COVID toes: where do we stand with the current evidence?
Autor
Baeck, Marie
Herman, Anne
Institución
Resumen
Background: Numerous of cases of chilblains have been observed, mainly in young subjects
with no or mild symptoms compatible with COVID-19. The pathophysiology of these lesions
is still widely debated and an association with SARS-CoV-2 infection remains unconfirmed.
Objectives: This paper focus on the unresolved issues about these COVID toes and in particular
whether or not they are associated with COVID-19.
Arguments:
- The temporal link between the outbreak of chilblains and the COVID-19 pandemic is a first
suggests a link between the two events.
Journal Pre-proof
3
- Positive anti-SARS-CoV/SARS-CoV-2 immunostaining on skin biopsy of chilblains seem
to confirm the presence of the virus in the lesions, but lack specificity and must be
interpreted with caution.
- Conversely, RT-PCR and anti-SARS-CoV-2 serology were negative in the majority of
patients with chilblains. Therefore, SARS-CoV-2 infection can be excluded, with relative
certainty, even after accounting for possible lower immunization in mild/asymptomatic
patients and for some differences in sensitivity/specificity between the tests used.
- Some authors hypothesize that chilblains could be the cutaneous expression of a strong type
I interferon (IFN-I) response. High production of IFN-I is suggested to be associated with
early viral control and may suppress antibody response. However, the absence of other
cutaneous or extracutaneous symptoms as observed in other interferonopathies raises
unanswered questions.
- To date, a direct link between chilblains and COVID-19 still seems impossible to confirm.
A more indirect association due to lifestyle changes induced by lockdown is a possible
explanation. Improvement of chilblains when protective measures were adopted and after
lifting of lockdown, support this hypothesis.
Conclusion: Conflicting current evidence highlights the need for systematic and repeated
testing of larger numbers of patients and the need for valid follow-up data that take into
consideration epidemic curves and evolution of lockdown measures.