Pandemic (H1N1) 2009 infection in patients with hematologic malignancy

Cumulative incidence and mortality rate of cardiovascular complications due to laboratory-confirmed influenza virus infection: A systematic review and meta-analysis

Influenza infection is associated with cardiovascular complications that range significantly in presentation and severity. The cumulative incidence of cardiovascular complications due to laboratory-confirmed influenza, however, is not reported in the literature. We conducted a systematic review and random-effects meta-analysis to evaluate the cumulative incidence and mortality rate of influenza virus-related cardiovascular complications in hospitalized patients. We searched the PubMed and EMBASE databases for studies reporting acute myocardial infarction (AMI), heart failure (HF), arrhythmia of any kind, stroke or transient ischemic attack (TIA), and myocarditis in hospitalized patients with laboratory-confirmed influenza virus infection. Prospective studies, retrospective cohort studies, and randomized controlled trials (RCTs) were included in the analysis. We followed the PRISMA checklist and used 95% confidence intervals (CIs) to report meta-analysis outcomes. This study was registered on PROSPERO (CRD42023427849). After retrieving 2803 studies, we identified 19 studies (18 observational and 1 RCT) with relevant data, and we included 6936 patients in our analysis, of whom 690 (9.9%) developed a cardiovascular outcome of interest. The cumulative incidence of HF was 17.47% (95% CI: 5.06%-34.54%), arrhythmia of any kind 6.12% (95% CI: 0.00%-21.92%), myocarditis 2.56% (95% CI: 0.66%-5.38%), AMI 2.19% (95% CI: 1.03%-3.72%), and stroke or TIA 1.14% (95% CI: 0.00%-4.05%). The in-hospital mortality rate from cardiovascular events was 1.38% (95% CI: 0.00%-4.80%). Cardiovascular complications occur in patients with influenza virus infection, with the cumulative incidence of specific cardiac manifestations varying considerably (1.51%-17.47%). Preventive strategies and close clinical monitoring after infection remain a priority.

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 in patients with cancer after 2009 pandemic AH1N1: An 8-year follow-up study in Mexico

BACKGROUND

Immunosupressed patients are at high risk of influenza-related complications. Influenza AH1N1 has been hypothesized to induce worse outcomes in patients with malignancies, but after the A(H1N1)pdm09 few publications have analyzed the presentation and complications related to influenza afterward.

OBJECTIVES

We aimed to describe the characteristics, risk factors, and outcomes of influenza in an oncologic center after the 2009 pandemic and to compare our case distribution to the National community acquired influenza databases in Mexico and the United States.

METHODS

We reviewed the cases of confirmed influenza in patients with cancer from an oncological center in Mexico from April 2009 to April 2017. Data on severity and influenza type, malignancy, comorbidities, and outcomes were recorded. We correlated data between the Centers for Disease Control and Prevention (CDC) in the United States and SISVEFLU (Influenza Surveillance Program) in Mexico.

RESULTS

One hundred eighty-eight patients were included; 75 (39.9%) had a solid neoplasm and 113 (60.1%) had hematologic malignancies. AH1N1 was the most frequent influenza type (54.2%). Patients with hematologic malignancies had more pneumonia (55% vs 25%, P < .001), needed more hospitalizations (75% vs 39% P < .001), had higher all-cause mortality at 30 days (20% vs 9% P = .048) and influenza-associated mortality (17% vs 7% P = .041). Thirty (16%) patients died within 30 days, and 24 (12.7%) were related to influenza. Influenza type was not associated with worse outcomes. Yearly occurrence of influenza reported by the CDC and SISVEFLU showed a significant correlation (ρ = 0.823, P = .006).

CONCLUSIONS

AH1N1 was the dominant serotype. Patients with hematologic malignancies had more severe influenza and presented worse outcomes. Annual SISVEFLU and CDC surveillance information showed a similar distribution of cases along time but influenza serotypes did not match for all seasons.

Respiratory Viral Infections in Transplant Recipients

Respiratory viral infections (RVIs) are common among the general population; however, these often mild viral illnesses can lead to serious morbidity and mortality among recipients of hematopoietic stem cell and solid organ transplantation. The disease spectrum ranges from asymptomatic or mild infections to life-threatening lower respiratory tract infection or long-term airflow obstruction syndromes. Progression to lower respiratory tract infection or to respiratory failure is determined by the intrinsic virulence of the specific viral pathogen as well as various host factors, including the type of transplantation, status of the host’s immune dysfunction, the underlying disease, and other comorbidities. This chapter focuses on the epidemiology, clinical manifestations, diagnosis, and management of RVIs in this susceptible population and includes respiratory syncytial virus, parainfluenza virus, human metapneumovirus, influenza virus, human coronavirus, and human rhinovirus. The optimal management of these infections is limited by the overall paucity of available treatment, highlighting the need for new antiviral drug or immunotherapies.

Influenza in patients with hematological malignancies: Experience at two comprehensive cancer centers

The burden of influenza infections in patients with hematological malignancies (HMs) is not well defined. We describe the clinical presentation and associated outcomes of influenza at two comprehensive cancer centers (center 1 in the United States and center 2 in Mexico). Clinical and laboratory data on patients with HMs and influenza infection diagnosed from April 2009 to May 2014 at the two centers were reviewed retrospectively. A total of 190 patients were included, the majority were male (63%) with a median age of 49 years (range, 1-88 years), and had active or refractory HMs (76%). Compared to center 1, patients in center 2 were significantly sicker (active cancer, decreased albumin levels, elevated creatinine levels, or hypoxia at influenza diagnosis) and experienced higher lower respiratory tract infection (LRI) rate (42% vs 7%; P < 0.001). In multivariable logistic regression analysis (odds ratio, 95% confidence interval), leukemia, (3.09, 1.23-7.70), decreased albumin level (3.78, 1.55-9.20), hypoxia at diagnosis (14.98, 3.30-67.90), respiratory co-infection (5.87, 1.65-20.86), and corticosteroid use (2.71, 1.03-7.15) were significantly associated with LRI; and elevated creatinine level (3.33, 1.05-10.56), hypoxia at diagnosis (5.87, 1.12-30.77), and respiratory co-infection (6.30, 1.55-25.67) were significantly associated with 60 day mortality in both centers. HM patients with influenza are at high risk for serious complications such as LRI and death, especially if they are immunosuppressed. Patients with respiratory symptoms should seek prompt medical care during influenza season.

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.

Immunogenicity of a monovalent influenza A(H1N1)pdm09 vaccine in patients with hematological malignancies

Patients with hematological malignancies have high risk for morbidity and mortality from influenza. This study was conducted to evaluate the immunogenicity and reactogenicity of an influenza A(H1N1)pdm09 vaccine among such subjects. Fifty subjects were vaccinated twice during the 2009-2010 season. The antibody response was expressed in terms of mean fold rise (MFR) of geometric mean titer, seroresponse proportion (sR), and seroprotection proportion (sP). The first vaccination induced only a small response, and additional antibody was acquired after the second dose (MFR 2.3 and 3.9, sR 32% and 54%, and sP 30% and 48% after the first and the second vaccination, respectively). Rituximab treatment showed an especially inhibitory effect (MFR 1.3, sR 9% and sP 0%). When analyzed using logistic regression models, only rituximab was found to have an independent effect; the adjusted odds ratio for sR was 0.09 (P = 0.05). Influenza vaccination of patients with hematological malignancies resulted in adepuate response, and the second vaccination induced additional antibody. It is therefore recommended to vaccinate this group twice.

Prospective Evaluation of 2009 H1N1 Influenza A in Patients Admitted with Fever to an Oncology Unit

We prospectively evaluated all oncology inpatients for 2009 H1N1 influenza virus. All patients recovered completely. Evaluating all oncology patients with fever for influenza involved overtreatment of influenza-negative patients and involved a significant infection control burden. However, early antiviral intervention could have contributed to a favorable outcome.

Analysis of fatal cases of pandemic influenza A (H1N1) virus infections in pediatric patients with leukemia

BACKGROUND

Pandemic influenza A/H1N1/2009 virus usually causes mild illness in healthy children. Chronic medical conditions are recognized as increasing the risk for complications of influenza virus infection. Although most studies including children with acute leukemia and H1N1 virus have reported no deaths, some anectodal reports with low patient numbers have reported mortality rates as high as 28.5%. Here, we report patients with leukemia and H1N1 virus and review the literature.

METHODS

Medical records of all children with leukemia and H1N1 virus in our institution were reviewed for demographic, clinical, and laboratory data. We also carried out a systematic review of the English-language literature. Among the 24 articles found, only patients with leukemia and pandemic H1N1 infections were reviewed by two independent reviewers.

RESULTS

Eight of 98 children who received chemotherapy for leukemia were diagnosed with pandemic H1N1 infection. One developed pneumonia and acute respiratory distress syndrome (ARDS) and died. Another one developed hemophagocytic lymphohistiocytosis (HLH) and died due to secondary infection during the 6th week of treatment for HLH. In our study, 2 of 8 patients had a fatal course (25%), compared with an overall mortality of 2.5% in the studies retrieved from PubMed (6/232).

CONCLUSION

Pandemic H1N1 influenza virus caused mortality in patients with ARDS or HLH; an unexpected finding for pandemic H1N1 (2009) influenza virus. Thus, for children with leukemia and infected with H1N1 virus, short- and long-term complications should be kept in mind during evaluation.

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.

Unchanged severity of influenza A(H1N1)pdm09 infection in children during first postpandemic season

Improvement is needed in preventing severe disease and nosocomial transmission in children beyond pandemic situations.

We conducted a nationwide hospital-based prospective study in Germany of influenza A(H1N1)pdm09 cases among children <15 years of age admitted to pediatric intensive care units and related deaths during the 2009–10 pandemic and the 2010–11 postpandemic influenza seasons. We identified 156 eligible patients: 112 in 2009–10 and 44 in 2010–11. Although a shift to younger patients occurred in 2010–11 (median age 3.2 vs. 5.3 years), infants <1 year of age remained the most affected. Underlying immunosuppression was a risk factor for hospital-acquired infections (p = 0.013), which accounted for 14% of cases. Myocarditis was predictive of death (p = 0.006). Of the 156 case-patients, 17% died; the difference between seasons was not significant (p = 0.473). Our findings stress the challenge of preventing severe postpandemic influenza infection in children and the need to prevent nosocomial transmission of influenza virus, especially in immunosuppressed children.

Clinical characteristics and outcome associated with pandemic (2009) H1N1 influenza infection in patients with hematologic malignancies: a retrospective cohort study

Pandemic H1N1 (pH1N1) influenza has been associated with a worldwide outbreak of febrile respiratory illness. Although impaired immunity, such as that caused by hematologic malignancy, has been identified as a risk factor for severe infection with this virus, the course of this infection has not been adequately characterized in patients with underlying hematologic malignancy in comparison with immune competent controls. We report our experience with severe pH1N1 infection in patients with hematologic cancers and compare this group to non-immunosuppressed patients. Data were retrospectively collected on all patients admitted to our institution with confirmed pH1N1 infection. Clinical characteristics, treatments and outcomes were compared between patients with hematologic malignancies and non-immunocompromised controls. Fifteen patients with hematologic malignancy and 49 controls were identified. The control group had higher baseline rates of asthma (p = 0.01) and smoking (p = 0.05) at baseline. Clinical features of infection in the two groups were similar, except for a higher prevalence of abnormalities on chest imaging in the group with malignancy (p = 0.05). No statistically significant difference in mortality was observed between the groups. Mean duration of hospitalization (22.1 days vs. 9.2 days, p = 0.04) and duration of antiviral treatment (9.9 days vs. 6.7 days, p < 0.05) were greater in the hematologic malignancy group. Hospitalized patients with hematologic malignancies with pH1N1 infection had greater durations of hospitalization and treatment than non-immunocompromised controls, possibly reflecting decreased clearance of the virus as a consequence of impaired immunity.

A prospective study of the factors shaping antibody responses to the AS03-adjuvanted influenza A/H1N1 vaccine in cancer outpatients

PURPOSE

To identify the determinants of antibody responses to adjuvanted influenza A/H1N1/09 vaccines in a cohort of cancer outpatients.

PATIENTS AND METHODS

Patients with cancer and controls were enrolled in a prospective single-center field study. Two doses of AS03-adjuvanted pandemic influenza vaccine were administered to patients and one dose was administered to controls. Antibody responses were measured using hemagglutination inhibition and confirmed by microneutralization. Geometric mean titers (GMTs) and seroprotection rates (defined as GMTs ≥40) were compared.

RESULTS

Immunizations were safe and well tolerated in 197 cancer patients (lymphoma, 57; glioma, 26; lung or head and neck, 37; gastrointestinal, 41; breast, 36) and 138 controls. Similar seroprotection rates (82.3% versus 87%) and GMTs (336.9 versus 329.9) were achieved after two doses of adjuvanted vaccine in cancer patients and one dose in controls. Univariate analyses identified older age, prior immunization against seasonal influenza, lymphoma, CD4 count, active chemotherapy, and rituximab and steroid treatments as being associated with weaker antibody responses. However, only age and chemotherapy plus rituximab remained independent determinants of vaccine responses in multivariate analyses.

CONCLUSIONS

Two doses of AS03-adjuvanted influenza vaccine elicited potent antibody responses in most cancer patients despite ongoing chemotherapy, with the exception of rituximab-induced B-cell depletion. Oncology patients treated in an outpatient setting benefit from preventive vaccination against influenza with adjuvanted vaccines.

Changing epidemiology of respiratory viral infections in hematopoietic cell transplant recipients and solid organ transplant recipients

PURPOSE OF REVIEW

New respiratory viruses have been discovered in recent years and new molecular diagnostic assays have been developed that improve our understanding of respiratory virus infections. This article will review the changing epidemiology of these viruses after hematopoietic stem cell and solid organ transplantation.

RECENT FINDINGS

Respiratory viruses are frequently detected in transplant recipients. A number of viruses have been newly discovered or emerged in the last decade, including human metapneumovirus, human bocavirus, new human coronaviruses and rhinoviruses, human polyomaviruses, and a new 2009 pandemic strain of influenza A/H1N1. The potential for these viruses to cause lower respiratory tract infections after transplantation varies, and is greatest for human metapneumovirus and H1N1 influenza, but appears to be limited for the other new viruses. Acute and long-term complications in hematopoietic and solid organ transplant recipients are active areas of research.

SUMMARY

Respiratory viral infections are frequently associated with significant morbidity following transplantation and are therefore of great clinical and epidemiologic interest. As new viruses are discovered, and more sensitive diagnostic methods are developed, defining the full impact of emerging respiratory viruses in transplant recipients must be elucidated by well designed clinical studies.