This is a multicenter prospective observational study that included a large cohort ( n = 397) of allogeneic (allo‐HSCT; ( n = 311) and autologous (ASCT) hematopoietic stem cell transplant ( n = 86) recipients who were monitored for antibody detection within 3–6 weeks after complete severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) vaccination from February 1, 2021, to July 20, 2021. Most patients ( n = 387, 97.4%) received mRNA‐based vaccines. Most of the recipients (93%) were vaccinated more than 1 year after transplant. Detectable SARS‐CoV‐2‐reactive antibodies were observed in 242 (78%) of allo‐HSCT and in 73 (85%) of ASCT recipients. Multivariate analysis in allo‐HSCT recipients identified lymphopenia < 1 × 10 9 /ml (odds ratio [OR] 0.33, 95% confidence interval [95% CI] 0.16–0.69, p = .003), active graft versus host disease (GvHD; OR 0.51, 95% CI 0.27–0.98, p = .04) and vaccination within the first year of transplant (OR 0.3, 95% CI 0.15–0.9, p = .04) associated with lower antibody detection whereas. In ASCT, non‐Hodgkin's lymphoma (NHL; OR 0.09, 95% CI 0.02–0.44, p = .003) and active corticosteroid therapy (OR 0.2, 95% CI 0.02–0.87, p = .03) were associated with lower detection rate. We report an encouraging rate of SARS‐CoV‐2‐reactive antibodies detection in these severe immunocompromised patients. Lymphopenia, GvHD, the timing of vaccine, and NHL and corticosteroids therapy should be considered in allo‐HSCT and ASCT, respectively, to identify candidates for SARS‐CoV‐2 antibodies monitoring.

Monitoring Torque teno virus (TTV) DNA load helps to estimate the risk of opportunistic infections in solid organ transplant recipients. We investigated whether the early kinetic pattern of plasma TTV DNA load after allogeneic hematopoietic stem cell transplantation (allo-HSCT) associates with subsequent CMV and EBV DNAemia. This study included 71 allo-HSCT patients. We found that the area under the curve (AUC) for log TTV DNA loads quantified by days 20 and 30 after transplantation (TTV DNA load AUC), was significantly lower (P=0.036) in patients who subsequently developed CMV DNAemia requiring preemptive antiviral therapy (n=17) than in those who did not (n=8) or had no CMV DNAemia (n=19). Patients displaying TTV DNA load AUC⩽2.8 copies × days × mL were more likely to have high-level CMV DNAemia. A trend towards a direct correlation between TTV DNA AUC and CMV-specific interferon-γ CD8+ T-cell counts by day +30 was noted (P=0.095). However, this dynamic parameter was not useful for anticipating the occurrence of either CMV recurrences (n=12) or EBV DNAemia (n=34). In summary, it may be possible to identify a subset of allo-HSCT patients at a high risk of developing high-level CMV DNAemia by analyzing the kinetics of plasma TTV DNA load early after engraftment.

This study shows that influenza vaccination may have a clinical benefit in allo-HSCT recipients with virologicallly confirmed RVI, in terms of lower influenza RVI prevalence, LRTD progression and hospital admission.

Epidemiologic data about coronaviruses (CoVs) and human bocavirus (HBoV) in the setting of allogeneic hematopoietic stem cell transplantation (allo-HSCT) are scarce. We conducted a prospective longitudinal study on respiratory viral infections (RVIs) in allo-HSCT recipients with respiratory symptoms from December 2013 until June 2016. Respiratory virus in upper and/or lower respiratory tract (URT and LRT) specimens were tested using Luminex xTAG RVP Fast v1 assay. Seventy-nine consecutive allo-HSCT recipients developed a total of 192 virologically documented RVI episodes over 30 months. The median follow-up after RVI was 388 days (range, 5 to 923). CoV or HBoV was detected in 27 of 192 episodes (14%); 18 of 79 recipients (23%) developed a total of 21 CoV RVI episodes, whereas 6 recipients (8%) had 1 HBoV RVI episode each. Fourteen CoV RVI episodes were limited to the URT, whereas 7 affected the LRT. Co-pathogens were detected in 8 (38%) CoV cases. Type OC43 CoV was the dominant type (48%) followed by NL63 (24%), KHU1 (19%), and 229E (9%); the CoV hospitalization rate was 19%, whereas mortality was 5% (1 patient without any other microbiologic documentation). Among the 6 recipients with HBoV (3%), only 1 had LRT involvement and no one died from respiratory failure. In 5 cases (83%) HBoV was detected along with other viral co-pathogens. CoV RVIs are common after allo-HSCT, and in a significant proportion of cases CoV progressed to LRT and showed moderate to severe clinical features. In contrast, HBoV RVIs were rare and mostly presented in the context of co-infections.

No abstract