Cell-mediated and humoral adaptive immune responses to SARS-CoV-2 are lower in asymptomatic than symptomatic COVID-19 patients.

The characterization of cell-mediated and humoral adaptive immune responses to SARS-CoV-2 is fundamental to understand COVID-19 progression and the development of immunological memory to the virus. In this study, we detected T-cells reactive to SARS-CoV-2 proteins M, S, and N, as well as serum virus-specific IgM, IgA, IgG, in nearly all SARS-CoV-2 infected individuals, but not in healthy donors. Virus-reactive T cells exhibited signs of in vivo activation, as suggested by the surface expression of immune-checkpoint molecules PD1 and TIGIT. Of note, we detected antigen-specific adaptive immune response both in asymptomatic and symptomatic SARS-CoV-2 infected subjects. More importantly, symptomatic patients displayed a significantly higher magnitude of both cell-mediated and humoral adaptive immune response to the virus, as compared to asymptomatic individuals. These findings suggest that an uncontrolled adaptive immune response contribute to the development of the life-threatening inflammatory phase of the disease. Finally, this study might open the way to develop effective vaccination strategies.

Antiviral combination regimens as rescue therapy in immunocompromised hosts with persistent COVID-19.

The management of severe/prolonged SARS-CoV-2 infections in immunocompromised hosts is still challenging. We describe nine patients with hematologic malignancies with a history of unsuccessful SARS-CoV-2 treatment receiving antiviral combination treatment for persistent infection at a tertiary hospital in central Italy (University Hospital of Careggi, Florence). Combination treatments consisted of nirmatrelvir/ritonavir plus molnupiravir (n = 4), nirmatrelvir/ritonavir plus remdesivir (n = 4) or remdesivir plus molnupiravir (n = 1) for 10 days, in some cases associated with sotrovimab. Combinations were generally well tolerated. One patient obtained viral clearance but died due to the underlying disease. In eight cases, clinical and virological success was confirmed by radiological follow-up. Antivirals combination is likely to become a mainstay in the future management of COVID-19 among immunocompromised patients, but knowledge in this field is still very limited and prospective studies on larger cohorts are urgently warranted.

Use of the FebriDx point-of-care test for the exclusion of SARS-CoV-2 diagnosis in a population with acute respiratory infection during the second (COVID-19) wave in Italy.

OBJECTIVE: Evaluate the real-world accuracy of Myxovirus resistance protein A (MxA) detected by the rapid, point-of-care FebriDx test during the second-wave pandemic in Italy in patients with acute respiratory infection (ARI) and a clinical suspicion of COVID-19. DESIGN AND METHODS: Prospective, observational, diagnostic accuracy study whereby hospitalized patients with ARI were consecutively enrolled in a single tertiary care center in Italy from August 1, 2020 to January 31, 2021. RESULTS: COVID-19 was diagnosed in 136/200 (68.0%) patients and Non-COVID-19 was diagnosed in 64/200 (32.0%) patients. COVID-19 patients were younger and had a lower Charlson comorbidity index compared to Non-COVID-19 patients (p < 0.001). Concordance between FebriDx, MxA and rt-PCR for SARS-CoV-2 (gold standard) was good (k 0.93, 95% CI 0.87-0.99). Overall sensitivity and specificity were 97.8% [95% CI 93.7-99.5] and 95.3% [95% CI 86.9%-99.0%], respectively. FebriDx demonstrated a negative predictive value of 95.3% (95% CI 86.9-99.0) for an observed disease prevalence of 68%. CONCLUSIONS: FebriDx MxA showed high diagnostic accuracy to identify COVID-19 and could be considered as a real-time triage tool to streamline the management of suspected COVID-19 patients. FebriDx also detected bacterial etiology in Non-COVID-19 patients suggesting good performance to distinguish bacterial from viral respiratory infection.