Study adds to evidence suggesting that SARS-CoV-2 infection doesn’t cause an inflamed-toe condition called chilblains, but it doesn’t close the door.
, is an immunological deep dive, examining 21 people who developed chilblains during the early months of the pandemic in Connecticut. Although the results don’t rule out a direct connection between COVID-19 and chilblains, the authors couldn’t find any immunological evidence of a past SARS-CoV-2 infection in 19 of those people. The report adds to the argument by some researchers that ‘COVID toe’ could have been caused by something unrelated to the virus.
Still, the results raise “some very interesting questions that deserve further study”, says Freeman, who was not involved in the research. For instance, the study doesn’t exclude the possibility that people exposed to the virus could have fought it off using an innate immune response — a first-line defence that would not prompt the body to produce detectable antibodies and T-cells against SARS-CoV-2. So for now, she adds, the mystery remains.How chilblains arise isn’t entirely clear.
The researchers used a variety of methods to look for antibodies and T-cells specific to the coronavirus — signs of the body having what’s called an adaptive immune response to a pathogen. These people were months past the onset of their chilblains, so their immune systems would have had plenty of time to respond to SARS-CoV-2 if they had been infected. But the team picked up signs of a past infection only in two people, one of whom had initially tested positive.
Many groups have tested people with chilblains for SARS-CoV-2 antibodies, but “nobody had looked really into this hypothesis about the T-cell response”, Freeman says. “The team did a fantastic, really extraordinary job.” But she emphasizes that the study is small — and therefore not necessarily generalizable — and that much larger epidemiological studies