The COVID-19 pandemic has had a significant impact on the health and economy of the global population. Even after recovery from the disease, post-COVID-19 symptoms, such as pulmonary fibrosis, continue to be a concern. This narrative review aims to address pulmonary fibrosis (PF) from various perspectives, including the fibrotic mechanisms involved in idiopathic and COVID-19-induced pulmonary fibrosis. On the other hand, we also discuss the current therapeutic drugs in use, as well as those undergoing clinical or preclinical evaluation. Additionally, this article will address various biomarkers with usefulness for PF prediction, diagnosis, treatment, prognosis, and severity assessment in order to provide better treatment strategies for patients with this disease.

Introduction: The COVID-19 pandemic created an urgent need for safe and accessible outpatient treatments. Polymerized type I collagen (PTIC) has demonstrated potential immunomodulatory effects, but its clinical utility in patients with COVID-19 remains underexplored. This study aimed to evaluate the clinical evolution and health outcomes of a cohort of patients with COVID-19 treated with standard medical care plus PTIC during the pandemic emergency, in order to explore its potential role as an adjuvant therapy. Methods: A retrospective cohort study was conducted in 46 outpatients with confirmed COVID-19 treated with PTIC (Fibroquel^®) plus standard care, and 15 controls with standard care alone. Clinical and laboratory data were collected on Days 1 and 10. Patients were stratified by COVID-19 severity and SARS-CoV-2 variant. Analyses included odds ratios and Kaplan–Meier survival curves. Results: Oxygen saturation levels increased significantly from 88.5 ± 5.22 to 95.1 ± 2.07 after PTIC treatment. Supplemental oxygen was required for 26.1% of patients receiving treatment, compared to 60% of those in the untreated group (p < 0.05). Complete recovery was observed in all patients treated with PTIC, compared with 80% recovery in the standard care group. There were no deaths from COVID-19 in the PTIC group. In contrast, 20% of the participants in the untreated group died due to complications from the disease (p = 0.013). PTIC improved the survival rate of patients with the disease. Conclusions: PTIC significantly improved clinical parameters in patients with COVID-19. It improves oxygen saturation levels, decreases the need for supplemental oxygen, and improves survival compared to patients who are not treated with PTIC. Additional studies are needed to validate the use of PTIC as an adjunctive therapy for patients with COVID-19.