs we need to make a difference at an airport, that’s what we’re working on right now.
Is it doable? Yes, but we have to figure out the challenge of getting enough dogs. We would certainly not see a dog on every flight at every airport, that is not feasible. Next we need to figure out how to use it in the smartest possible way. For example, if we can have a dog at the gate on high risk flights, or if those flights need to be quarantined, the dogs are better used for amber countries where there is a medium risk.
That is what we are discussing with the government and with the airports about how this could work. So this is the biggest challenge, but we think we can overcome it.
FY: Are there any plans for more human testing?
JL: We are currently in talks with the UK government. Lots of discussions with airports and airlines to find out what the next steps will be. The next phase of research is to bring the dogs into the real world.
We now have around 20 dogs being trained for this. Instead of rehearsing in a pot, as was done in phase one, they are trained on t-shirts that real people wear when they walk past the dogs, and they do well.
Photo credit: Neil Pollock.
The next step is to deal with people who are actually infected. We don’t think there is any reason to believe it will be any different so we are very hopeful.
FY: Do you think the use of dogs could aid future airport Covid-19 screenings?
JL: Yes, it doesn’t replace anything, it won’t replace clinical testing, it has to be viewed very much as a screen. Instead of calling it a diagnostic test, let’s call it a public health tool.
“I would love to see this at the entry points because I think dogs could solve a lot of our problems. I think there is a real opportunity there.”
I would love to see this at the entry points because I think dogs could solve a lot of the problems we have. I think there is a real chance there. In the future, I would love to see how dogs play a role in helping this pandemic. It’s not going anywhere, it certainly won’t be gone in six months, a year – we’ll likely live with Covid-19 in various ways now and forever and have vaccination programs.
We also have to think long-term. While there may be logistical challenges in getting a lot of dogs outside, we have quite a long time to eventually get dogs there. And not only for this one, but also for the next, we have to be prepared for that. One way to do this is to have something like dogs that are quick to train and quick to deploy. As part of our preparation for the next one, we might have dogs ready to go.
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