Background Severe coronavirus disease 2019 (COVID-19) manifests as a life-threatening microvascular syndrome. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses primarily the capsid spike (S) protein to engage with its receptors and infect host cells. To date, it is still not known if the S protein alone, without the other viral elements, is able to trigger vascular cell signalling and provoke cell dysfunction.