Effect of co-infection with parasites on severity of COVID-19

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection results in a spectrum of clinical presentations. The effect of co-infection with parasites on the clinical features of COVID-19 is unknown. Methods: We prospectively enrolled consecutive COVID-19 patients and screened them for intestinal parasitic infections. Patients were followed during hospitalization for clinical outcomes. Patients with parasitic co-infection were compared to those without parasitic co-infection. The primary outcome was the proportion of COVID-19 patients who developed severe disease. Factors associated with the development of severe disease were determined by logistic regression. Results: A total of 515 patients with PCR-confirmed SARS-CoV-2 infection were screened for intestinal parasites, of whom 267 (51.8%) were co-infected with one or more parasites. Parasitic co-infection correlated inversely with COVID-19 severity. Severe COVID-19 was significantly higher in patients without parasites [47/248 (19.0%, CI: 14.52-24.35)] than in those with parasites [21/267 (7.9%, CI: 5.17-11.79)]; p<0.0001. There was a significantly higher proportion of patients who developed severe COVID-19 in the non-protozoa group [56/369 (15.2%, CI: 11.85-19.23)] as compared to the protozoa group [12/146 (8.2%, CI: 4.70-14.00)]; p=0.036. Significant higher proportion of the patients presented at baseline with severe COVID-19 in the helminth negative group [57/341 (16.7%, CI: 13.10-21.08)] than in the group with pre-existing helminth infection [11/174 (6.3%, CI: 3.51-11.11)]; p=0.001. In addition, after adjustment for age and presence of comorbidities, COVID-19 patients with any parasite co-infection [aOR 0.41 (95% CI: 0.22-0.77); p=0.006], or with protozoa co-infection [aOR 0.45 (95% CI: 0.21-0.98); p=0.044] as well as those with helminth co-infection [aOR 0.37 (95% CI: 0.17-0.80); p=0.011] had lower probability of developing severe COVID-19 compared with those without parasite, protozoa or helminth co-infection. Conclusion: Our results suggest that co-infection with parasitic co-infection appears to be associated with reduced COVID-19 severity. The results suggest that parasite-driven immunomodulatory responses may mute hyperinflammation associated with severe COVID-19.