Quality, availability and suitability of antimicrobial stewardship guidance: a multinational qualitative study.

Background: Antimicrobial stewardship (AMS) programmes are established across the world to treat infections efficiently, prioritize patient safety, and reduce the emergence of antimicrobial resistance. One of the core elements of AMS programmes is guidance to support and direct physicians in making efficient, safe and optimal decisions when prescribing antibiotics. To optimize and tailor AMS, we need a better understanding of prescribing physicians' experience with AMS guidance. Objectives: To explore the prescribing physicians' user experience, needs and targeted improvements of AMS guidance in hospital settings. Methods: Semi-structured interviews were conducted with 36 prescribing physicians/AMS guidance users from hospital settings in Canada, Germany, Israel, Latvia, Norway and Sweden as a part of the international PILGRIM trial. A socioecological model was applied as an overarching conceptual framework for the study. Results: Research participants were seeking more AMS guidance than is currently available to them. The most important aspects and targets for improvement of AMS guidance were: (i) quality of guidelines; (ii) availability of infectious diseases specialists; and (iii) suitability of AMS guidance to department context. Conclusions: Achieving prudent antibiotic use not only depends on individual and collective levels of commitment to follow AMS guidance but also on the quality, availability and suitability of the guidance itself. More substantial commitment from stakeholders is needed to allocate the required resources for delivering high-quality, available and relevant AMS guidance to make sure that the prescribers' AMS needs are met.

Mortality and Hospitalization Risks in Patients With Cancer and the SARS-CoV-2 Omicron Variant.

This cohort study compares the mortality and hospitalization risks among patients with vs without solid cancer and diagnosed with COVID-19 during the period when the Omicron variant was dominant.

A Profound Vitamin B12 Deficiency in a Patient with Lofgren's Syndrome.

Lofgren's syndrome is a unique manifestation of sarcoidosis presenting with erythema nodosum, bilateral hilar lymphadenopathy and migratory polyarthritis. A concurrent vitamin B12 deficiency is not well described and may be related to a rare gastrointestinal manifestation of sarcoid and Lofgren's syndrome. We describe a case of a 57-year-old male presented with migratory polyarthritis, erythemic nodules, edema of his legs and fever. His laboratory tests showed anemia with a profound vitamin B12 deficiency. Imaging demonstrated bilateral hilar adenopathy. Pathology revealed non-necrotizing granulomas consistent with sarcoidosis. The patient was started on prednisone and vitamin B12 supplements with improvement of his complaints and vitamin B12 levels. Sarcoidosis can manifest in many extrapulmonary organs, including the gastrointestinal tract, resulting in nutritional deficiencies, such as vitamin B12 deficiency. Treatment of these nutritional deficiencies includes treatment with steroids, as well as vitamin supplementation. We suggest this case to be a rare manifestation of gastrointestinal involvement in Lofgren syndrome; however, a biopsy from the GI tract was not performed to confirm the diagnosis. An informed consent was obtained from the patient. An institutional approval was not required for the publication of this case.

Clinical Outcomes of Hospitalized Patients with SARS-CoV-2 Omicron Variant vs. Influenza A During Influenza Season 2021 to 2022: A Retrospective Observational Study.

BACKGROUND: Influenza and coronavirus disease 2019 (COVID-19) are respiratory diseases with similar modes of transmission. In December 2021, influenza re-emerged after it had been undetected since March 2020 and the Omicron variant replaced the Delta variant. Data directly comparing the two diseases are scarce. OBJECTIVES: To compare the outcomes of patients with both the Omicron variant and influenza during 2021-2022. METHODS: We performed a retrospective study conducted in Beilinson hospital, Israel, from December 2021 to January 2022. We included all hospitalized patients with either laboratory-confirmed COVID-19 or influenza. The primary outcome was 30-day mortality. RESULTS: We identified 167 patients diagnosed with Omicron and 221 diagnosed with Influenza A. The median age was 71 years for Omicron and 65 years for influenza. Patients with Omicron had a significantly higher Charlson Comorbidity Index score (4 vs. 3, P < 0.001). Patients with Omicron developed more respiratory failure that needed mechanical ventilation (7% vs. 2%, P = 0.05) and vasopressors (14% vs. 2%, P < 0.001) than patients with influenza. In a multivariate model, 30-day mortality was lower in patients diagnosed with influenza than in patients diagnosed with Omicron (19/221 [9%] vs. 44/167 [26%], hazard ratio 0.45, 95% confidence interval 0.25-0.81). CONCLUSIONS: Patients diagnosed with Omicron had higher mortality than patients diagnosed with seasonal influenza. This finding could be due to differences in co-morbidities, the virus pathogenicity, and host responses to infection.

Outcomes of vaccinated versus unvaccinated COVID-19 patients in Israel during the Omicron and Delta waves—A retrospective cohort study / Resultados de pacientes con COVID-19 vacunados vs. no vacunados en Israel durante las olas de ómicron y delta: Un estudio de cohorte retrospectivo

Introduction Initiation of global vaccination significantly reduced the morbidity and mortality of COVID-19. During the Omicron wave, approximately 70% of the Israeli adult population was fully vaccinated, but the efficacy of the vaccine was questioned. Methods We conducted a retrospective cohort study of all adult patients admitted to the COVID-19 departments in Rabin Medical Center, during the Delta wave and the Omicron wave. Patients were matched in the 2 waves using the inverse probability of treatment weighting (IPTW) method and risk for mechanical ventilation and 30-day all-cause mortality was assessed. Results Vaccination had a significant effect on 30-day mortality in the Delta and Omicron waves with adjusted OR of 0.35 (0.17–0.70) and 0.5 (0.27–0.95) respectively. Nonetheless, the rate of mechanical ventilation was similar between the groups with OR of 0.75 (0.52–1.09) and 0.64 (0.40–1.01). Vaccination status did not change the length of admission in both waves. Conclusion We observed a decreased risk for 30-day mortality among vaccinated patients during the Delta and Omicron waves in Israel. This association, even though consistent, was of a lesser magnitude during the Omicron wave (AU)

Introducción La iniciación de la vacunación global redujo significativamente la morbilidad y la mortalidad de la COVID-19. Durante la ola de ómicron, aproximadamente 70% de la población adulta israelí estaba completamente vacunada, pero se cuestionó la eficacia de la vacuna. Métodos Realizamos un estudio de cohorte retrospectivo de todos los pacientes adultos ingresados en los departamentos de COVID-19 en el Centro Médico Rabin, durante las olas de delta y ómicron. Los pacientes fueron emparejados en las dos olas utilizando el método de ponderación inversa de probabilidad de tratamiento (IPTW) y se evaluó el riesgo de ventilación mecánica y la mortalidad por todas las causas a los 30 días. Resultados La vacunación tuvo un efecto significativo en la mortalidad a los 30 días en las olas de delta y ómicron con odds ratio (OR) ajustadas de 0,35 (0,17-0,70) y 0,5 (0,27-0,95), respectivamente. Sin embargo, la tasa de ventilación mecánica fue similar entre los grupos con OR de 0,75 (0,52-1,09) y 0,64 (0,40-1,01). El estado de vacunación no cambió la duración del ingreso en ambas olas.Conclusión Observamos un menor riesgo de mortalidad a los 30 días entre los pacientes vacunados durante las olas de delta y ómicron en Israel. Esta asociación, aunque constante, fue de menor magnitud durante la ola de ómicron (AU)

Outcomes of vaccinated versus unvaccinated COVID-19 patients in Israel during the Omicron and Delta waves-A retrospective cohort study.

INTRODUCTION: Initiation of global vaccination significantly reduced the morbidity and mortality of COVID-19. During the Omicron wave, approximately 70% of the Israeli adult population was fully vaccinated, but the efficacy of the vaccine was questioned. METHODS: We conducted a retrospective cohort study of all adult patients admitted to the COVID-19 departments in Rabin Medical Center, during the Delta wave and the Omicron wave. Patients were matched in the 2 waves using the inverse probability of treatment weighting (IPTW) method and risk for mechanical ventilation and 30-day all-cause mortality was assessed. RESULTS: Vaccination had a significant effect on 30-day mortality in the Delta and Omicron waves with adjusted OR of 0.35 (0.17-0.70) and 0.5 (0.27-0.95) respectively. Nonetheless, the rate of mechanical ventilation was similar between the groups with OR of 0.75 (0.52-1.09) and 0.64 (0.40-1.01). Vaccination status did not change the length of admission in both waves. CONCLUSION: We observed a decreased risk for 30-day mortality among vaccinated patients during the Delta and Omicron waves in Israel. This association, even though consistent, was of a lesser magnitude during the Omicron wave.

Clinical outcomes for Clostridioides difficile associated diarrhea in inflammatory bowel disease patients versus non-IBD population: A retrospective cohort study.

Patients with inflammatory bowel disease (IBD) have a higher incidence of Clostridioides difficile infection (CDI). Previous studies have demonstrated negative clinical outcomes in IBD patients with CDI compared to patients without CDI. The clinical presentation of CDI is indistinguishable from IBD exacerbation, thus posing a frequent clinical dilemma on the role of Clostridioides infection in the testing, diagnosis, and treatment of these patients. To compare clinical outcomes of CDI in patients with IBD to those without IBD. Retrospective cohort of adult patients admitted to Rabin Medical Center Israel between the years 2014 and 2020 with a concurrent diagnosis of IBD and CDI. Matching 1:2 was performed between the IBD patients and the non-IBD population with respect to age and sex. Sixty-seven patients with IBD and 134 patients without IBD were included in the study. The groups' median age was 40.6 (interquartile range [IQR] of 29.8-68.9), with 45.8% male and 54.2% female. The non-IBD group had a higher Charlson score with 2 (IQR 0; 5) versus 0 (IQR 0; 4) in the IBD group (P value <.01). Patients with IBD had more exposure to systemic antibiotics, 71.1% versus 26.3% (P value <.01). In a multivariable analysis we found no difference in 90-day mortality and rate of relapse between the 2 study groups with an odds ratio of 1.709 (95% confidence interval 0.321-9.905) and odds ratio of 0.209 (95% confidence interval 0.055-1.513) respectively. In our cohort patients with IBD who present with diarrhea and concomitant CDI have similar rates of relapse and mortality compared with patients without IBD.

Effectiveness of BNT162b2 Vaccination During Pregnancy in Preventing Hospitalization for Severe Acute Respiratory Syndrome Coronavirus 2 in Infants.

OBJECTIVE: To assess the clinical effectiveness of the BNT162b2 vaccine during pregnancy in preventing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) hospitalizations of infants. STUDY DESIGN: A retrospective, multicenter, 1:3 case-control (test-negative) study. Symptomatic hospitalized infants less than 6 months of age, with a positive SARS-CoV-2 polymerase chain reaction test between January 3, 2021, and March 11, 2021, were matched by age and time to negative controls, hospitalized with symptoms compatible with SARS-CoV-2 infection. Mothers were defined as fully vaccinated who received 2 doses of BNT162b2 with the second given 2 weeks to 6 months before delivery; or partially vaccinated, if they received only 1 dose or 2 doses with the second given more than 6 months or less than 2 weeks before delivery. Severe SARS-CoV-2 was defined as a need for assisted ventilation. RESULTS: We matched 116 SARS-CoV-2 positive infants with 348 negative controls with symptoms compatible with SARS-CoV-2 infection. The effectiveness of fully vaccinated mothers was 61.6% (95% CI, 31.9-78.4) and the effectiveness of partially vaccinated mothers was not significant. Effectiveness was higher in infants 0-2 vs 3-6 months of age. The effectiveness (57.1%; 95% CI, 22.8-76.4) was similar when excluding mothers who were infected with SARS-CoV-2 during pregnancy. The OR of severe infection in infants born to unvaccinated vs fully vaccinated mothers was 5.8. CONCLUSIONS: At least 2 doses of BNT162b2 vaccine administered during the second or third trimester of pregnancy had an effectiveness of 61.6% in decreasing hospitalization for SARS-CoV-2 infection in infants less than 6 months of age.

External Validity of a Randomized Controlled Trial on Duration of Antibiotics for the Treatment of Gram-Negative Bacteremia.

INTRODUCTION: Reports regarding the external validity of randomized controlled trials (RCTs) are scarce. We aimed to assess the population external validity of an investigator-initiated RCT on the duration of antibiotics for the treatment of Gram-negative bacteremia by comparing patients included in the RCT to patients that were not included in the trial. METHODS: Hospitalized patients with Gram-negative bacteremia were recruited into an RCT and randomized to receive 7 or 14 days of covering antibiotic therapy in Israel and Italy from 2013 to 2017. In a concomitant observational study, RCT participants were compared with patients who fulfilled the inclusion criteria but were not included in the trial due to participation in other trials, discharge before approached by researchers, refusal to participate, or unwillingness of the treating physician to allow participants' recruitment. RESULTS: Six hundred and four RCT patients were compared with 613 nonincluded patients. Almost 50% of nonincluded patients (288/613) were dependent on others for activities of daily living at baseline compared to 37.7% of RCT participants (228/604). Dementia was nearly 2-fold more frequent in nonincluded patients than those included (5.9% [36/613] versus 3.6% [22/604], p = 0.07). Patients who were not included in the RCT were more likely to acquire their infection in the hospital (53.3% [327/613] versus 29.1% [176/604], p < 0.001). The primary composite outcome of mortality, clinical failure, readmissions, or extended hospitalization at 90 days occurred in 353 of 613 nonincluded patients (57.6%) compared to 299 of 604 RCT participants (49.6%), p = 0.005. However, on multivariate analysis noninclusion in the RCT was not an independent risk factor for clinical failure and mortality. CONCLUSIONS: RCTs, even with broad eligibility criteria, do not represent the whole spectrum of patients and leave out a population with more severe illness for whom the evidence is lacking.

Re-Admission of COVID-19 Patients Hospitalized with Omicron Variant-A Retrospective Cohort Study.

In accordance with previous publications, re-admission rates following hospitalization of patients with COVID-19 is 10%. The aim of the current study was to describe the rates and risk factors of hospital re-admissions two months following discharge from hospitalization during the fifth wave due to the dominant Omicron variant. A retrospective cohort study was performed in Rabin Medical Center, Israel, from November 2021 to February 2022. The primary outcome was re-admissions with any diagnosis; the secondary outcome was mortality within two months of discharge. Overall, 660 patients were hospitalized with a diagnosis of COVID-19. Of the 528 patients discharged from a primary hospitalization, 150 (28%) were re-admitted. A total of 164 patients (25%) died throughout the follow-up period. A multi-variable analysis determined that elevated creatinine was associated with a higher risk of re-admissions. Rates of re-admissions after discharge during the Omicron wave were considerably higher compared to previous waves. A discharge plan for surveillance and treatment following hospitalization is of great importance in the management of pandemics.

A Biphasic COVID-19 Clinical Course in Anti-CD20 Treated Patients: Case Series and Review of the Literature.

We describe four cases of COVID-19 infection during the Omicron wave, in patients treated with anti-CD20 monoclonal antibodies. All cases follow a similar biphasic clinical course consisting of respiratory deterioration, which occurred a few weeks after convalescence from initial mild to asymptomatic infection. Possible explanations are discussed. LEARNING POINTS: Four cases of COVID-19 infection in anti-CD20 treated patients are described.These cases display a unique biphasic course that was previously undescribed: respiratory deterioration weeks after convalescence.Awareness of such a course and rapid utilisation of bronchoalveolar lavage will lead to quicker diagnosis and more timely, appropriate treatment.

Three-month follow-up of durability of response to the third dose of the SARS-CoV-2 BNT162b2 vaccine in adults aged 60 years and older: a prospective cohort study.

OBJECTIVE: To evaluate the durability of response 3 months after the third BNT162b2 vaccine in adults aged 60 years and older. DESIGN: Prospective cohort study. SETTING: Single tertiary centre. PARTICIPANTS: Healthcare workers/family members aged ≥60 years old who received the third BNT162b2 dose. INTERVENTIONS: Blood samples were drawn immediately before (T0), 10-19 days (T1) and 74-103 days (T2) after the third dose. PRIMARY AND SECONDARY OUTCOME MEASURES: Anti-spike IgG titres were determined using a commercial assay and seropositivity was defined as ≥50 arbitrary units (AU)/mL. Neutralising antibody titres were determined at T2. Adverse events, COVID-19 infections and Clinical Frailty Scale (CFS) levels were documented. RESULTS: The analysis included 97 participants (median age, 70 years (IQR, 66-74), 58% CFS level 2). IgG titres, which increased significantly from T0 to T1 (median, 440 AU/mL (IQR, 294-923) and median, 25 429 AU/mL (IQR, 14 203-36 114), respectively; p<0.001), decreased significantly by T2, but all remained seropositive (median, 8306 AU/mL (IQR, 4595-14 701), p<0.001 vs T1). In a multivariable analysis, only time from the second vaccine was significantly associated with lower IgG levels at T2 (p=0.017). At T2, 60 patients were evaluated for neutralising antibodies; all were seropositive (median, 1294 antibody titres; IQR, 848-2072). Neutralising antibody and anti-spike IgG levels were correlated (r=0.6, p<0.001). No major adverse events or COVID-19 infections were reported. CONCLUSIONS: Anti-spike IgG and neutralising antibody levels remain adequate 3 months after the third BNT162b2 vaccine in healthy adults aged ≥60 years, although the decline in IgG is concerning. A third dose of vaccine in this population should be top priority.

A Transient Inflammatory Reaction with a B-Cell Lymphoid Infiltrate and Dysplastic Bone Marrow Changes Associated with the BNT162b2 COVID-19 Vaccine.

COVID-19 vaccines were introduced soon after the COVID-19 pandemic emerged in 2020. Various side effects were reported worldwide, including several types of common systemic side effects such as fever and general fatigue. Reports of other rare manifestations also emerged. We report the case of an adult male with a rare systemic syndrome mimicking lymphoma after he had received the first dose of an mRNA-based COVID-19 vaccine. After nearly 6 months of investigation with suspicion for an infection or malignancy, all symptoms resolved, laboratory tests normalized, and imaging showed no sign of active disease. LEARNING POINTS: A lymphoma-like reaction is a possible side effect of COVID-19 vaccination.It is important to rule out other causes of systemic symptoms before diagnosing a reaction to a COVID-19 vaccine.A lymphoma-like reaction following administration of a COVID-19 vaccine has a good prognosis.

Predicting In-Hospital Antibiotic Use in the Medical Department: Derivation and Validation Study.

BACKGROUND: The rise of multi-drug-resistant pathogens and nosocomial infections among hospitalized patients is partially attributed to the increased use of antibiotic therapy. A prediction model for in-hospital antibiotic treatment could be valuable to target preventive strategies. METHODS: This was a retrospective cohort study, including patients admitted in 2018 to medical departments and not treated with antibiotics during the first 48 h. Data available at hospital admission were used to develop a logistic model to predict the probability of antibiotic treatment during hospitalization. The performance of the model was evaluated in two independent validation cohorts. RESULTS: In the derivation cohort, antibiotic treatment was initiated in 454 (8.1%) out of 5592 included patients. Male gender, lower functional capacity, prophylactic antibiotic treatment, medical history of atrial fibrillation, peripheral vascular disease, solid organ transplantation, chronic use of a central venous catheter, urinary catheter and nasogastric tube, albumin level, mental status and vital signs at presentation were identified as predictors for antibiotic use during hospitalization and were included in the prediction model. The area under the ROC curve (AUROC) was 0.72 (95% CI 0.70-0.75). In the highest probability group, the percentage of antibiotic treatment was 18.2% (238/1,307). In the validation cohorts, the AUROC was 0.73 (95% CI 0.68-0.77) and 0.75 (95% CI 0.72-0.78). In the highest probability group, the percentage of antibiotic treatment was 12.5% (66/526) and 20.7% (244/1179) of patients. CONCLUSIONS: Our prediction model performed well in the validation cohorts and was able to identify a subgroup of patients at high risk for antibiotic treatment.

Humoral and T-Cell Response before and after a Fourth BNT162b2 Vaccine Dose in Adults ≥60 Years.

Both humoral and cellular anamnestic responses are significant for protective immunity against SARS-CoV-2. In the current study, the responses in elderly people before and after a fourth vaccine dose of BNT162b2 were compared to those of individuals immunized with three vaccine doses. Although a boost effect was observed, the high response following the third administration questions the necessity of an early fourth boost.

Improved immunogenicity following the third dose of BNT162b2 mRNA vaccine in heart transplant recipients.

OBJECTIVES: The immunogenicity of two-dose severe acute respiratory syndrome coronavirus 2 vaccine is lower among heart transplant (HTx) recipients, compared with the general population. Our aim was to assess the immunogenicity of a third-dose vaccine in HTx recipients. METHODS: This is a prospective cohort study of HTx recipients who received a third dose of the BNT162b2 vaccine. Immunogenicity was assessed by serum levels of anti-spike immunoglobulin G (S-IgG), taken at baseline and 14-28 days after the third dose. Titres above 50 U/ml were interpreted positive. RESULTS: We Included 42 HTx recipients at a median age of 65 years [interquartile range (IQR) 58-70]. At baseline, the median of 27 days (IQR 13-42) before the third dose and the median titre of the whole group was 18 U/ml (IQR 4-130). Only 14 patients (33%) were S-IgG seropositive. After the third dose, the proportion of seropositive patients increased significantly to 57% (P = 0.05) and the median titre increased significantly to 633 U/ml (IQR 7-6104, P < 0.0001). Younger age at HTx (OR per 1-year decrease 1.07, P = 0.05), low tacrolimus serum level (OR per 1-unit decrease 2.28, P = 0.02), mammalian target of rapamycin use (OR 13.3, P = 0.003), lack of oral steroids use (OR 4.17, P = 0.04) and lack of calcineurin inhibitor use (71% of responders vs 100% non-responders received calcineurin inhibitors, P = 0.01) were predictors of seropositive result after the third dose. However, no significant association was detected following adjustment for baseline S-IgG titre. CONCLUSIONS: Third-dose booster of BNT162b2 vaccine significantly increased immunogenicity among HTx recipients who previously received a two-dose vaccine.

Comparing Coronavirus Disease 2019 (COVID-19) Pandemic Waves in Hospitalized Patients: A Retrospective, Multicenter, Cohort Study.

BACKGROUND: Coronavirus disease 2019 was first diagnosed in Israel at the end of February 2020. By the end of June 2021, there were 842 536 confirmed cases and 6428 deaths. Our aim in this multicenter, retrospective, cohort study is to describe the demographic and clinical characteristics of hospitalized patients and compare the pandemic waves before immunization. METHODS: Of 22 302 patients hospitalized in general medical centers, we randomly selected 6329 for the study. Of these, 3582 and 1106 were eligible for the study in the first period (first and second waves) and in the second period (third wave), respectively. RESULTS: Thirty-day mortality was higher in the second period than in the first period, 25.20% vs 13.68% (P < .001). Invasive mechanical ventilation supported 9.19% and 14.21% of patients in the first period and second period, respectively. Extracorporeal membrane oxygenation (ECMO) was used more than twice as often in the second period. CONCLUSIONS: Invasive ventilation, use of ECMO, and mortality rate were 1.5 to 2 times higher in the second period than in the first period. In the second period, patients had a more severe presentation and higher mortality than those in the first period.

Six-months immunogenicity of BNT162b2 mRNA vaccine in heart transplanted and ventricle assist device-supported patients.

AIMS: To assess the 6 months immunogenicity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccine in a population of heart transplanted (HTx) recipients and left ventricular assist device (LVAD)-supported patients. METHODS AND RESULTS: A prospective single-centre cohort study of HTx recipients and LVAD-supported patients who received a two-dose SARSCoV-2 mRNA vaccine (BNT162b2, Pfizer-BioNTech). Whole blood for anti-spike IgG (S-IgG) antibodies were drawn at 6 months after the first vaccine dose. S-IgG data at 6 weeks were available for a subgroup of HTx recipients. S-IgG ≥ 50 AU/mL were interpreted positive. The cohort included 53 HTx recipients and 18 LVAD-supported patients. The median time from HTx or LVAD implantation to the 1st vaccine dose was 90 (IQR 30, 172) months and 22 (IQR 6, 78) months, respectively. The seropositivity rates of S-IgG antibodies and their titre levels in HTx recipients and LVAD-supported patients were 45% and 83% respectively, (P = 0.006), and 35 (IQR 7, 306) AU/mL and 311 (IQR 86, 774) AU/mL, respectively, (P = 0.006). Reduced SARSCoV-2 vaccine immunogenicity in HTx recipients was associated with older age [odds ratio (OR) 0.917 confidence interval (CI 0.871, 0.966), P = 0.011] and with the use of anti-metabolites-based immunosuppressive regimens [OR 0.224 (CI 0.065, 0.777), P = 0.018]. mTOR inhibitors were associated with higher immunogenicity [OR 3.1 (CI 1.01, 9.65), P = 0.048]. Out of 13 HTx recipients who were S-IgG seropositive at 6 weeks after the first vaccine dose, 85% remained S-IgG seropositive at 6 month follow-up. CONCLUSIONS: At 6 months post-vaccination, S-IgG immunogenicity in HTx recipients is low, particularly in older HTx recipients and in those treated with anti-metabolites drugs.