[Vaccination of children and adolescents treated for acute leukemia, excluding HSCT recipients: Recommendations of the French Society for Childhood and Adolescent Cancer and Leukemia (SFCE)]

Children and adolescents who are being treated or have been treated for acute leukemia have a secondary immunodeficiency linked to chemotherapy, resulting in an increased risk of infections. Some of which can be prevented by vaccination but its effectiveness is not optimal during chemotherapy. Upon cessation of chemotherapy, the time required for immune reconstitution varies from three months to more than a year, depending on lymphocyte subpopulations, the patient's age, and the intensity of the treatment received. Although they may have regained their immune functions, studies show that most patients have lost part of their vaccine-induced protection post-chemotherapy and require booster doses of vaccines. Most practitioners agree on the importance of vaccinating or revaccinating these children, but practices are heterogeneous among pediatric hematologist-oncologists in France. Based on a practice study and a recent review of the literature, this work aims to propose new French recommendations for the vaccination strategy to be adopted for children and adolescents treated or recently treated for acute leukemia, excluding allogeneic transplant recipients, in 2024. These recommendations specifically include the vaccination protocols for human papillomavirus and meningococcal infections but do not address the COVID-19 vaccination, as its guidelines are subject to rapid changes.

Humoral response to SARS-CoV-2 and seasonal coronaviruses in COVID-19 patients

We used enzyme-linked immunoassay methods to measure the prevalence and the levels of antibody responses to the nucleocapsid (N) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and four seasonal human coronaviruses (HCoV-OC43, HCoV-HKU1, HCoV 229E, and HCoV-NL63) in a cohort of 115 convalescent plasma donors infected with SARS-CoV-2 (1-61 days after symptom onset) compared to antibody levels in 114 individuals with no evidence of a recent infection with SARS-CoV-2. In the humoral response to the four seasonal coronaviruses, only HCoV-HKU1- and HCoV-229E-assays showed slightly elevated antibody levels in the COVID group compared to the control group. While in the COVID-group the levels of SARS-CoV-2 antibodies correlated significantly with disease severity, no association was found in the levels of antibodies against the seasonal coronaviruses. The most striking result in both groups was that the levels of antibodies against all tested coronaviruses, including the new SARS-CoV-2 showed a highly significant correlation with each other. There seems to be an individual predisposition to a weaker or stronger humoral immune response against all known seasonal human coronaviruses including the new SARS-CoV-2, which could lead to a definition of low and high responders against human coronaviruses with potential impact on the assessment of postinfection antibody levels and protection.

Clinical Features and Outcomes of Immunocompromised Children Hospitalized With Laboratory-Confirmed Influenza in the United States, 2011-2015

BACKGROUND

Existing data on the clinical features and outcomes of immunocompromised children with influenza are limited.

METHODS

Data from the 2011-2012 through 2014-2015 influenza seasons were collected as part of the Centers for Disease Control and Prevention (CDC) Influenza Hospitalization Surveillance Network (FluSurv-NET). We compared clinical features and outcomes between immunocompromised and nonimmunocompromised children (<18 years old) hospitalized with laboratory-confirmed community-acquired influenza. Immunocompromised children were defined as those for whom ≥1 of the following applies: human immunodeficiency virus/acquired immunodeficiency syndrome, cancer, stem cell or solid organ transplantation, nonsteroidal immunosuppressive therapy, immunoglobulin deficiency, complement deficiency, asplenia, and/or another rare condition. The primary outcomes were intensive care admission, duration of hospitalization, and in-hospital death.

RESULTS

Among 5262 hospitalized children, 242 (4.6%) were immunocompromised; receipt of nonsteroidal immunosuppressive therapy (60%), cancer (39%), and solid organ transplantation (14%) were most common. Immunocompromised children were older than the nonimmunocompromised children (median, 8.8 vs 2.8 years, respectively; P < .001), more likely to have another comorbidity (58% vs 49%, respectively; P = .007), and more likely to have received an influenza vaccination (58% vs 39%, respectively; P < .001) and early antiviral treatment (35% vs 27%, respectively; P = .013). In multivariable analyses, immunocompromised children were less likely to receive intensive care (adjusted odds ratio [95% confidence interval], 0.31 [0.20-0.49]) and had a slightly longer duration of hospitalization (adjusted hazard ratio of hospital discharge [95% confidence interval], 0.89 [0.80-0.99]). Death was uncommon in both groups.

CONCLUSIONS

Immunocompromised children hospitalized with influenza received intensive care less frequently but had a longer hospitalization duration than nonimmunocompromised children. Vaccination and early antiviral use could be improved substantially. Data are needed to determine whether immunocompromised children are more commonly admitted with milder influenza severity than are nonimmunocompromised children.

A comparison of viral microneutralization and haemagglutination inhibition assays as measures of seasonal inactivated influenza vaccine immunogenicity in the first year after reduced intensity conditioning, lymphocyte depleted allogeneic haematopoietic stem cell transplant

Traditionally, immune response to influenza vaccines has been measured using the haemagglutination inhibition (HAI) assay. A broader repertoire of techniques including the sensitive viral microneutralization (VMN) assay is now recommended by the European Medicines Agency (EMA). Comparing HAI and VMN, we determined immune response to a trivalent 2015-2016 seasonal inactivated influenza vaccine (SIIV) administered to 28 recipients of allogeneic haematopoietic stem cell transplant (HSCT). Vaccination was within the first-year post-transplant at a median of 78.5 (24-363) days. The proportion of patients with baseline and post-vaccination HAI titres ≥ 1:40 were 28.6% and 25% for A(H1N1)pdm09, 14.3% at both timepoints for A(H3N2), and 32.1% and 25% for B(Phuket). Pre and Post-vaccination geometric mean titres(GMT) were higher by VMN than HAI for A(H1N1)pdm09 and A(H3N2), but lower for B(Phuket)(p=<0.05). Geometric mean ratios(GMR) of baseline and post-vaccination titres were similar by HAI and VMN(p > 0.05) for all components. A single seroconversion to A(H1N1) was detected by ELISA-VMN. None of patient age, lymphocyte count, days from transplant to vaccination, donor type, or graft-versus-host disease (GVHD) or immunosuppressive therapy (IST) at vaccination correlated with baseline or post-vaccination titres by either assay. This absence of seroresponse to SIIV in the first-year post HSCT highlights the need for novel immunogenic vaccination formulations and schedules in this high-risk population.

A Quality Improvement Initiative to Increase and Sustain Influenza Vaccination Rates in Pediatric Oncology and Stem Cell Transplant Patients

Introduction:

Influenza vaccination of pediatric oncology and stem cell transplant (SCT) patients is crucial due to high risk of complications. Achieving high vaccination rates to prevent illness is often limited by competing demands and intensive treatment. A quality improvement (QI) initiative beginning influenza season 2012–2013 aimed to achieve and sustain high vaccination rates in active patients > 6 months of age, receiving cancer therapy or SCT within 6 months before or at any time during the season, and > 100 days after allogeneic SCT.

Methods:

We identified key drivers and barriers to success from an initially developed vaccination process that proved to be burdensome. Change ideas were implemented through multiple tests of change during the QI initiative. Iterations within and across 4 subsequent seasons included patient identification through chemotherapy orders, provider education, incorporating vaccination into routine work-flow, continuous data analysis and feedback, and use of new reporting technology.

Results:

Initial vaccination rates were < 70%, increasing to 89% after the QI initiative began and subsequently sustained between 85% and 90%. Active patients were significantly more likely to be vaccinated during the initiative (odds ratio, 3.7; 95% CI, 2.9–4.6) as compared with the first 2 seasons.

Conclusions:

High influenza vaccination rates can be achieved and maintained in a pediatric oncology/SCT population using strategies that correctly identify patients at highest risk and minimize process burden.

Clinical Profile and Outcome of Influenza A/H1N1 in Pediatric Oncology Patients During the 2015 Outbreak: A Single Center Experience from Northern India

BACKGROUND

Owing to their immunocompromised status, childhood cancer patients on chemotherapy are at a greater risk for Influenza infection and its associated complications. There is limited data available on the clinical profile and outcome of Influenza A/H1N1 in this subset of patients.

METHODS

A retrospective study was performed of Influenza A/H1N1 cases diagnosed between January 2015 to December 2015 in the in-patients of Pediatric Oncology unit of a tertiary care hospital from Northern India.

RESULTS

In total, 16 children were diagnosed with laboratory confirmed H1N1. Most frequent symptoms were fever and cough. Oseltamivir was administered to all patients. Complications encountered were delay/interruption of antineoplastic therapy (9), need for respiratory support (5), and air leaks (1). Prolonged viral shedding was encountered in 50% of patients who were retested for H1N1 in their throat swabs. There were 2 deaths, 1 in a child of Acute Lymphoblastic Leukemia on induction therapy and another in a child with anaplastic Wilms tumor.

CONCLUSIONS

Childhood cancer patients infected with Influenza A/H1N1 are at risk of serious illness and higher mortality. Delay of anticancer treatment is a concern in these infected children. Prompt initiation of antivirals and an optimum duration of treatment are warranted to reduce the morbidity and mortality.

Burden of Influenza-Related Hospitalizations and Attributable Mortality in Pediatric Acute Lymphoblastic Leukemia

BACKGROUND

Influenza can be severe in patients with underlying malignancy; however, the rate of influenza hospitalizations and attributable mortality in children with cancer is unknown.

METHODS

We performed a retrospective cohort study among 10 698 children with new-onset acute lymphoblastic leukemia (ALL) from 41 US children's hospitals between January 1999 and September 2011. Influenza-related hospitalizations were identified using ICD-9 discharge diagnosis codes, excluding hospitalizations during low-prevalence influenza periods. Follow-up was censored at the earliest of 5 events: end of study period, expected end of chemotherapy, last known hospitalization, hematopoietic stem cell transplant, or death. Data were collected on hospitalization characteristics and resource utilization. Hospitalization rates were calculated using season-adjusted person-time. Crude attributable in-hospital mortality was calculated using baseline mortality for noninfluenza hospitalizations during the same period. Subgroup analysis was performed by time from ALL diagnosis and by age category.

RESULTS

The rate of influenza-related hospitalizations was 618.3 per 100 000 person-months. Rates were similar by time from ALL diagnosis and across age categories. Overall attributable in-hospital mortality was 1.0% (95% confidence interval [CI], 0.3%-2.3%) and was highest for children <6 months from diagnosis (1.6%; 95% CI, 0.4%-4.5%) and children <2 years of age (6.7%; 95% CI, 1.3%-22.7%). Total length of stay, days of broad-spectrum antibiotic exposure, and duration of intensive care were significantly greater for influenza-related hospitalizations compared with noninfluenza hospitalizations.

CONCLUSIONS

The burden of influenza-related hospitalizations in children with ALL is high and associated with significantly increased resource utilization and attributable mortality.

Infections Caused by Acinetobacter baumannii in Recipients of Hematopoietic Stem Cell Transplantation

Acinetobacter baumannii (A. baumannii) is a Gram-negative, strictly aerobic, non-fermentative coccobacillus, which is widely distributed in nature. Recently, it has emerged as a major cause of health care-associated infections (HCAIs) in addition to its capacity to cause community-acquired infections. Risk factors for A. baumannii infections and bacteremia in recipients of hematopoietic stem cell transplantation include: severe underlying illness such as hematological malignancy, prolonged use of broad-spectrum antibiotics, invasive instrumentation such as central venous catheters or endotracheal intubation, colonization of respiratory, gastrointestinal, or urinary tracts in addition to severe immunosuppression caused by using corticosteroids for treating graft versus host disease. The organism causes a wide spectrum of clinical manifestations, but serious complications such as bacteremia, septic shock, ventilator-associated pneumonia, extensive soft tissue necrosis, and rapidly progressive systemic infections that ultimately lead to multi-organ failure and death are prone to occur in severely immunocompromised hosts. The organism is usually resistant to many antimicrobials including penicillins, cephalosporins, trimethoprim-sulfamethoxazole, almost all fluoroquinolones, and most of the aminoglycosides. The recently increasing resistance to carbapenems, colistin, and polymyxins is alarming. Additionally, there are geographic variations in the resistance patterns and several globally and regionally resistant strains have already been described. Successful management of A. baumannii infections depends upon appropriate utilization of antibiotics and strict application of preventive and infection control measures. In uncomplicated infections, the use of a single active beta-lactam may be justified, while definitive treatment of complicated infections in critically ill individuals may require drug combinations such as colistin and rifampicin or colistin and carbapenem. Mortality rates in patients having bacteremia or septic shock may reach 70%. Good prognosis is associated with presence of local infection, absence of multidrug resistant strain, and presence of uncomplicated infection while poor outcome is associated with severe underlying medical illness, bacteremia, septic shock, multi-organ failure, HCAIs, admission to intensive care facilities for higher levels of care, and culture of certain aggressive genotypes of A. baumannii.