How do the severe acute respiratory coronavirus 2 (SARS-CoV-2) and its variants escape the host protective immunity and mediate pathogenesis?

COVID-19 and Parasitic Co-Infection: A Hypothetical Link to Pulmonary Vascular Disease

Background/Objectives: Before the Coronavirus disease 2019 (COVID-19) era, the global prevalence of pulmonary arterial hypertension (PAH) was between 0.4 and 1.4 per 100,000 people. The long-term effects of protracted COVID-19 associated with pulmonary vascular disease (PVD) risk factors may increase this prevalence. According to preliminary data, the exact prevalence of early estimates places the prevalence of PVD in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection at 22%, although its predictive value remains unknown. PVD caused by COVID-19 co-infections is understudied and underreported, and its future impact is unclear. However, due to COVID-19/co-infection pathophysiological effects on pulmonary vascularization, PVD mortality and morbidity may impose a genuine concern-both now and in the near future. Based on reported studies, this literature review focused on the potential link between COVID-19, parasitic co-infection, and PVD. This review article also highlights hypothetical pathophysiological mechanisms between COVID-19 and parasitic co-infection that could trigger PVD. Methods: We conducted a systematic literature review (SLR) searching peer-reviewed articles, including link between COVID-19, parasitic co-infection, and PVD. Results: This review hypothesized that multiple pathways associated with pathogens such as underlying schistosomiasis, human immunodeficiency virus (HIV), pulmonary tuberculosis (PTB), pulmonary aspergillosis, Wuchereria bancrofti, Clonorchis sinensis, paracoccidioidomycosis, human herpesvirus 8, and scrub typhus coupled with acute or long COVID-19, may increase the burden of PVD and worsen its mortality in the future. Conclusions: Further experimental studies are also needed to determine pathophysiological pathways between PVD and a history of COVID-19/co-infections.

Host Protective Immunity against Severe Acute Respiratory Coronavirus 2 (SARS-CoV-2) and the COVID-19 Vaccine-Induced Immunity against SARS-CoV-2 and Its Variants

The world is now apparently at the last/recovery stage of the COVID-19 pandemic, starting from 29 December 2019, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With the progression of time, several mutations have taken place in the original SARS-CoV-2 Wuhan strain, which have generated variants of concern (VOC). Therefore, combatting COVID-19 has required the development of COVID-19 vaccines using several platforms. The immunity induced by those vaccines is vital to study in order to assure total protection against SARS-CoV-2 and its emerging variants. Indeed, understanding and identifying COVID-19 protection mechanisms or the host immune responses are of significance in terms of designing both new and repurposed drugs as well as the development of novel vaccines with few to no side effects. Detecting the immune mechanisms for host protection against SARS-CoV-2 and its variants is crucial for the development of novel COVID-19 vaccines as well as to monitor the effectiveness of the currently used vaccines worldwide. Immune memory in terms of the production of neutralizing antibodies (NAbs) during reinfection is also very crucial to formulate the vaccine administration schedule/vaccine doses. The response of antigen-specific antibodies and NAbs as well as T cell responses, along with the protective cytokine production and the innate immunity generated upon COVID-19 vaccination, are discussed in the current review in comparison to the features of naturally induced protective immunity.