Clinical features and outcome of 2009-influenza A (H1N1) after allogeneic hematopoietic SCT

How Comorbidities Affect Hospitalization from Influenza in the Pediatric Population

Influenza is a contagious respiratory illness and can lead to hospitalization and even death. Understanding how comorbidities affect the severity of influenza can help clinical management. The aim of this study is to offer more information about comorbidities that might be associated with the severity of influenza in children. We used a statewide network in Rhode Island, USA, to extract data for laboratory-confirmed influenza cases among children 19 years old or younger. We identified 1169 lab-confirmed influenza cases. The most common comorbidities were asthma (17.1%), neurodevelopmental disorders (10.3%), gastrointestinal disorders (7.6%), atopic dermatitis (7%), and endocrine and metabolic diseases (6.8%). Interestingly, 80.8% (63 out of 78) of children who had an influenza-related hospital admission had at least one comorbidity, and among hospitalized children with influenza, the most common comorbidities were neurological diseases (28.2%, 22/78), gastrointestinal disorders (25.6%, 20/78), endocrine and metabolic diseases (24.4%, 19/78), and neurodevelopmental disorders (23.1%, 18/78). Children with endocrine or metabolic diseases were 8.23 times more likely to be admitted to the hospital, and children with neurological disorders were 6.35 times more likely to be admitted (OR: 8.23, 95% CI: 4.42–15.32 and OR: 6.35, 95% CI: 3.60–11.24, respectively). In summary, we identified specific comorbidities associated with influenza hospitalization and length of hospital stay, and these groups should be prioritized for public health interventions.

Impact of Influenza Infection Among Adult and Pediatric Populations With Hematologic Malignancy and Hematopoietic Stem Cell Transplant: A Systematic Review and Meta-Analysis

PURPOSE

Influenza is increasingly recognized as a leading cause of morbidity and mortality in patients with hematologic malignancies and recipients of hematopoietic stem cell transplantation (HSCT). However, the impact of influenza on this population has not been previously evaluated in a systematic review. This study systematically reviewed and summarized the outcomes of influenza infection as to in-hospital influenza-related mortality, development of lower respiratory tract infection and acute respiratory distress syndrome, need for hospitalization, intensive care unit admission, and mechanical ventilation.

METHODS

We conducted a systematic search of literature using the PubMed and EMBASE databases for articles published from January 1989 through January 19, 2020, reporting laboratory-confirmed influenza in patients of any age with hematologic malignancies and HSCT. Time from transplantation was not included in the search criteria. The impact of antiviral therapy on influenza outcomes was not assessed due to heterogeneity in antiviral treatment provision across the studies. Patients with influenza-like illness, solid-tumor cancers, or nonmalignant hematologic diseases were excluded from the study. A random-effects meta-analysis was performed to estimate the prevalences and 95% CIs of each outcome of interest. A subgroup analysis was carried out to assess possible sources of heterogeneity and to evaluate the potential impact of age on the influenza infection outcomes. Heterogeneity was assessed using the I² statistic.

FINDINGS

Data from 52 studies providing data on 1787 patients were included in this analysis. During seasonal epidemics, influenza-related in-hospital mortality was 16.60% (95% CI, 7.49%-27.7%), with a significantly higher death rate in adults compared to pediatric patients (19.55% [95% CI, 10.59%-29.97%] vs 0.96% [95% CI, 0%-6.77%]; P < 0.001). Complications from influenza, such as lower respiratory tract infection, developed in 35.44% of patients with hematologic malignancies and HSCT recipients, with a statistically significant difference between adults and children (46.14% vs 19.92%; P < 0.001). However, infection resulted in a higher hospital admission rate in pediatric patients compared to adults (61.62% vs 22.48%; P < 0.001). For the 2009 H1N1 pandemic, no statistically significant differences were found between adult and pediatric patients when comparing the rates of influenza-related in-hospital mortality, lower respiratory tract infection, and hospital admission. Similarly, no significant differences were noted in any of the outcomes of interest when comparing H1N1 pandemic with seasonal epidemics.

IMPLICATIONS

Regardless of influenza season, patients, and especially adults, with underlying hematologic malignancies and HSCT recipients with influenza are at risk for severe outcomes including lower respiratory tract infection and in-hospital mortality.

Influenza Adherence Tool Kit: Implementation and Evaluation Among Allogeneic Hematopoietic Transplantation Recipients

BACKGROUND

Allogeneic transplantation is associated with significant complications, such as influenza, a common virus in the post-transplantation setting that can be detrimental to patients. Therefore, patients should adhere to influenza vaccinations.
.

OBJECTIVES

The objectives of this project were to improve influenza adherence rates from 2015-2016, to increase transplantation recipients' knowledge of the importance of vaccination, and to evaluate the barriers to and facilitators of adherence rates to influenza vaccinations.
.

METHODS

A pre-/postscreening survey was used, as well as a tool kit with an education pamphlet and financial incentive, and a reminder letter. 
.

FINDINGS

Forty-eight eligible patients participated in the study, and 32 completed the prescreening questionnaire. The adherence rate for the 2015-2016 influenza season improved compared to the baseline vaccination rate. The findings revealed a strong association between provider recommendation and vaccination adherence.

Successful use of oseltamivir prophylaxis in managing a nosocomial outbreak of influenza A in a hematology and allogeneic stem cell transplant unit

AIM

To describe a nosocomial outbreak of H1N1 influenza A in an inpatient hematology and allogeneic stem cell transplant unit and outcomes of universal oseltamivir prophylaxis.

METHODS

Medical records of all patients admitted to the unit were reviewed to define the nosocomial outbreak, commencing 1 week prior to the index case until 4 weeks following institution of oseltamivir prophylaxis. Timelines for clinical symptoms, viral spread, management, patient outcomes and follow up testing were constructed. All cases of influenza were confirmed on nasopharyngeal swabs and/or bronchoalveolar lavages collected for polymerase chain reaction testing.

RESULTS

In addition to the index case, further 11 patients were diagnosed with influenza A during the outbreak. Six patients (50%) had influenza-like-illness, five (42%) had respiratory symptoms only and one (8%) was asymptomatic. In total, five patients died, including four (33%) patients who were admitted to intensive care. A clustering of seven cases led to recognition of the outbreak and subsequent commencement of universal prophylaxis with oseltamivir 75 mg/day in all inpatients within the unit. Strict infection control processes were reinforced concurrently. There were no further cases of influenza A linked to the outbreak after the implementation of universal oseltamivir prophylaxis. Three later cases were linked to H1N1 exposure during the original outbreak.

CONCLUSION

H1N1 influenza infection is associated with significant mortality in hematology patients. Universal prophylaxis with oseltamivir during a nosocomial outbreak appeared to be effective in controlling spread of the virus. We recommend early institution of infection control and universal prophylaxis in any nosocomial outbreak of influenza.

BCSH/BSBMT/UK clinical virology network guideline: diagnosis and management of common respiratory viral infections in patients undergoing treatment for haematological malignancies or stem cell transplantation

A joint working group established by the Haemato-oncology subgroup of the British Committee for Standards in Haematology, the British Society for Bone Marrow Transplantation and the UK Clinical Virology Network has reviewed the available literature and made recommendations for the diagnosis and management of respiratory viral infections in patients with haematological malignancies or those undergoing haematopoietic stem cell transplantation. This guideline includes recommendations for the diagnosis, prevention and treatment of respiratory viral infections in adults and children. The suggestions and recommendations are primarily intended for physicians practising in the United Kingdom.

Influenza prevention and treatment in transplant recipients and immunocompromised hosts

The host immune response is critical for the control and clearance of influenza virus after initial infection. Unfortunately, key components of the innate and adaptive responses to influenza are compromised in solid organ and hematopoietic stem cell transplant recipients. As a result, influenza in these key patient populations is associated with prolonged viral shedding, more frequent complications, including bacterial and fungal superinfections and rejection, and increased mortality. While vaccine is the critical prophylaxis strategy in other populations, response rates are diminished, particularly early post-transplant, among immunocompromised patients. Prospective data suggest that antiviral prophylaxis represents an effective and safe alternative to vaccine in patients who would be predicted to have poor responses to influenza vaccine. While there have not been randomized, controlled studies of antiviral therapy completed in solid organ or hematopoietic stem cell patient populations, observational data suggest that early therapy is associated with reduced rates of progression to lower airway involvement, morbidity, and mortality. Further studies are needed to define the optimal regimen, dose, duration, and endpoint to define successful treatment.

Detection of the influenza A(H1N1)pdm09 virus carrying the K-15E, P83S and Q293H mutations in patients who have undergone bone marrow transplant

The 2009 pandemic influenza A(H1N1)pdm09 virus emerged and caused considerable morbidity and mortality in the third world, especially in Brazil. Although circulating strains of A(H1N1)pdm09 are A/California/04/2009-like (CA-04-like) viruses, various studies have suggested that some mutations in the viral hemagglutinin (HA) may be associated with enhanced severity and fatality. This phenomenon is particularly challenging for immunocompromised individuals, such as those who have undergone bone marrow transplant (BMT), because they are more likely to display worse clinical outcomes to influenza infection than non-immunocompromised individuals. We studied the clinical and viral aspects of post-BMT patients with confirmed A(H1N1)pdm09 diagnosis in the largest cancer hospital in Brazil. We found a viral strain with K-15E, P83S and Q293H polymorphisms in the HA, which is presumably more virulent, in these individuals. Despite that, these patients showed only mild symptoms of infection. Our findings complement the discovery of mild cases of infection with the A(H1N1)pdm09 virus with the K-15E, P83S and Q293H mutations in Brazil and oppose other studies that have linked these changes with increased disease severity. These results could be important for a better comprehension of the impact of the pandemic influenza in the context of BMT.

Parainfluenza virus lower respiratory tract disease after hematopoietic cell transplant: viral detection in the lung predicts outcome

BACKGROUND

Parainfluenza virus (PIV) commonly infects patients following hematopoietic cell transplantation (HCT), frequently causing lower respiratory tract disease (LRTD). The definition of LRTD significantly differs among studies evaluating the impact of PIV after HCT.

METHODS

We retrospectively evaluated 544 HCT recipients with laboratory-confirmed PIV and classified LRTD into 3 groups: possible (PIV detection in upper respiratory tract with new pulmonary infiltrates with/without LRTD symptoms), probable (PIV detection in lung with LRTD symptoms without new pulmonary infiltrates), and proven (PIV detection in lung with new pulmonary infiltrates with/without LRTD symptoms).

RESULTS

Probabilities of 90-day survival after LRTD were 87%, 58%, and 45% in possible, probable, and proven cases, respectively. Patients with probable and proven LRTD had significantly worse survival than those with upper respiratory tract infection (probable: hazard ratio [HR], 5.87 [P < .001]; proven: HR, 9.23 [P < .001]), whereas possible LRTD did not (HR, 1.49 [P = .27]). Among proven/probable cases, oxygen requirement at diagnosis, low monocyte counts, and high-dose steroid use (>2 mg/kg/day) were associated with high mortality in multivariable analysis.

CONCLUSIONS

PIV LRTD with viral detection in lungs (proven/probable LRTD) was associated with worse outcomes than was PIV LRTD with viral detection in upper respiratory samples alone (possible LRTD). This new classification should impact clinical trial design and permit comparability of results among centers.

A multicenter evaluation of pandemic influenza A/H1N1 in hematopoietic stem cell transplant recipients

BACKGROUND

Hematopoietic stem cell transplant (HSCT) recipients have increased morbidity from respiratory viral infections. Pandemic influenza A - A(H1N1)/pdm09 - in 2009-2010 was associated with increased severity of illness in patients with underlying co-morbidities including HSCT, but the factors that contribute to severe disease in HSCT patients are not well characterized.

METHODS

We conducted a multicenter review of microbiologically proven influenza A(H1N1)pdm09 in the HSCT population between April 2009 and April 2010 to determine factors that are associated with severe disease.

RESULTS

We identified 37 adult patients (26 allogeneic and 11 autologous HSCT recipients). Median time from transplant to diagnosis was 411 days (range 4 days-14.9 years). Three cases were hospital acquired. Twenty-eight of 37 (75.7%) had confirmed A(H1N1)pdm09. Presumed viral lower respiratory tract infection was present in 12/37 (32.4%) patients. Antiviral therapy was given to 33/37 (89%) patients, primarily oseltamivir (n = 24) and oseltamivir before or after another antiviral (n = 8). Excluding those with nosocomial A(H1N1)pdm09, 18/34 (52.9%) were hospitalized and 6 (33%) required admission to an intensive care unit. Mortality within 30 and 60 days of symptom onset was 7/37 (18.9%) and 11/37 (29.7%), respectively. Factors associated with mortality included nosocomial acquisition (P = 0.023), receipt of mycophenolate mofetil (P = 0.001), or antilymphocyte antibody (P = 0.005) within the past 6 months, reduced-intensity conditioning (P = 0.027), and bacteremia (P = 0.021).

CONCLUSIONS

A(H1N1)pdm09 infection was particularly severe in HSCT recipients, specifically among those receiving augmented immunosuppression for graft-versus-host disease. The high mortality of the nosocomial cases highlights the need for strict infection-control measures in hospitals during influenza outbreaks.

A randomized trial of one versus two doses of influenza vaccine after allogeneic transplantation

Influenza infection after allogeneic hematopoietic cell transplantation (allo-HCT) can result in severe complications. The effectiveness of the annual vaccine depends on age, immune competence, and the antigenic potential of the 3 strains included. We hypothesized that a second vaccine dose, the standard of care for vaccine-naïve children, might improve post hematopoietic cell transplantation (HCT) immune responses. Patients >60 days post-HCT were randomized to receive either 1 (n = 33) or 2 (n = 32) influenza vaccine doses separated by 1 month. The primary endpoint was whether 2 vaccinations induced superior immunity; however, we found no difference. Secondary endpoints were to identify variables associated with responses. Both hemagglutination inhibition (HI; P < .005) and ELISpot responses (P = .03) were greater for patients vaccinated ≥ 1 year posttransplantation. Umbilical cord blood (UCB) recipients showed less IFN-γ responses (P < .001). Interestingly, there was a positive correlation between the total number of CD19(+) cells before vaccination and seroconversion (P = .01) and an inverse correlation for IFN-γ responses (P = .05). Variables not associated with vaccine responses included prevaccine CD4(+) cell counts (total, naïve, or memory), steroid usage at vaccination, age, or conditioning intensity. Time from transplantation to vaccination and absolute CD19(+) cell counts were the strongest predictors of vaccine responses. Methods to improve influenza vaccine responses after allo-HCT are needed.

Influenza vaccination for immunocompromised patients: systematic review and meta-analysis from a public health policy perspective

BACKGROUND

Immunocompromised patients are vulnerable to severe or complicated influenza infection. Vaccination is widely recommended for this group. This systematic review and meta-analysis assesses influenza vaccination for immunocompromised patients in terms of preventing influenza-like illness and laboratory confirmed influenza, serological response and adverse events.

METHODOLOGY/PRINCIPAL FINDINGS

Electronic databases and grey literature were searched and records were screened against eligibility criteria. Data extraction and risk of bias assessments were performed in duplicate. Results were synthesised narratively and meta-analyses were conducted where feasible. Heterogeneity was assessed using I(2) and publication bias was assessed using Begg's funnel plot and Egger's regression test. Many of the 209 eligible studies included an unclear or high risk of bias. Meta-analyses showed a significant effect of preventing influenza-like illness (odds ratio [OR]=0.23; 95% confidence interval [CI]=0.16-0.34; p<0.001) and laboratory confirmed influenza infection (OR=0.15; 95% CI=0.03-0.63; p=0.01) through vaccinating immunocompromised patie nts compared to placebo or unvaccinated controls. We found no difference in the odds of influenza-like illness compared to vaccinated immunocompetent controls. The pooled odds of seroconversion were lower in vaccinated patients compared to immunocompetent controls for seasonal influenza A(H1N1), A(H3N2) and B. A similar trend was identified for seroprotection. Meta-analyses of seroconversion showed higher odds in vaccinated patients compared to placebo or unvaccinated controls, although this reached significance for influenza B only. Publication bias was not detected and narrative synthesis supported our findings. No consistent evidence of safety concerns was identified.

CONCLUSIONS/SIGNIFICANCE

Infection prevention and control strategies should recommend vaccinating immunocompromised patients. Potential for bias and confounding and the presence of heterogeneity mean the evidence reviewed is generally weak, although the directions of effects are consistent. Areas for further research are identified.

Graft-versus-host disease is the major determinant of humoral responses to the AS03-adjuvanted influenza A/09/H1N1 vaccine in allogeneic hematopoietic stem cell transplant recipients

BACKGROUND

Responses to influenza vaccines are poorly characterized in immunocompromised patients. The goal of this study was to assess the efficacy of the AS03-adjuvanted influenza H1N1/A/09 vaccine in allogeneic hematopoietic stem cell transplant recipients.

DESIGN AND METHODS

We enrolled 65 patients and 138 controls in an open prospective study. Controls received one dose and patients 2 doses of the AS03-adjuvanted influenza H1N1/A/09 vaccine at a 3-week interval. Geometric mean titers and seroprotection/seroconversion rates were determined by hemagglutination inhibition before and four weeks after the last immunization. Clinical and biological markers, including immunoglobulins, CD3+, CD4+, CD8+ and naïve CD4+ T-cell counts were assessed in all patients.

RESULTS

Baseline seroprotection rates were low in patients (6.6%) and controls (14.8%). After 2 doses, patients (n=57, 92.3%) achieved similar seroprotection rates (84% vs. 87%, P=0.65) and antibody titers (305 vs. 340, P=0.88) as controls (n=131, 93.9%) after one dose. In univariate analysis, transplant-to-vaccination interval less than 12 months, active graft-versus-host disease, immunosuppressive drugs, hemoglobin less than 12 g/L, lymphopenia less than 1 G/L, IgG less than 4 g/L, IgA less than 0.5 g/L, IgM less than 0.5 g/L and naive CD4+ T cells less than 150/μL were significantly associated with weaker responses. Multivariate analysis identified transplant-to-vaccination interval and active graft-versus-host disease as the most powerful negative predictors of antibody responses (P=0.04 and P=0.002, respectively). Vaccination was well tolerated in both cohorts.

CONCLUSIONS

In allogeneic hematopoietic stem cell transplant recipients, 2 doses of an adjuvanted influenza vaccine elicited comparable responses to a single dose in healthy individuals. However, vaccine responses remained poor in patients with ongoing graft-versus-host disease, supporting the need for additional strategies in this high-risk patient population. (ClinicalTrials.gov Identifier: NCT01022905).