Frostbite are benign skin lesions. These swellings are observed more frequently during the Covid-19 epidemic. According to researchers, they result from an effective innate immunity against Sars-Cov-2.  

Frostbite is manifested by red or purplish fingers, sometimes with the appearance of small blisters that can take a necrotic appearance (dead skin). They are painful and generally caused by the cold and dysfunctions in the cutaneous micro-vascularization. However, since the start of the Covid-19 epidemic, the Italians, then the French, have had to consult their doctor more frequently because of the appearance of frostbite. To confirm or not the link between Covid-19 and frostbite, researchers studied 40 people with a median age of 22 years, suffering from this type of lesions and who had been received by the Covid cell of the CHU de Nice. None of these patients had severe disease. All of these people were either case-contact, or suspected of being contaminated, in the three weeks preceding the consultation for frostbite. However, a positive serology was only found in a third of them. As the head of the study, Prof. Thierry Passeron explains, “ It has already been described that generalized skin manifestations, such as urticaria, etc. may appear after a respiratory viral infection, but the occurrence of localized reactions of this type is unprecedented. “. And add ” If the causality between skin lesions and SARS-CoV-2 is not demonstrated by this study, it is nevertheless strongly suspected “. Indeed, the number of patients who presented with frostbite last April is “ particularly surprising “. The causal elements have already been described by other scientific studies, confirming to date the link between frostbite and Covid-19.

To corroborate the hypothesis of an efficient innate immunity (the body’s first line of defense to fight pathogens), the researchers stimulated and measured in vitro the production of IFNa (cells of the immune system that initiate immune responses ) from three groups of patients: those who presented with frostbite, those who were hospitalized and those who developed non-severe forms of Covid. It turns out that the ” IFNa expression level Of the group who presented with frostbite were higher than in the other two. In addition, the rates observed in the groups of hospitalized people are ” particularly low ». The frostbite would therefore be the result of a ” overreaction of innate immunity In some patients who have been infected with the novel coronavirus. The dermatologist nevertheless wishes to ” reassure those who suffer from it: even if [frostbite] are painful, these attacks are not serious and regress without sequelae over a few days to a few weeks. They sign an infectious episode with SARS-CoV-2 which has already ended in the majority of cases. Affected patients cleared the virus quickly and efficiently after infection '.