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. 2021 Jan:102:53-55.
doi: 10.1016/j.ijid.2020.10.021. Epub 2020 Oct 16.

COVID toes: where do we stand with the current evidence?

Marie Baeck  1 , Anne Herman  2
Affiliations

COVID toes: where do we stand with the current evidence?

Marie Baeck et al. Int J Infect Dis. 2021 Jan.

Abstract

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. 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.

Keywords: COVID toes; COVID-19; RT-PCR; SARS-CoV-2; acral lesions; chilblains; pandemic; serology tests.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

None
Graphical abstract
Fig. 1
Fig. 1
Clinical aspect of the COVID toes in an otherwise healthy teenager, with purplish-erythematous macules located on the toes.
See this image and copyright information in PMC

References

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