By David Tuller, DrPH
Can Dogs Smell Compounds Associated with Host Response in Long Covid?
It can be unwise to pay attention to research published on a pre-print server before it has been through a peer-review process. Although passing through peer-review is itself no guarantee of quality, the process represents at least one layer of scrutiny. Nonetheless, some pre-prints just catch the eye. Like this one from France, titled Screening for SARS-CoV-2 persistence in Long COVID patients using sniffer dogs and scents from axillary sweats samples.
So here’s the short version: In this study, dogs trained to suss out the odors of chemicals produced as part of the host response to a SARS-CoV-2 infection identified them in sweat samples from 23 out of 45 patients with long Covid but in none of 188 samples from healthy controls. If the canine olfactory skills are accurate and these results hold up under review, the lack of any false positives in particular is especially remarkable. The findings imply that a sub-group of these long Covid patients–around half–could be experiencing a chronic SARS-CoV-2 infection.
[*I removed a section indicating that the full study had not been post, only the abstract. I was mistaken and have removed that section. I apologize for the error.]
With that caveat, below is the abstract:
“Objectives: Dogs can be trained to identify several substances not detected by humans, corresponding to specific volatile organic compounds (VOCs). The presence of VOCs, triggered by SARS-CoV-2 infection, was tested in sweat from Long COVID patients. Patients and methods: An axillary sweat sample of Long COVID patients and of COVID-19 negative, asymptomatic individuals was taken at home to avoid any hospital contact. Swabs were randomly placed in olfaction detection cones, and the material sniffed by at least 2 trained dogs. Results: Forty-five Long COVID patients, mean age 45 (6-71), 73.3% female, with prolonged symptoms evolving for a mean of 15.2 months (5-22) were tested. Dogs discriminated in a positive way 23/45 (51.1%) Long COVID patients versus 0/188 (0%) control individuals (p<.0001). Conclusion: This study suggests the persistence of a viral infection in some Long COVID patients and the possibility of providing a simple, highly sensitive, non-invasive test to detect viral presence, during acute and extended phases of COVID-19.“
Long Covid and the Labor Shortage
With the pandemic entering its third year and with the omicron wave still to hit its peak, it is likely that 2022 will see even more attention to and analysis of the societal impacts of long Covid. This week, the Brookings Institute, a center-left think tank in Washington, D.C., published an article assessing the possible relationship between long Covid and an employment market with more than 10 million unfilled jobs across the country. The conclusion: About 15% of the current labor shortage could be related to long Covid.
Katie Bach, the author of the article and a senior fellow at Brookings, notes that the calculations rely on multiple assumptions that might or might not be correct. And one reason it is necessary to make so many assumptions is the current shortage of data and metrics involving those reporting prolonged symptoms after an acute infection. We know little about these people, how many there are, why they stay sick, or what the impact is on their lives, she writes. Among these knowledge gaps is the fact that public health and economics experts have almost no understanding of long Covid’s economic burden.
Bach indicates that government agencies are still not collecting much of the information needed to conduct proper analyses of the impact of long Covid. This includes, for example:
“*The number of full-time equivalent workers currently not working due to long Covid (including those at reduced hours)
*Average time off or time spent at reduced hours due to long Covid
*Workplace accommodations that would enable long Covid patients to increase working hours
*Applications, approvals, and rejections for Social Security Disability Insurance among long Covid patients“
The article concludes:
“Access to this data will help policymakers and businesses better predict how today’s labor market conditions may evolve. It may also prompt the government to improve disability standards so that people with long Covid can request accommodations or secure benefits; issue health guidance that takes into account the economic burden of large-scale disability; and provide more federal dollars for long Covid research and medical care. The possibilities are vast, but first, we need the data.“