We model fluid-fluid displacement in d = 2 by a diffusion-limited-aggregation (DLA) algorithm which takes random capillary forces into account. Interpore surface tension is neglected. The invading fluid is nonviscous. We find a crossover length L c . On length scales much smaller (larger) than L f , invasion percolation (DLA) patterns are obtained. We argue by scaling, and check by simulations, that L c -(Ap/Ca) s ; Ap stands for a measure of spatial variations of the capillary pressure, Ca is the capillary number, and D s is the interface fractal dimension on small length scales (we find D s ~ 1.3).

A prospective observational study was conducted for assessing the therapeutic efficacy of interferon (IFN)-a2b in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the first month after the coronavirus disease 2019 (COVID-19) outbreak began in Cuba. From March 11th to April 14th, 814 patients were confirmed SARS-CoV-2 positive in Cuba. Seven hundred sixty-one (93.4%) were treated with a combination of oral antivirals (lopinavir/ritonavir and chloroquine) with intramuscular administration of IFN-a2b (Heberon Ò Alpha R, Center for Genetic Engineering and Biotechnology, Havana, Cuba), 3 times per week, for 2 weeks. Fifty-three patients received the approved COVID protocol without IFN treatment. The proportion of patients discharged from hospital (without clinical and radiological symptoms and nondetectable virus by real-time polymerase chain reaction) was higher in the IFN-treated compared with the non-IFN treated group (95.4% vs. 26.1%, P < 0.01). The case fatality rate (CFR) for all patients was 2.95%, and for those patients who received IFN-a2b the CFR was reduced to 0.92. Intensive care was required for 82 patients (10.1%), 42 (5.5%) had been treated with IFN. This report provides preliminary evidence for the therapeutic effectiveness of IFN-a2b for COVID-19 and suggests that the use of Heberon Alpha R may contribute to complete recovery of patients.

Background Effective therapies are needed to control the SARS-Cov-2 infection pandemic and reduce mortality associated with COVID-19. Several clinical studies have provided evidence for the antiviral effects of type I interferons (IFNs) in patients with respiratory coronaviruses. This study assessed the therapeutic efficacy of IFN-alpha 2b in patients infected with SARS-CoV-2 during the first month after the outbreak began in Cuba. Method This multicenter prospective observational study was conducted in 16 hospitals in 8 Cuban provinces. Participants were patients with confirmed SARS-CoV-2 infection detected from throat swab specimens by real time RT-PCR who gave informed consent and had no contraindications for IFN treatment. Patients received therapy as per the Cuban COVID protocol, that included a combination of oral antivirals (lopinavir/ritonavir and chloroquine) with intramuscular administration of IFN-alpha 2b (Heberon Alpha R, Center for Genetic Engineering and Biotechnology, Havana), 3 times per week, for 2 weeks. The primary endpoint was the proportion of patients discharged from hospital (without clinical and radiological symptoms and non-detectable virus by RT-PCR). The secondary endpoint was the case fatality rate (CFR), defined as the number of confirmed deaths divided by the number of confirmed cases. Results From March 11th to April 14th, 814 patients were confirmed SARS-CoV-2 positive in Cuba, 761 (93.4%) were treated with Heberon Alpha R and 53 received the approved protocol without IFN treatment. The proportion of fully recovered patients was higher in the IFN-treated compared with non-IFN treated group (95.4% vs 26.1%, p<0.01). The CFR for all patients was 2.95%, and for those patients who received IFN-alpha 2b the CFR was reduce to 0.92. The estimated global CFR is 6.34% and 4.05% for the Americas reported by WHO and PAHO, respectively. In this study, 82 patients (10.1%) required intensive care and, of these, 42 (5.5%) were treated with IFN. Conclusions This report provides preliminary evidence for the therapeutic effectiveness of IFN alpha-2b for COVID-19 and suggests that the use of Heberon Alpha R may contribute to complete recovery.

doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.

No abstract