Immunogenicity and safety of a recombinant adenovirus type-5 COVID-19 vaccine in adults: Data from a randomised, double-blind, placebo-controlled, single-dose, phase 3 trial in Russia.

BACKGROUND: To determine the immunogenicity, efficacy, reactogenicity, and safety of a single dose of recombinant adenovirus type-5 vectored COVID-19 vaccine (Ad5-nCoV, 5 × 1010 viral particles per 0.5 mL dose), we conducted a single-dose, randomised, double-blind, placebo-controlled, parallel group (3:1 Ad5-nCoV:placebo), phase 3 trial (Prometheus). METHODS: From 11-September-2020 to 05-May-2021, across six sites in the Russian Federation, 496 participants were injected with either placebo or Ad5-nCoV expressing the full-length spike (S) protein from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). RESULTS: Seroconversion (the primary endpoint) rates of 78.5% (95% CI: 73.9; 82.6) against receptor binding domain (RBD), 90.6% (95% CI: 87.2; 93.4) against S protein and 59.0% (95% CI: 53.3; 64.6) seroconversion of neutralising antibodies against SARS-CoV-2 at 28 days post-vaccination were observed. Geometric mean titres (GMTs) were also elevated for antibodies against the RBD (405 [95% CI: 366; 449]) and S protein (677 [95% CI: 608; 753]) compared to the GMT of neutralising antibodies against SARS-CoV-2 (16.7 [95% CI: 15.3; 18.3]). Using an IFN-γ ELISpot assay after stimulating the cells with recombinant S protein ectodomain we showed that the Ad5-nCoV vaccine induced the most robust cellular immune response on Days 14 and 28. Up to Day 28, the primary and all secondary endpoints of the Ad5-nCoV vaccine were statistically significant compared with the placebo (р<0.001). Systemic reactions were reported in 113 of 496 (22.8%) participants (Ad5-nCoV, 26.9%; Placebo, 10.5%), and local reactions were reported in 108 (21.8%) participants (Ad5-nCoV, 28.5%; Placebo, 1.6%). These were generally mild and resolved within 7 days after vaccination. Of the six serious adverse events reported, none of the events were vaccine related. There were no deaths or premature withdrawals. CONCLUSION: A single-dose of Ad5-nCoV vaccine induced a marked specific humoral and cellular immune response with a favourable safety profile. TRIAL REGISTRATION: Trial registration: ClinicalTrials.gov: NCT04540419.

Open-label use of an aliphatic polyamine immunomodulator in patients hospitalized with COVID-19.

Background: Evidence-based therapies used to treat coronavirus disease (COVID-19) remain limited. Azoximer bromide (AZB; Polyoxidonium®) is an immunomodulating molecule frequently used in the Russian Federation. It offers demonstrable therapeutic benefit in upper respiratory tract infections. This study evaluated the safety and efficacy of AZB when used in combination with standard of care treatment in patients hospitalized with COVID-19. Methods: Hospitalized patients with COVID-19 (n=81; nine sites) received AZB 12 mg intravenously once daily for 3 days then intramuscularly every other day until day 17. The primary endpoint included clinical status at day 15 versus baseline. Historical control data of 100 patients from a randomized, controlled, open-label trial conducted in China were included to serve as a direct control group. Results: Notable clinical improvement, assessed by seven-point ordinal scale (OS) score and National Early Warning Score, was observed. Mean duration of hospitalization was 19.3 days. Indicators of pneumonia and lung function showed gradual recovery to normalization. No patients died but, by day 28, one patient still required respiratory support; this patient died on day 34. A higher proportion of patients receiving AZB required invasive or non-invasive ventilation (OS 5 or 6) at baseline compared with the historical control group. Improvement in mean OS score by day 14/15 was not notable in the control group (OS 3.99-3.87) but was clear in the AZB group (OS 4.36-2.90). Mean duration of hospitalization was similar in the control group (16.0 days); however, day 28 mortality was higher, at 25.0% (n=25). Conclusion: AZB combined with standard of care was safe and well tolerated. An apparent clinical improvement could not be fully evaluated due to the lack of a direct control group; further assessment of AZB for the treatment of COVID-19 in a randomized, placebo-controlled study is warranted.

The effect of azoximer bromide (Polyoxidonium®) in patients hospitalized with coronavirus disease (COVID-19): an open-label, multicentre, interventional clinical study.

A clinical need for aetiotropic coronavirus disease (COVID-19) treatments is required. The immune modulator azoximer bromide (AZB; Polyoxidonium®) is indicated in Russia for use against acute viral infections and during remission. In this study, adults hospitalized with COVID-19 (n=32) received AZB and standard of care in an open-label, multicentre, interventional study. All patients were symptomatic; 22 had severe disease (National Early Warning Score ≥5) and required mechanical ventilation or oxygen saturation (SpO2) and 19 patients had co-morbidities. Patients received AZB 12 mg intravenously once daily for 3 days, then intramuscularly every other day (approximately ten injections) until discharge. The primary endpoint was the patient's clinical status (7-point Ordinal Scale; OS) on day 15 versus that at baseline. The mean duration of hospitalization was 20 days. All patients were alive and discharged with normal SpO2 with no secondary infections or delayed mortality reported by the end-of-study visit (on day 28-72). A decrease in the mean OS and National Early Warning Score values was observed following treatment with AZB. A decrease in OS score was marked in patients identified as severe. Both sets of patients achieved similar scores, which can be classified as an improvement by day 9-10; SpO2 levels trended to normalization over time. By day 11-12, all patients had a normal body temperature. Serum C-reactive protein levels decreased in patients with severe and mild disease. Most patients had signs of pneumonia at baseline (n=27), with the majority recovering by days 10-12. No major toxicities were observed. AZB was safe and well tolerated when administered in addition to standard of care treatment for COVID-19. Further randomized, placebo-controlled studies are needed to elucidate any potential therapeutic effect in COVID-19.