Impact of vaccination on the presence and severity of symptoms in hospitalized patients with an infection of the Omicron variant (B.1.1.529) of the SARS-CoV-2 (subvariant BA.1).

OBJECTIVES: The emergence of SARS-CoV-2 variants raised questions about the extent to which vaccines designed in 2020 have remained effective. We aimed to assess whether vaccine status was associated with the severity of Omicron SARS-CoV-2 infection in hospitalized patients. METHODS: We conducted an international, multi-centric, retrospective study in 14 centres (Bulgaria, Croatia, France, and Turkey). We collected data on patients hospitalized for ≥24 hours between 1 December 2021 and 3 March 2022 with PCR-confirmed infection at a time of exclusive Omicron circulation and hospitalization related or not related to the infection. Patients who had received prophylaxis by monoclonal antibodies were excluded. Patients were considered fully vaccinated if they had received at least two injections of either mRNA and/or ChAdOx1-S or one injection of Ad26.CoV2-S vaccines. RESULTS: Among 1215 patients (median age, 73.0 years; interquartile range, 57.0-84.0; 51.3% men), 746 (61.4%) were fully vaccinated. In multivariate analysis, being vaccinated was associated with lower 28-day mortality (Odds Ratio [95% Confidence Interval] (OR [95CI]) = 0.50 [0.32-0.77]), intensive care unit admission (OR [95CI] = 0.40 [0.26-0.62]), and oxygen requirement (OR [95CI] = 0.34 [0.25-0.46]), independent of age and comorbidities. When co-analysing these patients with Omicron infection with 948 patients with Delta infection from a study we recently conducted, Omicron infection was associated with lower 28-day mortality (OR [95CI] = 0.53 [0.37-0.76]), intensive care unit admission (OR [95CI] = 0.19 [0.12-0.28]), and oxygen requirements (OR [95CI] = 0.50 [0.38-0.67]), independent of age, comorbidities, and vaccination status. DISCUSSION: Originally designed vaccines have remained effective on the severity of Omicron SARS-CoV-2 infection. Omicron is associated with a lower risk of severe forms, independent of vaccination and patient characteristics.

Impact of vaccination on the symptoms of hospitalised patients with SARS-CoV-2 Delta variant (B.1.617.1) infection.

OBJECTIVES: The diffusion of the SARS-CoV-2 Delta (B.1.617.2) variant and the waning of immune response after primary Covid-19 vaccination favoured the breakthrough SARS-CoV-2 infections in vaccinated subjects. To assess the impact of vaccination, we determined the severity of infection in hospitalised patients according to vaccine status. METHODS: We performed a retrospective observational study on patients hospitalised in 10 centres with a SARS-CoV-2 infection (Delta variant) from July to November 2021 by including all patients who had completed their primary vaccination at least 14 days before hospital admission and the same number of completely unvaccinated patients. We assessed the impact of vaccination and other risk factors through logistic regression. RESULTS: We included 955 patients (474 vaccinated and 481 unvaccinated). Vaccinated patients were significantly older (75.0 [63.25-84.0] vs. 55.0 [38.0-73.0]; p < 0.001), more frequently males (55.1% (261/474) vs. 46.4% (223/481); p = 0.009), and had more comorbidities (2.0 [1.0-3.0] vs. 1.0 [0.0-2.0]; p < 0.001). Vaccinated patients were less often admitted for Covid-19 (59.3% (281/474) vs. 75.1% (361/481); p < 0.001), had less extended lung lesions (≤25%: 64.3% (117/182) vs. 38.4% (88/229); p < 0.001), required oxygen less frequently (57.5% (229/398) vs. 73.0% (270/370); p < 0.001), at a lower flow (3.0 [0.0-8.7] vs. 6.0 [2.0-50.0] L/min, p < 0.001), and for a shorter duration (3 [0.0-8.0] vs. 6 [2.0-12.0] days, p < 0.001)., and required less frequently intensive care unit admission (16.2% (60/370) vs. 36.0% (133/369); p < 0.001) but had comparable mortality in bivariate analysis (16.7% (74/443) vs. 12.2% (53/433); p = 0.075). Multivariate logistic regression showed that vaccination significantly decreased the risk of death (0.38 [0.20-0.70](p = 0.002), ICU admission (0.31 [0.21-0.47](p < 0.001) and oxygen requirement (0.16 [0.10-0.26](p < 0.001), even among older patients or with comorbidities. CONCLUSIONS: Among patients hospitalised with a delta variant SARS-CoV-2 infection, vaccination was associated with less severe forms, even in the presence of comorbidities.

Humoral response to a third injection of BNT162b2 vaccine in patients on maintenance haemodialysis.

BACKGROUND: Humoral response against sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after two doses of BNT162b2 (Pfizer-BioNTech) has been proven to be less intense in maintenance dialysis patients as compared with healthy subjects, leading the French authorities to recommend a third injection in this population. Here we investigated the response to the third injection in two cohorts of haemodialysis (HD) patients. METHODS: Data from two prospective observational cohorts were collected. In the first ('systematic') cohort, patients from two HD centres (n = 66) received a third injection of BNT162b2, regardless of the response after two injections. In the second ('conditional') cohort, the injection was only prescribed to patients (n = 34) with no or low response to the previous two doses. In both cohorts, the third dose was injected 1-2 months after the second dose. Serology was performed after the second and third doses to assess anti-Spike immunoglobulin G (S IgG) antibody titre. RESULTS: In the systematic cohort, anti-S IgG was found in 83.3 and 92.4% of patients after the second and third doses of BNT162b2, respectively. In this cohort, 6/11 (54.5%) and 20/21 (95.2%) patients switched from non-responder to low responder and from low responder to high responder, respectively. In low and high responders to two doses, 50/55 (90.9%) at least doubled their anti-S IgG titre. Similar trends were observed in the conditional cohort. CONCLUSIONS: In maintenance HD patients, humoral response against SARS-CoV-2 was boosted after a third dose of BNT162b2, allowing seroconversion in more than half of non-responders. These data may support an intensified vaccination protocol with a third dose of BNT162b2 in dialysis patients.

COVID-19 Vaccine Hesitancy in Patients on Dialysis in Italy and France.

INTRODUCTION: Patients on dialysis (HDPs) are a category at high risk from COVID-19 and thus a high-priority group for vaccination. COVID-19 vaccine hesitancy has been a concern since the availability of the first vaccine. The objective of this study was to determine hesitancy rates and factors associated with hesitancy toward COVID-19 vaccination in HDP. METHODS: HDP were surveyed with an ad hoc questionnaire in 4 large dialysis facilities in Europe: Le Mans and Paris, in France, and Cagliari and Pavia, in Italy. The questionnaire explored different domains associated with vaccine hesitancy, such as perception of disease severity, sources of information about the vaccine and the disease, and confidence in the health care system. RESULTS: A total of 417 patients (average age 69 years, 60% men) agreed to answer the questionnaire. Hesitancy was associated with younger age (P = 0.003), lower perception of disease severity (P < 0.001) and vaccine efficacy (P < 0.001), and lower trust in vaccination (P < 0.001) and in the health care system and scientists (P < 0.001) in the univariate analysis. In the multivariate models, concerns about side effects (P = 0.004) and vaccine efficacy (P < 0.001) and living in France (P = 0.04) remained associated with higher vaccine hesitancy, whereas having received an influenza vaccine (P = 0.032) and trusting scientists (P = 0.032) were associated with a more positive attitude toward vaccination. CONCLUSIONS: HDPs have a good understanding of the risks associated with COVID-19. Vaccine hesitancy was not associated with educational level, age, or gender but rather with lack of confidence in vaccine efficacy and concerns about safety. HDPs were quite skeptical about the health care system but generally trusted scientists.