While most people are familiar with the hallmark symptoms of COVID-19 by now—cough, fever, muscle aches, headaches and difficulty breathing—a new crop of medical conditions are emerging from the more than 4 million confirmed cases of the disease around the world.
These include skin rashes, diarrhea, kidney abnormalities and potentially life-threatening blood clots. It’s not unusual for viruses to directly infect and affect different tissues and organs in the body, but it is a bit unusual for a primarily respiratory virus like SARS-CoV-2, which is responsible for COVID-19, to have such a wide-ranging reach in the body. “We see a number of other viruses affect so many different organs in the body,” says Dr. Kristin Englund, an infectious disease expert at the Cleveland Clinic. “But do we see influenza, or other respiratory viruses spread to so many different organs? Not usually.”
The reports of these non-respiratory effects started to build as doctors began treating more and more patients, and much of current scientific understanding of them is still in the early stages, and not confirmed with rigorous studies. But recognizing they exist could help health care professions spot them sooner, and possibly minimize their effects on patients’ health. Here’s a rundown of what the science says, so far, about these lesser-known effects of the disease.
Skin rashes and “COVID toes”
It’s not unusual to see skin rashes in someone with a viral infection, says Dr. Kanade Shinkai, professor of dermatology at University of California, San Francisco, and editor in chief of JAMA Dermatology—think chicken pox, or herpes. There can be two reasons for this: either the invading virus is directly targeting the skin, as is the case with chicken pox in which the virus sequesters in the telltale pustules on the skin, or the lesions are a byproduct of an aggressive immune system fighting mightily against an intruding microbe, like the rash that can form during Epstein Barr Virus or West Nile infections.
“What’s unclear about COVID-19 is whether the rashes associated with infection are specific to the virus, meaning there is actual virus in the skin, or if they are a manifestation of the immune system reacting to the virus that is elsewhere in the body,” Shinkai says.
So far, doctors have reported a range of skin-related conditions that might be connected to COVID-19, including head-to-toe red rashes, hive-like eruptions, blister-like bubbles and even lacy, purply rashes spreading across larger patches of skin. Recently, the lesions that have captured the most attention are red, tender bumps that appear around the toes and heels—dubbed “COVID toes.”
Shinkai says there aren’t enough data yet to determine whether any of these skin symptoms are related at all to COVID-19. Recently, more and more reports of skin rashes are coming to doctors’ attention (often through telehealth consultations), but given the limited amount of testing available in the U.S. to date, not all of these reports have been followed up with COVID-19 testing.
In an effort to address that, dermatologists around the world are starting to create registries of information on confirmed COVID-19 patients and their skin conditions. To begin to see if there is a link between the two, Shinkai says, doctors need to perform head-to-toe exams of every positive COVID-19 patient—“literally looking in between the toes”—to confirm any relevant skin findings. The next priority is looking at the medical histories of patients with rashes, including medications they might be taking that could contribute to their skin reactions. Finally, wherever possible, if the patients agree, doctors should be taking biopsies of skin lesions to test for the presence of SARS-CoV-2.
All of that could be useful in managing patients in coming months and even years, since the skin lesions might be an early sign of infection that doctors could use to guide decisions to advise people to isolate themselves and potentially lower their risk of spreading infection to others. The rashes may also help identify people who might be at higher risk of COVID-19 complications—the lacy purple rashes, for example, are also common among people who tend to develop blood clots, which can obstruct blood flow to the brain and other important organs. “These studies are needed to really help us understand if anything about the skin findings helps us predict who will become ill, and who might experience severe illness,” says Shinkai. “These are critical questions that might allow us to triage people better when they are coming in with infection or even consider different ways to support them through their infection.”