Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing the current pandemic of coronavirus disease 2019 (COVID-19), and COVID-19 vaccines focus on its spike protein. However, in addition to facilitating the membrane fusion and viral entry, the SARS-CoV-2 spike protein promotes cell growth signaling in human lung vascular cells, and patients who died of COVID-19 have thickened pulmonary vascular walls, linking the spike protein to a fatal disease, pulmonary arterial hypertension (PAH). In addition to SARS-CoV spike proteins, gp120, the viral membrane fusion protein of HIV, has been reported to promote cell signaling, and long-term surviving HIV-positive patients have a high incidence of developing PAH. This article describes the finding of the SARS-CoV-2 spike protein affecting lung vascular cells and explains how the spike protein possibly increases the incidence of PAH. Since the SARS-CoV-2 spike protein will be administered to millions of people as COVID-19 vaccines, it is critical to understand the biological effects of this protein on human cells to ensure that it does not promote long-term adverse health consequences.

1. Introduction
2. The SARS-CoV-2 spike protein activates cell signaling in lung vascular cells
3. Pathology of PAH
4. Do the membrane fusion proteins of other viruses also activate cell signaling in host cells without the rest of the viral components?
5. HIV increases the incidence of PAH
6. Are individuals infected with SARS-CoV-2 predisposed to developing PAH?
7. COVID-19 vaccines and PAH
8. Conclusions