Was the “COVID toes” actually caused by the coronavirus?

Esther Freeman found something strange just as the number of COVID-19 cases began to surge in Boston, Massachusetts in March 2020. Freeman, director of Global Health Dermatology at Massachusetts General Hospital, has seen this type of toe before. Itchy red and purple spots are a typical sign of chilblains and are a skin condition that usually appears in cold weather. But usually she sees one or two cases each winter. “Suddenly I was watching 15 or 20 patients a day,” she says. Interestingly, the surge seen in doctors around the world seemed to be in line with the increase in the COVID-19 pandemic.

Still, when doctors examined people with what the media began to call “COVID toes,” most did not test positive for coronavirus SARS-CoV-2 infection. Scientists were confused and have been searching for answers ever since.

The latest study published on February 25¹Is an immunological detail examining 21 people who developed chilblains during the early months of a pandemic in Connecticut. Although the results do not rule out a direct relationship between COVID-19 and chilblains, the authors could not find any immunological evidence of past SARS-CoV-2 infections in 19 of those people. This report adds to the discussion by some researchers that the “COVID toes” may have been caused by something unrelated to the virus. For example, Jeff Galehausen, a dermatologist and immunologist at the Yale School of Medicine in New Haven, Connecticut, and lead author of the study, was blocked “at home, not wearing shoes or socks.” It may have come from people.

Still, the results raise “some very interesting questions that deserve further research,” says Freeman, who was not involved in the study. For example, this study does not rule out the possibility that people exposed to the virus used the innate immune response to fight the virus. This is a primary defense that does not urge the body to produce detectable antibodies and T cells against SARS. CoV-2. So for now, she added, the mystery remains.

Toe talk

It is not entirely clear how chilblains occur. Patrick McCleski, a dermatologist and researcher at Kaiser Permanente in Oakland, California, said: “We always see some chilblains in winter, but less chilblains in summer.” Researchers say that the cold probably leads to restricted blood flow, killing some cells and initiating an inflammatory process. I’m thinking of letting you. Purple or red spots on the toes (possibly fingers, ears, nose) can be itchy, soft, and in some cases quite painful.

Most people in the latest study developed “COVID toes” between April and May 2020, with a surge in COVID-19 cases in Connecticut. About one-third reported symptoms of COVID-19 before symptoms appeared, and one-third said they had contact with someone who was confirmed or suspected of being infected with SARS-CoV-2. I reported.

Researchers have used a variety of methods to search for antibodies and T cells that are specific to the coronavirus. This is a sign of the body called the adaptive immune response to the pathogen. These people were months after the onset of chilblains, so if they were infected, their immune system would have had enough time to respond to SARS-CoV-2. However, the team found only two signs of past infections, one of which was initially positive.

Many groups have tested people with chilblains for SARS-CoV-2 antibodies, but “no one has actually tested this hypothesis for T cell response,” says Freeman. “The team did a great, really great job.” But she emphasized that this study is small and therefore not always generalizable, and that it is a much larger epidemiological study. doing.^2,3 It shows the relationship between Chilblains and SARS-CoV-2.

Thierry Passeron, a dermatologist at the University of Cote d’Azur in Nice, France, still believes that the toes of COVID are caused by the virus.His team found^Four People who developed chilblains during a pandemic showed evidence of a strong innate immune response. “Few people develop antibodies,” he says, as many people with pandemic chilblains remove the virus this way.

Unsolved mystery

Previous research^Five,6 Chilblains were tested for SARS-CoV-2 infection by performing a tissue biopsy and staining the sample with a dye that identifies part of the virus. Gehlhausen et al. Tried staining and found that it was attached to some of the tissue samples. However, they also tested staining with random tissue samples collected prior to the pandemic when the virus was not circulating and found that it marked some of them. “Our study suggests that the stain may lack specificity,” says Gehlhausen.

The relationship between COVID-19 and chilblains is still questioned, and some researchers have pointed out the blockade theory. This meant that people spent more time at home barefoot in the early stages of the pandemic, literally getting cold. Or, with all media coverage of COVID’s toes, more people than usual may be seeking treatment for the problem.

In Freeman’s case, “The case isn’t closed yet.” On the other hand, she’s seen a patient who, of course, developed chilblains after walking in flip-flops during a snowstorm. Meanwhile, she tested positive for SARS-CoV-2, after which she has seen people who develop chilblains without any other explicit explanation.

The debate is strangely polarized, says Galehausen. However, the hypotheses are not mutually exclusive. “All of this can be true,” he says. “I don’t belong to any team.”

The problem may have diminished. “We’re still looking at new chilblain patients, but it seems a bit back to the old background rate,” says the author of the paper, William Damski, a dermatologist at Yale University.

After all, this question is an interesting scientific debate, but McCleskey says the answer is unlikely to change the way dermatologists treat patients. Chilblains usually disappear spontaneously in a few weeks, regardless of whether a person is infected with COVID-19.

“Honestly, I think I might be able to relax about chilblains,” he says.