Will Covid-19 sniffing dogs allow fans back into sporting events?
Nearly 100 million people are expected to watch Super Bowl LV in Tampa, the first time the big game has been held during a pandemic (the World Series has survived two). But only 22,000 of those viewers, 7,500 of them vaccinated healthcare workers, will be in actual attendance, representing just one-third the capacity of Raymond James Stadium. Social distancing and face-coverings will be enforced. The first few rows will be kept clear as a buffer between the field and the fans. By this stage of the pandemic, everyone should be aware that, at any one time, a portion of the population is composed of asymptomatic carriers who can infect others they come into contact with. As a result, any large gathering has the potential to become a super-spreader event with wide-reaching consequences. Large-scale testing at gatherings such as sporting events is limited by the availability of trained personnel, equipment, money, and the time it takes for the results of the actual test to work.
But an unconventional solution may be in the works.
Recently, the Miami Heat announced they are trying a new tactic to screen fans beyond the now familiar temperature checks and questionnaires. The NBA franchise will employ Covid-19 sniffing dogs. While the idea may seem far-fetched, there is some basis in science and actual application. Dogs have been employed to sniff out drugs and explosives and even some medical conditions such as cancer. Additionally, K-9 units have been employed for years to detect explosives at the Super Bowl. Fans have been routinely screened on and off-site before walking into stadiums on game day.
A dog’s nose has about 300 million scent receptors, which is 50-60 times as many as the average human. It is thought that the breakdown process in the body that occurs with infections or cancers leads to the release of odor molecules called volatile organic compounds (VOCs). These VOCs then enter the air where the scent can be picked up by a properly trained dog.
There are currently two studies published looking at whether dogs can detect Covid-19. The first study came out of Germany in July 2020. It was published in the journal BMC Infect
Diseases and was noted to be simply a pilot study. In it, eight dogs were trained to detect Covid-19 in respiratory secretions from hospitalized patients versus non-infected patients. The canines were able to detect 94% of the positive samples. This certainly sounded promising, but some critics argued that the dogs may have simply learned the scent of the positive patients since there were only seven subjects. Others pointed out that the samples were from hospitalized patients and therefore may have had more virus than asymptomatic carriers.
A second study aimed to answer whether dogs could pick up Covid-19 from sweat alone, rather than respiratory secretions. It was published in
December 2020 in the journal PloS ONE. In this study, researchers from France and Lebanon collected swabs from underneath the arms of patients with and without Covid-19. The success rate per dog ranged from 76% to 100%. This is notable, as the detection rate of current Covid-19 nasal swab tests also falls in this range (80%-100% depending on timing of symptoms). It also appears that a detection dog may be able to sense Covid-19 in samples that have much less virus material than the more expensive genetic tests being used in hospitals across the world.
Several international airports have also begun to utilize Covid-19 sniffing dogs. In Chile, passengers pass through an airport health checkpoint where they wipe their necks and wrists with gauze pads that are sent to dogs for analysis. In Helsinki, arriving international passengers first collect their luggage and then are asked to collect samples of sweat by wiping their necks. But, with the Super Bowl only a week away, it is unlikely we can get a new squad of dogs trained in time. According to the lowest estimate, a dog can be trained in just a week or two to detect the coronavirus,. But other research suggests it takes up to eight weeks for a dog that is already trained in detecting non-Covid scents, or up to six months for a dog that has never been trained for detection.
One question that does come to mind is, if a dog is smelling so many Covid-19 positive samples, can the dog itself become infected? Scientists believe it is rare for a dog to become infected with the virus and they aren’t sure if it can pass the disease onto humans. Overall, it seems that Covid-19 sniffing dogs may be part of an answer when it comes to screening large groups of people passing through a designated area, like a sports arena. More rigorous studies are needed, but we may start to see more sporting events utilizing these canines as supplements to existing protocols. Covid-19 sniffing mascots may very well be coming to a sports team near you. The next time you attend a big sporting event, shortly after you get your ticket scanned and pass through a metal detector, you may also be swabbing your armpit for a dog to sniff.
Jonathan Gelber MD is a surgeon and specialist in sports medicine.