Immune response to pandemic H1N1 2009 influenza a vaccination in pediatric liver transplant recipients

Travel and biologic therapy: travel-related infection risk, vaccine response and recommendations

BACKGROUND

Biologic therapy has revolutionized the management of refractory chronic autoimmune and auto-inflammatory disease, as well as several malignancies, providing rapid symptomatic relief and/or disease remission. Patients receiving biologic therapies have an improved quality of life, facilitating travel to exotic destinations and potentially placing them at risk of a range of infections. For each biologic agent, we review associated travel-related infection risk and expected travel vaccine response and effectiveness.

METHODS

A PUBMED search [vaccination OR vaccine] AND/OR ['specific vaccine'] AND/OR [immunology OR immune response OR response] AND [biologic OR biological OR biologic agent] was performed. A review of the literature was performed in order to develop recommendations on vaccination for patients in receipt of biologic therapy travelling to high-risk travel destinations.

RESULTS

There is a paucity of literature in this area, however, it is apparent that travel-related infection risk is increased in patients on biologic therapy and when illness occurs they are at a higher risk of complication and hospitalization. Patients in receipt of biologic agents are deemed as having a high level of immunosuppression-live vaccines, including the yellow fever vaccine, are contraindicated. Inactivated vaccines are considered safe; however, vaccine response can be attenuated by the patient's biologic therapy, thereby resulting in reduced vaccine effectiveness and protection.

CONCLUSIONS

Best practice requires a collaborative approach between the patient's primary healthcare physician, relevant specialist and travel medicine expert, who should all be familiar with the immunosuppressive and immunomodulatory effects resulting from the biologic therapies. Timing of vaccines should be carefully planned, and if possible, vaccination provided well before established immunosuppression.

Travel vaccination recommendations and endemic infection risks in solid organ transplantation recipients

BACKGROUND

Solid organ transplant (SOT) recipients are often heavily immunosuppressed and consequently at risk of serious illness from vaccine preventable viral and bacterial infections or with endemic fungal and parasitic infections. We review the literature to provide guidance regarding the timing and appropriateness of vaccination and pathogen avoidance related to the immunological status of SOT recipients.

METHODS

A PUBMED search ([Vaccination OR vaccine] AND/OR ["specific vaccine"] AND/OR [immunology OR immune response OR cytokine OR T lymphocyte] AND transplant was performed. A review of the literature was performed in order to develop recommendations on vaccination for SOT recipients travelling to high-risk destinations.

RESULTS

Whilst immunological failure of vaccination in SOT is primarily the result of impaired B-cell responses, the role of T-cells in vaccine failure and success remains unknown. Vaccination should be initiated at least 4 weeks prior to SOT or more than 6 months post-SOT. Avoidance of live vaccination is generally recommended, although some live vaccines may be considered in the specific situations (e.g. yellow fever). The practicing physician requires a detailed understanding of region-specific endemic pathogen risks.

CONCLUSIONS

We provide a vaccination and endemic pathogen guide for physicians and travel clinics involved in the care of SOT recipients. In addition, recommendations based on timing of anticipated immunological recovery and available evidence regarding vaccine immunogenicity in SOT recipients are provided to help guide pre-travel consultations.

Changing face of vaccination in immunocompromised hosts

Infection prevention is a key component of care and an important determinant of clinical outcomes in a diverse population of immunocompromised hosts. Vaccination remains a fundamental preventative strategy, and clear guidelines exist for the vaccination of immunocompromised individuals and close contacts. Unfortunately, adherence to such guidelines is frequently suboptimal, with consequent missed opportunities to prevent infection. Additionally, vaccination of immunocompromised individuals is known to produce responses inferior to those observed in immunocompetent hosts. Multiple factors contribute to this finding, and developing improved vaccination strategies for those at high risk of infectious complications remains a priority of care providers. Herein, we review potential factors contributing to vaccine outcomes, focusing on host immune responses, and propose a means for applying modern, innovative systems biology technology to model critical determinants of vaccination success. With influenza vaccine in solid organ transplants used as a case in point, novel means for stratifying individuals using a host "immunophenotype" are explored, and strategies for individualizing vaccine approaches tailored to safely optimize vaccine responses in those most at risk are discussed.

Immunogenicity of pandemic influenza A H1N1/2009 adjuvanted vaccine in pediatric solid organ transplant recipients

The aim of this study was to assess the immunogenicity of a vaccine against this virus in a prospective cohort of transplanted pediatric patients without previous influenza infection who received one dose of MF59®-adjuvanted pandemic H1N1/2009 vaccine. Seventeen patients who were being regularly followed up at the Outpatient Clinic of the Children's Transplant Unit (liver and kidney transplantation) in Hospital Universitari Vall d'Hebron (Barcelona) were included. Seroconversion was demonstrated in 15 of 17 (88.2%) vaccinated children. There were no rejection episodes or major adverse events. The MF59(®) -adjuvanted pandemic H1N1/2009 vaccine was safe and elicited an adequate response.

Management of influenza infection in solid-organ transplant recipients: consensus statement of the Group for the Study of Infection in Transplant Recipients (GESITRA) of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC) and the Spanish Network for Research in Infectious Diseases (REIPI)

BACKGROUND

Solid organ transplant (SOT) recipients are at greater risk than the general population for complications and mortality from influenza infection.

METHODS

Researchers and clinicians with experience in SOT infections have developed this consensus document in collaboration with several Spanish scientific societies and study networks related to transplant management. We conducted a systematic review to assess the management and prevention of influenza infection in SOT recipients. Evidence levels based on the available literature are given for each recommendation. This article was written in accordance with international recommendations on consensus statements and the recommendations of the Appraisal of Guidelines for Research and Evaluation II (AGREE II).

RESULTS

Recommendations are provided on the procurement of organs from donors with suspected or confirmed influenza infection. We highlight the importance of the possibility of influenza infection in any SOT recipient presenting upper or lower respiratory symptoms, including pneumonia. The importance of early antiviral treatment of SOT recipients with suspected or confirmed influenza infection and the necessity of annual influenza vaccination are emphasized. The microbiological techniques for diagnosis of influenza infection are reviewed. Guidelines for the use of antiviral prophylaxis in inpatients and outpatients are provided. Recommendations for household contacts of SOT recipients with influenza infection and health care workers in close contact with transplant patients are also included. Finally antiviral dose adjustment guidelines are presented for cases of impaired renal function and for pediatric populations.

CONCLUSIONS

The latest scientific information available regarding influenza infection in the context of SOT is incorporated into this document.

Low seroconversion after one dose of AS03-adjuvanted H1N1 pandemic influenza vaccine in solid-organ transplant recipients

BACKGROUND

Immunocompromised individuals are more susceptible to complications produced by influenza infection. As a result, solid-organ transplant (SOT) recipients were targeted as a priority group to receive AS03-adjuvanted H1N1 influenza vaccine during 2009.

OBJECTIVE

To evaluate seroconversion after one dose of adjuvanted pandemic influenza H1N1 (pH1N1) vaccine in SOT recipients.

METHODS

Adult SOT recipients were enrolled to receive one 3.75 μg dose of adjuvanted pH1N1 vaccine. Serological status was tested using a hemagglutination inhibition assay before and two and four weeks postvaccination.

RESULTS

The five SOT recipients (one liver, two kidney and two lung transplants) had a median age of 50 years (range 36 to 53 years), and three were male, who were a median time of three years (range two months to 15 years) post-transplant. All patients were on a double or triple immunosuppressive regimen. The prevaccination pH1N1 titre was 1:10 in four patients and 1:40 in one patient. Seroprotection was observed only in one patient, with a rise in titre from 1:40 at baseline to 1:320 at both two and four weeks after vaccination. This lung transplant recipient had documented previous infection with pH1N1.

CONCLUSION

Results of the present small study call into question whether one dose of adjuvanted pH1N1 vaccine can provide seroprotection in SOT recipients.

Respiratory viral infections in pediatric solid organ and hematopoietic stem cell transplantation

Respiratory viruses are common in children, including pediatric recipients of both solid organ transplantation and hematopoietic stem cell transplantation. The prevalence and risk factors in each of these groups are reviewed. Furthermore, associated morbidity and mortality in pediatric transplant recipients with respiratory viral infections are addressed. The literature on specific prevention and treatment options for respiratory syncytial virus, adenovirus, influenza, and other respiratory viruses in pediatric solid organ and hematopoietic stem cell transplant recipients is reported.

Influenza vaccination coverage rate in children: reasons for a failure and how to go forward

Based on an increasingly extensive literature expressing the large interest in the field, this paper gives an overview of different aspects of influenza prevention in children. It relies on paradoxes. First, the heaviest part of the burden is well demonstrated in the youngest infants by numerous epidemiological data elsewhere. On the contrary, with older children, the prevention by influenza vaccines is more efficacious-without notable side effects. Second, the available TIV vaccines are 60 years old and the requests of registration and regulation of vaccines have evolved. There is a specific need in children: it is time to re-discuss the pragmatic utilization of influenza vaccines (full dose in the youngest patient? More flexibility regarding the interval between the two required doses in vaccine-naïve children), and to change from a compassionate use to a targeted research and adapted vaccines considering the limits of TIV in the youngest children. Third, influenza virus transmission is the highest in children in semi-close communities (day-care centers, schools), diffusing to households and more largely to the population. A restricted policy on high risk groups (roughly 10% in a pediatric population, all medical conditions including asthma, for whom influenza vaccine coverage is a 15-75% range) is far below the estimated threshold of 45% coverage rate to limit the virus circulation by an indirect impact during seasonal epidemics. Fourth, public health decisions in the vaccination field are usually taken from top to bottom. The pandemic A/H1N1 has toughly demonstrated that "forgetting" about the perception and expectations of the public and the parents nearly created conflicts and at least a strong resistance impeding the quality of a program worked on for a long time ahead. Fifth, and not the least, HCPs are pivotal in influenza vaccination mostly trusted by the parents. Too often, they are not backed by a national and clear support and they need to reinforce their knowledge on the disease and the vaccines.