Heterologous booster immunization with SARS-CoV-2 spike protein after mRNA vaccine elicits durable and broad antibody responses (preprint)

Although mRNA vaccines are more immunogenic than other vaccine modalities in primary series vaccination, their immunogenicity has not been well compared to different vaccine modalities in additional boosters. Here the longitudinal analysis reveals more sustained RBD-binding IgG titers and RBD-ACE2 binding inhibitory activities with the breadth to antigenically distinct Beta and Omicron BA.1 variants by the S-268019-b spike protein booster vaccination compared to BNT162b2 mRNA homologous booster on mRNA vaccinees. The differences in the durability and breadth of plasma antibodies between BNT162b2 and S-268019-b groups are pronounced in those without systemic adverse events and were associated with different trends in the number and breadth of memory B cells. High-dimensional immune profiling identifies early CD16 + natural killer cell dynamics with CCR3 upregulation, as one of the correlates for the distinct antibody responses by the S-268019-b booster. Our results illustrate the combinational effects of heterologous booster on the immune dynamics and the durability and breadth of recalled antibody responses against emerging virus variants.

Phase 3, multicentre, double-blind, randomised, parallel-group, placebo-controlled study of camostat mesilate (FOY-305) for the treatment of COVID-19 (CANDLE study) (preprint)

Background: In vitro drug-screening studies have indicated that camostat mesilate (FOY-305) may prevent SARS-CoV-2 infection into human airway epithelial cells. This study was conducted to investigate whether camostat mesilate is an effective treatment for SARS-CoV-2 infection (COVID-19). Methods: This was a phase 3, multicentre, double-blind, randomised, parallel-group, placebo-controlled study. Patients were enrolled if they were admitted to a hospital within 5 days of onset of COVID-19 symptoms or within 5 days of a positive test for asymptomatic patients. Severe cases (e.g., those requiring oxygenation/ventilation) were excluded. Patients were administered camostat mesilate (600 mg qid; four to eight times higher than the clinical doses in Japan) or placebo for up to 14 days. The primary efficacy endpoint was the time to the first two consecutive negative tests for SARS-CoV-2. Findings: One-hundred and fifty-five patients were randomised to receive camostat mesilate (n=78) or placebo (n=77). The median time to the first test was 11 days in both groups, and conversion to negative status was observed in 60.8% and 63.5% of patients in the camostat mesilate and placebo groups, respectively. The primary (Bayesian) and secondary (frequentist) analyses found no significant differences in the primary endpoint between the two groups. No additional safety concerns beyond those already known for camostat mesilate were identified. Interpretation: Camostat mesilate is no more effective, based on upper airway viral clearance, than placebo for treating patients with mild to moderate SARS-CoV-2 infection with or without symptoms. Funding: Ono Pharmaceutical Co., Ltd.

Immunogenicity and Safety of Booster Dose of S-268019-b or Tozinameran in Japanese Participants: An Interim Report of Phase 2/3, Randomized, Observer-Blinded, Noninferiority Study (preprint)

In this randomized, observer-blinded, phase 2/3 study, S-268019-b (n=101), a recombinant spike protein vaccine, was analyzed for noninferiority versus tozinameran (n=103), when given as a booster ≥6 months after 2-dose tozinameran regimen in Japanese adults without prior COVID-19 infection. Interim results showed noninferiority of S-268019-b versus tozinameran in co-primary endpoints for neutralizing antibodies on day 29: geometric mean titer (GMT) (124.97 versus 109.70; adjusted-GMT ratio [95% CI], 1.14 [0.94-1.39]; noninferiority P -value, <0.0001) and seroresponse rate (both 100%; noninferiority P -value, 0.0004). Both vaccines elicited anti-spike-protein immunoglobulin G antibodies, and produced T-cell response (n=29/group) and neutralizing antibodies against Delta and Omicron pseudovirus and live virus variants (n=24/group) in subgroups. Most participants reported low-grade reactogenicity on days 1-2, the most frequent being fatigue, fever, myalgia, and injection-site pain. No serious adverse events were reported. In conclusion, S-268019-b was safe and showed robust immunogenicity as a booster, supporting its use as COVID-19 booster vaccine. JRCT ID jRCT2031210470 Highlights Third COVID-19 vaccine dose (booster) enhances immune response Interim phase 2/3 data for booster ≥6 months after the 2nd dose in Japan are shown S-268019-b was noninferior to tozinameran in inducing neutralizing antibodies Sera boosted with either vaccines neutralized Delta and Omicron virus variants S-268019-b was safe, and results support its use as a booster in vaccinated adults

Factors Associated with Low IgG Response to mRNA COVID-19 Vaccine BNT162b2 (preprint)

Amid pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), vaccination is hailed as one of the most effective preventive measures. An mRNA vaccine termed BNT162b2 showed satisfactory safety and efficacy in the clinical trials but several issues including variability in the individual immune response or determination of target antibody titre that exerts sufficient immune protection needs to be assessed for planning a more efficient vaccination strategy. By monitoring IgG titres before and two months after the initial administration of BNT162b2 in 655 healthcare workers by Abbott IgG II quant that detects IgG against the receptor-binding domain in S protein of SARS-CoV-2, we confirmed that hypertension, dyslipidaemia, chronic kidney disease and use of immune suppressant in addition to male gender, advanced age, and absence of previous infection were significantly associated with low antibody response to the vaccination.

Prognostic Predictors For COVID-19 in Daily Clinical Practice in Japan: a Propensity Score-Matched Case-Control Study (preprint)

Introduction: Blood tests and computed tomography (CT) findings at diagnosis are widely used in daily clinical practice and can offer useful prognostic factors for coronavirus disease 2019. Methods: : We retrospectively evaluated 66 patients who underwent a blood test and CT between January 1 and May 31, 2020, and performed a propensity score-matched case-control study. Cases and controls were a severe respiratory failure group (non-rebreather mask, nasal high-flow, positive-pressure ventilation) and a non-severe respiratory failure group, matched at a ratio of 1:3 by propensity scores constructed by age, sex, and medical history. We compared groups for maximum body temperature up to diagnosis, laboratory findings, and CT findings in the matched cohort. Two-tailed P-values <0.05 were considered statistically significant. Results: : Nine cases and 27 controls were included in the matched cohort. Significant differences were seen in maximum body temperature up to diagnosis (p=0.0043), the number of shaded lobes (p=0.0434), amount of ground-glass opacity (GGO) in the total lung field (p=0.0071), amounts of GGO (p=0.0001), and consolidation (p=0.0036) in the upper lung field, and pleural effusion (p=0.0117). Conclusions: : Fever and CT findings (such as GGO and consolidation) may be prognostic indicators that can be easily measured at diagnosis.

Corticosteroids for hospitalized patients with mild to critically-ill COVID-19: A multicenter, retrospective, propensity score–matched study (preprint)

Background: Corticosteroids use in coronavirus disease 2019 (COVID-19) is controversial, especially in mild to severe patients who do not require invasive/noninvasive ventilation. Moreover, many factors remain unclear regarding the appropriate use of corticosteroids for COVID-19. In this context, this multicenter, retrospective, propensity score–matched study was launched to evaluate the efficacy of systemic corticosteroid administration for hospitalized patients with COVID-19 ranging in the degree of severity from mild to critically-ill disease.Methods: This multicenter, retrospective study enrolled consecutive hospitalized COVID-19 patients diagnosed January–April 2020 across 30 institutions in Japan. Clinical outcomes were compared for COVID-19 patients who received or did not receive corticosteroids, after adjusting for propensity scores. The primary endpoint was the odds ratio (OR) for improvement on a 7-point ordinal score on Day 15.Results: Of 1092 COVID-19 patients analyzed, 118 patients were assigned to either the corticosteroid and non-corticosteroid group, after propensity score matching. At baseline, most patients did not require invasive/noninvasive ventilation (85.6% corticosteroid group vs. 89.8% non-corticosteroid group). The odds of improvement in a 7-point ordinal score on Day 15 was significantly lower for the corticosteroid versus non-corticosteroid group (OR, 0.611; 95% confidence interval [CI], 0.388–0.962; p = 0.034). The time to improvement in radiological findings was significantly shorter in the corticosteroid versus non-corticosteroid group (hazard ratio [HR], 1.758; 95% CI, 1.323–2.337; p < 0.001), regardless of baseline clinical status. The duration of invasive mechanical ventilation was shorter in corticosteroid versus non-corticosteroid group (HR, 1.466; 95% CI, 0.841–2.554; p = 0.177). Of the 106 patients who received methylprednisolone, the duration of invasive mechanical ventilation was significantly shorter in the pulse/semi-pulse versus standard dose group (HR, 2.831; 95% CI, 1.347–5.950; p = 0.006).Conclusions: Corticosteroids for hospitalized patients with COVID-19 did not improve clinical status on Day 15, but reduced the time to improvement in radiological findings for all patients regardless of disease severity and also reduced the duration of invasive mechanical ventilation in patients who required intubation.Trial registration: This study was registered in the University hospital Medical Information Network Clinical Trials Registry on April 21, 2020 (ID: UMIN000040211).