Abstract: Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active. International Journal of Antimicrobial Agents 57 (2021) 106248 Contents lists available at ScienceDirect International Journal of Antimicrobial Agents journal homepage: www.elsevier.com/locate/ijantimicag A COVID-19 prophylaxis? Lower incidence associated with prophylactic administration of ivermectin Martin D. Hellwig a,∗, Anabela Maia b a b Plymouth State University, 17 High Street, Plymouth, NH, USA Rhode Island College, 600 Mount Pleasant Avenue, Providence, RI, USA a r t i c l e i n f o Article history: Received 20 June 2020 Accepted 22 November 2020 Keywords: SARS-CoV-2 COVID-19 Prophylaxis Ivermectin Mass drug administration Prophylactic chemotherapy a b s t r a c t As COVID-19 (coronavirus disease 2019) continues to rapidly spread throughout the world, the incidence varies greatly among different countries. These differences raise the question whether nations with a lower incidence share any medical commonalities that could be used not only to explain that lower incidence but also to provide guidance for potential treatments elsewhere. Such a treatment would be particularly valuable if it could be used as a prophylactic against SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) transmission, thereby effectively slowing the spread of the disease while we await the wide availability of safe and effective vaccines. Here, we show that countries with routine mass drug administration of prophylactic chemotherapy including ivermectin have a significantly lower incidence of COVID-19. Prophylactic use of ivermectin against parasitic infections is most common in Africa and we hence show that the reported correlation is highly significant both when compared among African nations as well as in a worldwide context. We surmise that this may be connected to ivermectin’s ability to inhibit SARS-CoV-2 replication, which likely leads to lower infection rates. However, other pathways must exist to explain the persistence of such an inhibitory effect after serum levels of ivermectin have declined. It is suggested that ivermectin be evaluated for potential off-label prophylactic use in certain cases to help bridge the time until a safe and effective vaccine becomes available. © 2020 Elsevier Ltd and International Society of Antimicrobial Chemotherapy. All rights reserved.