Emulation of a target trial from observational data to compare effectiveness of Casirivimab/Imdevimab and Bamlanivimab/Etesevimab for early treatment of non-hospitalized patients with COVID-19 (preprint)

Objectives Comparative analysis between different monoclonal antibodies (mAbs) against SARS-CoV-2 are lacking. We present an emulation trial from observational data to compare effectiveness of Bamlanivimab/Etesevimab (BAM/ETE) and Casirivimab/Imdevimab (CAS/IMD) in outpatients with early mild-to-moderate COVID-19 in a real-world scenario of variants of concern (VoCs) from Alpha to Delta. Methods Allocation to treatment was subject to mAbs availability, and the measured factors were not used to determine which combination to use. Patients were followed through day 30. Viral load was measured by cycle threshold (CT) on D1 (baseline) and D7. Primary outcome was time to COVID-19-related hospitalization or death from any cause over days 0-30. Weighted pooled logistic regression and marginal structural Cox model by inverse probability weights were used to compare BAM/ETE vs. CAS/IMD. ANCOVA was used to compare mean D7 CT values by intervention. Models were adjusted for calendar month, MASS score and VoCs. We evaluated effect measure modification by VoCs, vaccination, D1 CT levels and enrolment period. Results COVID19-related hospitalization or death from any cause occurred in 15 of 237 patients in the BAM/ETE group (6.3%) and in 4 of 196 patients in the CAS/IMD group (2.0%) (relative risk reduction [1 minus the relative risk] 72%; p=0.024). Subset analysis carried no evidence that the effect of the intervention was different across stratification factors. There was no evidence in viral load reduction from baseline through day 7 across the two groups (+0.17, 95% -1.41;+1.74, p=0.83). Among patients who experienced primary outcome, none showed a negative RT-PCR test in nasopharingeal swab (p=0.009) and 82.4% showed still high viral load (p<0.001) on D7. Conclusions In a pre-Omicron epidemiologic scenario, CAS/IMD reduced risk of clinical progression of COVID-19 compared to BAM/ETE. This effect was not associated with a concomitant difference in virological response.

Retention of Neutralizing response against SARS-CoV-2 Omicron variant in Sputnik V vaccinated individuals (preprint)

The new variant Omicron (B.1.1.529) of SARS-CoV-2, first identified in November 2021, is rapidly spreading all around the world. The Omicron becomes the dominant variant of SARS-CoV-2. There are many ongoing studies evaluating the effectiveness of existing vaccines. Studies on neutralizing activity of vaccinated sera against Omicron variant are currently being carried out in many laboratories. In this study, we have shown the neutralizing activity of sera against SARS-CoV-2 Omicron (B.1.1.529) variant compared to the reference Wuhan D614G (B.1) variant in individuals vaccinated with 2 doses of Sputnik V or BNT162b2 in different time points up to 6 months after vaccination. We performed analysis on sample pools with comparable NtAb to Wuhan D614G variant. The decrease in neutralizing antibody (NtAb) to the Omicron variant was 8.1 folds for group of Sputnik V-vaccinated and 21.4 folds for group of BNT162b2-vaccinated. Analysis showed that 74.2% of Sputnik V- and 56.9% of BNT162b2-vaccinated sera had detectable NtAb to SARS-CoV-2 Omicron variant. The decrease in NtAb to SARS-CoV-2 Omicron variant compared to Wuhan variant has been shown for many COVID-19 vaccines in use, with some showing no neutralization at all. Today the necessity of third booster vaccination is obvious. And the most effective approach, already shown in several studies, is the use of heterologous booster vaccination pioneered in COVID-19 vaccines by Sputnik V.

Virological and Serological Characterization of SARS-CoV-2 Infections Diagnosed After mRNA BNT162b2 Vaccination. (preprint)

Coronavirus disease 2019 (COVID-19) vaccines are proving to be very effective in preventing severe illness; however, although rare, post-vaccine infections have been reported. The present study describes 94 infections (47.9% symptomatic, 52.1% asymptomatic), occurred in Lazio Region (Central Italy) in the first trimester 2021, after first or second dose of mRNA BNT162b2 vaccine. Median viral load at diagnosis was independent from number and time of vaccine dose administration, despite the higher proportion of samples with low viral load observed in fully vaccinated individuals. More importantly, infectious virus was cultured from NPS collected from both asymptomatic and symptomatic vaccinated individuals, suggesting that, at least in principle, they can transmit the infection to susceptible people. The majority of the post-vaccine infections here reported, showed pauci/asymptomatic clinical course, confirming the impact of vaccination on COVID-19 disease. Most cases (78%) showed infection in presence of neutralizing antibodies at the time of infection diagnosis, presumably attributable to vaccination, due to the concomitant absence of anti-N IgG in most cases. The proportion of post-vaccine infections attributed either to Alpha and Gamma VOCs was similar to the proportion observed in the contemporary unvaccinated population in Lazio region. In addition, mutational analysis did not suggest enrichment of a defined set of Spike protein substitutions depending on the vaccination status. Characterization of host and virus factors associated with vaccine breakthrough, coupled with intensive and continuous monitoring of involved viral strains, is crucial to adopt informed vaccination strategies.

SARS-CoV-2 cytopathogenesis in cultured cells and in COVID-19 autoptic lung, evidences of lipid involvement. (preprint)

Background: The pathogenesis of SARS-CoV-2 remains to be defined. Elucidating SARS-CoV-2 cellular localization within cells and its cytopathic effects requires definition. We performed a comparative ultrastructural study of SARS-CoV-2 infection of Vero-6 cells and lung from COVID-19 patients. Main findings: SARS-CoV-2 induces rapid ultrastructural changes and death in Vero cells. Ultrastructural changes in SARS-CoV-2 infection differ from those in SARS-CoV-1.  Type II pneumocytes in lung tissue showed prominent altered morphological features with numerous vacuoles and swollen mitochondria with presence of abundant lipid droplets. The accumulation of lipid droplets was the most striking finding we observed in cultured cells and in infected pneumocytes. Virus particles were also found associated with lipo-lysosomes suggesting that they can play an important step in virus assembly.Interpretation: The cytopathology of SARS-CoV-2 appears to be different to that caused by SARS-CoV-1. Our findings highlight important open topics which may represent future targets to contrast the pathogenicity of SARS-CoV-2. 

Synthetic Antibodies neutralize SARS-CoV-2 infection of mammalian cells (preprint)

Coronaviruses (CoV) are a large family of enveloped, RNA viruses that circulate in mammals and birds. Three highly pathogenic strains have caused zoonotic infections in humans that result in severe respiratory syndromes including the Middle East Respiratory Syndrome CoV (MERS), Severe Acute Respiratory Syndrome CoV (SARS), and the ongoing Coronavirus Disease 2019 (COVID-19) pandemic. Here, we describe a panel of synthetic monoclonal antibodies, built on a human IgG framework, that bind to the spike protein of SARS-CoV-2 (the causative agent of COVID-19), compete for ACE2 binding, and potently inhibit SARS-CoV-2. All antibodies that exhibited neutralization potencies at sub-nanomolar concentrations against SARS-CoV-2/USA/WA1 in Vero E6 cells, also bound to the receptor binding domain (RBD), suggesting competition for the host receptor ACE2. These antibodies represent strong immunotherapeutic candidates for treatment of COVID-19.

Evaluation of ELISA tests for the qualitative determination of IgG, IgM and IgA to SARS-CoV-2 (preprint)

Serological assays for anti-SARS-CoV-2 antibodies are now of critical importance to support diagnosis, guide epidemiological intervention, and understand immune response to natural infection and vaccine administration. We developed and validated new anti-SARS-CoV-2 IgG, IgM and IgA ELISA tests (ENZY-WELL SARS-CoV-2 ELISA, DIESSE Diagnostica Senese S.p.a.) based on whole-virus antigens. We used a total of 553 serum samples including samples from COVID-19 suspected and confirmed cases, healthy donors, and patients positive for other infections or autoimmune conditions. Overall, the assays showed good concordance with the indirect immunofluorescence reference test in terms of sensitivity and specificity. Especially for IgG and IgA, we observed high sensitivity (92.5 and 93.6%, respectively); specificity was high (>96%) for all antibody types ELISAs. In addition, sensitivity was linked to the days from symptoms onset (DSO) due to the seroconversion window, and for ENZY-WELL SARS-CoV-2 IgG and IgA ELISAs resulted 100% in those samples collected after 10 and 12 DSO, respectively. The results showed that ENZY-WELL SARS-CoV-2 ELISAs may represent a valid option for both diagnostic and epidemiological purposes, covering all different antibody types developed in SARS-CoV-2 immune response.