The induction of effective cellular and humoral immune responses against antigens is the major goal in vaccination strategies against infectious diseases and cancer. In this review, we will discuss influenza virosomes as a versatile delivery system for molecules of a different nature, such as proteins, peptides and nucleic acids. These molecules can be administered in different ways, such as nasal, muscular or dermal routes, also facilitating the uptake of the antigen by antigen-presenting cells (APC) and inducing a specific humoral and cell-mediated immune response, particularly a CTL response. Influenza virosomes, due to their applicability in different medical fields, are a promising tool in vaccinology and immunotherapy applications.

SARS-CoV2-induced direct cytopathic effects against type II pneumocytes are suspected to play a role in mediating and perpetuating lung damage. The aim of this study was to evaluate serum KL-6 behavior in COVID-19 patients to investigate its potential role in predicting clinical course. Sixty patients (median age IQR, 65 (52–69), 43 males), hospitalized for COVID-19 at Siena COVID Unit University Hospital, were prospectively enrolled. Twenty-six patients were selected (median age IQR, 63 (55–71), 16 males); all of them underwent follow-up evaluations, including clinical, radiological, functional, and serum KL-6 assessments, after 6 (t1) and 9 (t2) months from hospital discharge. At t0, KL-6 concentrations were significantly higher than those at t1 (760 (311–1218) vs. 309 (210–408) p = 0.0208) and t2 (760 (311–1218) vs 324 (279–458), p = 0.0365). At t0, KL-6 concentrations were increased in patients with fibrotic lung alterations than in non-fibrotic group (755 (370–1023) vs. 305 (225–608), p = 0.0225). Area under the receiver operating curve (AUROC) analysis showed that basal KL-6 levels showed good accuracy in discriminating patients with fibrotic sequelae radiologically documented (AUC 85%, p = 0.0404). KL-6 concentrations in patients with fibrotic involvement were significantly reduced at t1 (755 (370–1023) vs. 290 (197–521), p = 0.0366) and t2 (755 (370–1023) vs. 318 (173–435), p = 0.0490). Serum concentrations of KL-6 in hospitalized COVID-19 patients may contribute to identify severe patients requiring mechanical ventilation and to predict those who will develop pulmonary fibrotic sequelae in the follow-up.

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