Miền Bắc Are 'COVID Toes' a Real Symptom of the Virus

Some unusual symptoms have been linked with COVID-19. One of the most surprising is the so-called "COVID toes"—a red or purplish rash or raised bumps typically on the tips of the toes.

Experts had been unsure whether COVID toes were actually linked to COVID-19 (or just some odd coincidence in some patients), but some research suggests a connection.



A small study, published on October 5, 2021, in the British Journal of Dermatology, analyzed 63 people with redness and swelling in their hands and toes, also known as chilblain-like lesions (after chilblains, a condition triggered by exposure to extreme cold temperatures). Fifty of those study participants had COVID toes, according to the researchers; all had tested positive for the virus. Thirteen of the study subjects were determined to have chilblains lesions unrelated to the coronavirus.

The researchers found that both groups developed their symptoms as a result of an immune response containing high levels of certain autoantibodies, especially an antibody called type I interferon. The endothelial cells, which make up the thin membrane that lines the inside of blood vessels, also seemed to play a role.

The language in the study is pretty medical jargony, but dermatologist Ife J. Rodney, MD, founding director of Eternal Dermatology Aesthetics and a professor at Howard University, broke it down. "As with other viral infections, your body mounts an immune response in an attempt to fight off the COVID-19 virus," Dr. Rodney told Health. "This immune response causes inflammation throughout your body that can present in a variety of different ways on the skin." Interferon is a protein involved in inflammation, added Dr. Rodney.

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That can lead to rashes that may feature flat, red spots, and some may be itchy or even painful, said Dr. Rodney. "In COVID toes, the inflammation also damages small blood vessels in the toes, leading to a reddish-purple discoloration of your skin." That discoloration is usually seen in a condition called chilblains, said Dr. Rodney. "We are unsure why the COVID rash takes on this specific presentation, as it does not seem to be more common in the wintertime or related to cold exposure," added Dr. Rodney.

Why Some People Who Have COVID-19 Get COVID Toes

It's not entirely clear, but "the reason why some people experience these symptoms more than others is likely because of differences in the degree to which one person's immune system reacts versus another person's," Joshua Zeichner, MD, director of Cosmetic & Clinical Research in Dermatology at Mount Sinai Hospital in New York City, told Health.

Keep this in mind, though, per infectious disease expert Amesh A. Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security in Maryland: "COVID toes are not a very common phenomenon, but do occur and should prompt medical evaluation."

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When Did Doctors First Start Seeing COVID Toes?

According to Podiatry Today, in a blog post written by Tracey Vlahovic, DPM, a doctor of podiatric medicine, news of COVID toes first surfaced in April 2020. Dr. Vlahovic stated in her article that a colleague had sent her a PowerPoint presentation from another doctor in Spain, Maria del Mar Ruiz Herrera, in which the Spanish doctor described "skin manifestations of COVID-19 as a chilblains-like lesion or as a vasculitis-like presentation on fingers and toes that can occur in children, teenagers and adults who have been diagnosed as positive for COVID-19 or are asymptomatic."

According to an April 14, 2020 news article in the New York Post, the General Council of Official Colleges of Podiatrists in Spain sent out a press release in April 2020 after podiatrists began "registering numerous cases of sick people, mainly children and young people, who had small dermatological lesions on their feet." Sometimes COVID toes appeared in the absence of other COVID-19 symptoms; sometimes, they developed before the appearance of other symptoms.

These lesions, per the council, were "purple-colored" and typically popped up around the tips of the toes, though they usually healed without leaving marks on the skin. The council compared the marks to those that result from chickenpox, measles, and pernio (another term for chilblains).

COVID toes may have been detected as early as March 2020. The International Federation of Podiatrists published a case study detailing similar findings, describing a 13-year-old boy who suddenly presented with lesions on both feet. Two days later, he presented with general COVID-19 symptoms—fever, muscle pain, and headaches—along with "intense itching and burning on the foot lesions." The boy was never tested for COVID-19, nor were any other family members, but his sister and mother showed symptoms of coronavirus before the boy's symptoms manifested. The boy's foot lesions began to clear up within a week, per the report.

On the other hand, some studies called into question whether such lesions really are a symptom of the virus at all. A research team in Belgium, reporting in the June 25, 2020 issue of JAMA Dermatology, described 31 mostly teenage and young adult patients with purplish-red lesions on their toes and/or fingers. None tested positive for the SARS-CoV-2 virus, which causes COVID-19, and all were negative for antibodies to the virus.

Researchers suspect that these patients' skin symptoms may have been due to community containment and lockdown measures imposed as a result of the pandemic. A majority (64%) reported decreased physical activity and more time spent in sedentary positions as they worked from home or were homeschooled. Notably, most patients indicated that they remained barefoot or in socks most of the day.