Prophylactic effect of cutaneous leishmaniasis against COVID-19: A case-control field assessment.

INTRODUCTION: We assessed the possible relationship between the COVID-19 with laboratory-confirmed CL-registered cases with a history of scar compared with healthy volunteer participants. METHODS: This case-control retrospective study was conducted in southeastern Iran with a high anthroponotic cutaneous leishmaniasis (ACL) burden. RESULTS: Overall, n=1,010 cases of CL consisting of n=479 male and n=531 female were analyzed for probable infection with SARS-CoV-2. Altogether, in the case group, two men and one woman (0.3%) were afflicted with a mild form of COVID-19 disease, and none of them were hospitalized or died. In contrast, out of n=2,020 healthy participants, n=57 (2.9%) contracted laboratory-confirmed COVID-19, including mild (66.7%), hospitalized (26.3%) and critical and death (3.5%, each). There was a strong negative association between CL infection and COVID-19. The burden of COVID-19 in CL-cured participants significantly reduced the morbidity (OR=0.12, CI: 0.03 - 0.30 and P <0.001) and mortality (percentile: -4.10, -0.02). CONCLUSION: Participants with a history of previous CL scar significantly prevented the incidence of COVID-19 morbidity and mortality. The cross-protection mediated by the CL-cured cases would presumably retard COVID-19 in endemic countries. However, further longitudinal studies are needed to explore the potential profile and duration of this protection offered by CL against COVID-19.