Background: Despite the high infectivity of severe acute respiratory syndrome coronavirus 2, the incidence of coronavirus disease (COVID-19) in some parasite endemic regions such as Africa has been slower than predicted. Parasites are proficient immunomodulators and may affect the incidence and clinical severity of COVID-19. We aimed to investigate a possible association between parasitic infections and COVID-19. Methods: An ecological study in which we compared the COVID-19 cases and deaths with schistosomiasis, soil-transmitted helminths and malaria cases per country and WHO region. To determine the ecological associations, we performed correlation, linear and logistic regression, and geographical information services analyses. Results: As of May 4 th 2020, 216 countries and territories from 6 WHO regions had reported 3.34 million COVID-19 cases and 238,628 deaths. Africa reported 0.029/3.3 million (0.88%) cases and 1,064/238,628 (0.45%) deaths. In 2018, Africa reported 213/229 million (93%) of all malaria cases, 204/229 million (89%) of schistosomiasis cases, and 271/1068 million (25%) of soil-transmitted helminth cases globally. In contrast, Europe reported 1.5/3.3 million (45%) of global COVID-19 cases and 142,667/238,628 (59%) deaths. Europe had 5.8/1068 million (0.55%) soil-transmitted helminths cases and no malaria/schistosomiasis cases in 2018. We found an inverse correlation between the incidence of COVID-19 and malaria (r -0.17, p =0.002) and COVID-19 and soil-transmitted helminths (r -0.25, p <0.001). Malaria-endemic countries were less likely to have COVID-19 (OR 0.51, 95% CI 0.29-0.90; p =0.02). Similarly, countries endemic for soil-transmitted helminths were less likely to have COVID-19 (OR 0.24, 95% CI 0.13-0.44; p<0.001), as were countries endemic for schistosomiasis (OR 0.22, 95% CI 0.11- 0.45; p<0.001). Conclusions: Parasite endemic countries had comparatively lower COVID-19 cases and deaths than non-endemic areas. Further studies to elucidate whether the immunomodulation induced by parasites has a protective effect against COVID-19 in individuals are warranted.
Keywords: Malaria; Schistosomiasis; Soil Transmitted Helminths; Parasites; COVID-19; sub- Saharan Africa