Pandemic influenza A H1N1 vaccine in recipients of solid organ transplants: Immunogenicity and tolerability outcomes after vero cell derived, non-adjuvanted, whole-virion vaccination

Vaccination and their importance for lung transplant recipients in a COVID-19 world

INTRODUCTION

Lung transplant patients are immunocompromised because of the medication they receive to prevent rejection, and as a consequence are susceptible to (respiratory) infections. Adequate vaccination strategies, including COVID-19 vaccination, are therefore needed to minimize infection risks.

AREAS COVERED

The international vaccination guidelines for lung transplant patients are reviewed, including the data on immunogenicity and effectivity of the vaccines. The impact on response to vaccination of the various categories of immunosuppressive drugs, used in the posttransplant period, on response to vaccination is described. A number of immunosuppressive and/or anti-inflammatory drugs also is used for controlling the immunopathology of severe COVID-19. Current available COVID-19 vaccines, both mRNA or adenovirus based are recommended for lung transplant patients.

EXPERT OPINION

In order to improve survival and quality of life, infections of lung transplant patients should be prevented by vaccination. When possible, vaccination should start already during the pre-transplantation period when the patient is on the waiting list. Booster vaccinations should be given post-transplantation, but only when immunosuppression has been tapered. Vaccine design based on mRNA technology could allow the design of an array of vaccines against other respiratory viruses, offering a better protection for lung transplant patients.

Short-Fragment DNA Residue from Vaccine Purification Processes Promotes Immune Response to the New Inactivated EV71 Vaccine by Upregulating TLR9 mRNA

To reduce potential oncogenic long genomic DNA in vaccines, nuclease treatment has been applied in the purification processes. However, this action increased the residue of short-fragment DNA and its effect on vaccine potency was still elusive. In this study, we found residual sf-DNA in an inactivated EV71 vaccine could enhance humoral immune response in mice. Ag stimulation in vitro and vaccine injection in vivo revealed that TLR9 transcription level was elevated, indicating that sf-DNA could activate TLR9. These new findings will help us to understand the molecular mechanism induced by vero-cell culture-derived vaccines.

Vero cell culture-derived pandemic influenza vaccines: preclinical and clinical development

Several subtypes of influenza A viruses with pandemic potential are endemic in bird populations throughout Asia, Africa and the Middle East, and evidence suggests that these viruses are adapting to the mammalian host. As emphasized by the high mortality rate of humans infected with H5N1 viruses, this situation presents a substantial risk to global human health. The Vero cell culture platform has been used to develop whole-virus influenza vaccines that provide broad cross-clade protection against viruses with pandemic potential, at low antigen doses, without the requirement for adjuvantation. The safety and immunogenicity of these vaccines has been demonstrated in studies with more than 10,000 individuals, including healthy adult and elderly subjects, children and various risk groups. These Vero cell-derived vaccines are licensed for prepandemic and pandemic use. The Vero platform is also being explored to develop next-generation live-attenuated and recombinant vaccines.

HIV-infected patients show impaired cellular immune response to influenza vaccination compared to healthy subjects

Detailed data on cellular immune response to influenza vaccination in HIV-infected patients are lacking. We analyzed cellular (IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, IFN-γ, TNF-α, GM-CSF) and humoral (IgG and IgM) immune response in 81 HIV-infected and 30 HIV-negative subjects, before (T0) and 4 weeks (T1) after receiving a single dose of trivalent MF59-adjuvanted influenza vaccine. No difference in humoral response (IgG or IgM) was demonstrated between the two groups. While an increase in most cytokines from T0 to T1 was observed in HIV-uninfected subjects, cytokines production did not significantly increased in HIV-infected patients. Exploring Th1 response, higher CD8 cells count was significantly associated with lower post-vaccination IFNγ levels, while a higher CD4 cells count was associated with a greater response. Exploring Th2 response, higher HIV viral load was significantly associated with reduced post-vaccination IL-10 levels. In conclusion, in HIV-infected patients influenza vaccination could have good efficacy in sustaining humoral response but cellular response appeared impaired.

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.

Pre- and post-pandemic prevalence of antibodies to the 2009 pandemic influenza A (H1N1) virus in Austrian adults

Antibody prevalence to the 2009 pandemic influenza A (H1N1) virus was determined in a sample of the Austrian population to assess the post-pandemic seropositivity rate, the infection attack rate, and the proportion of subclinical infections during the 2009/2010 influenza pandemic in Austrian adults. A total of 480 sera from individuals aged between 18 and 57 years from all nine federal states of Austria were collected between April and June 2010. Information on demographic characteristics, vaccination history, and history of suspected or verified influenza virus infection was ascertained. Antibodies were determined using a commercial ELISA and compared with 80 age-matched adult sera collected before the pandemic began. The overall seropositivity rate was 28% and was highest among young adults aged 18-29 years, followed by adults aged 50-57 years. Among seropositive unvaccinated individuals, infection was asymptomatic in more than 80%. Extrapolation to the overall Austrian adult population indicates that more than 1.3 million persons aged 18-57 years became infected in 2009. Compared with the pre-pandemic seropositivity rate, the infection rate was highest among young adults but low in those aged 30-57 years. Among 69 individuals previously vaccinated with the 2009 pandemic influenza A (H1N1) virus, 71% had specific antibodies. The study demonstrates that infection rates based on surveillance of clinical cases considerably underestimated the infection attack rate during the 2009 H1N1 pandemic in Austria and that vaccination against this virus elicited long-lasting seropositivity in more than 70% of adults.

Preflucel®: a Vero-cell culture-derived trivalent influenza vaccine

Vaccination is the principal means to reduce the impact of influenza infection. Effective vaccination programs require a reliable and safe production system. Traditionally, influenza vaccines are produced in embryonated chicken eggs. Over the last two decades, new cell culture-derived vaccines have been licensed and manufactured, and other vaccines are still in various phases of development. Vero cells have been used for the development of a wide variety of vaccines including influenza vaccines. Pandemic and avian influenza vaccines derived from Vero cells have been shown to be well tolerated and immunogenic in animal and Phase I-II clinical studies. A Phase III randomized, double-blind, placebo-controlled trial of a trivalent influenza vaccine produced in Vero-cell culture was conducted in 7250 adults aged 18-49 years. Overall protective efficacy for antigenically matched influenza vaccine was 78.5%. The vaccine was well tolerated with no treatment-related serious adverse events and compared favorably with egg-derived vaccines from previous trials. Vero-cell-derived influenza vaccines have the potential to be an important parts of the influenza vaccine strategy, especially if an avian-derived strain becomes predominant or the demand outstrips the capacity of egg-based production systems.

Poor seroprotection but allosensitization after adjuvanted pandemic influenza H1N1 vaccine in kidney transplant recipients

BACKGROUND

Seasonal and pandemic influenza virus infections in renal transplant patients are associated with poor outcomes. During the pandemic of 2009-2010, the AS03-adjuvanted monovalent H1N1 influenza vaccine was recommended for transplant recipients, although its immunogenicity in this population was unknown. We sought to determine the safety and immunogenicity of an adjuvant-containing vaccine against pandemic influenza A H1N1 2009 (pH1N1) administered to kidney transplant recipients.

METHODS

We prospectively enrolled 124 adult kidney transplant recipients in the fall of 2009 at two transplant centers. Cohort 1 (n = 42) was assessed before and after pH1N1 immunization, while Cohort 2 (n = 82) was only assessed post immunization. Humoral response was measured by the hemagglutination inhibition assay. Vaccine safety was assessed by adverse event reporting, graft function, and human leukocyte antigen (HLA) alloantibody measurements.

RESULTS

Cohort 1 had a low rate of baseline seroprotection to pH1N1 (7%) and a low rate of seroprotection after immunization (31%). No patient <6 months post transplant (n = 5) achieved seroprotection. Seroprotection rate was greater in patients receiving double as compared with triple immunosuppression (80% vs. 24%, P = 0.01). In Cohort 2, post-immunization seroprotection was 35%. In both cohorts, no confirmed cases of pH1N1 infection occurred. No difference was seen in estimated glomerular filtration rate before (54.3 mL/min/1.73 m(2) ) and after (53.8 mL/min/1.73 m(2) ) immunization, and no acute rejections had occurred after immunization at last follow-up. In Cohort 1, 11.9% of patients developed new anti-HLA antibodies.

CONCLUSION

An adjuvant-containing vaccine to pH1N1 provided poor seroprotection in renal transplant recipients. Receiving triple immunosuppression was associated with a poor seroresponse. Vaccination appeared safe, but some patients developed new anti-HLA antibodies post vaccination. Alternative strategies to improve vaccine responses are necessary.

Higher memory responses in HIV-infected and kidney transplanted patients than in healthy subjects following priming with the pandemic vaccine

Background

Memory responses require immune competence. We assessed the influence of priming with AS03-adjuvanted pandemic vaccine (Pandemrix®) on memory responses of HIV patients, kidney recipients (SOT) and healthy controls (HC).

Method

Participants (HIV: 197, SOT: 53; HC: 156) were enrolled in a prospective study and 390/406 (96%) completed it. All had been primed in 2009/2010 with 1 (HC) or 2 (patients) doses of Pandemrix®, and were boosted with the 2010/2011 seasonal influenza vaccine. Geometric mean titres and seroprotection rates were measured 12 months after priming and 4 weeks after boosting. Primary and memory responses were directly compared in 191 participants (HCW: 69, HIV: 71, SOT: 51) followed during 2 consecutive seasons.

Results

Most participants (HC: 77.8%, HIV: 77.6%, SOT: 66%) remained seroprotected at 12 months post-priming. Persisting A/09/H1N1 titers were high in HIV (100.2) and HC (120.1), but lower in SOT (61.4) patients. Memory responses reached higher titers in HIV (507.8) than in HC (253.5) and SOT (136.9) patients. Increasing age and lack of HAART reduced persisting and memory responses, mainly influenced by residual antibody titers. Comparing 2009/2010 and 2010/2011 titers in 191 participants followed for 2 seasons indicated lower post-2010/2011 titers in HC (240.2 vs 313.9), but higher titers in HIV (435.7 vs 338.0) and SOT (136 vs 90.3) patients.

Conclusions

Priming with 2 doses of Pandemrix® elicited persistent antibody responses and even stronger memory responses to non-adjuvanted seasonal vaccine in HIV patients than 1 dose in healthy subjects. Adjuvanted influenza vaccines may improve memory responses of immunocompromised patients.

Trial Registration

ClinicalTrials.gov NCT01022905

Immunogenicity and tolerability after two doses of non-adjuvanted, whole-virion pandemic influenza A (H1N1) vaccine in HIV-infected individuals

Background

During the influenza pandemic of 2009/10, the whole-virion, Vero-cell-derived, inactivated, pandemic influenza A (H1N1) vaccine Celvapan® (Baxter) was used in Austria. Celvapan® is adjuvant-free and was the only such vaccine at that time in Europe. The objective of this observational, non-interventional, prospective single-center study was to evaluate the immunogenicity and tolerability of two intramuscular doses of this novel vaccine in HIV-positive individuals.

Methods and Findings

A standard hemagglutination inhibition (HAI) assay was used for evaluation of the seroconversion rate and seroprotection against the pandemic H1N1 strain. In addition, H1N1-specific IgG antibodies were measured using a recently developed ELISA and compared with the HAI results. Tolerability of vaccination was evaluated up to one month after the second dose. A total of 79 HIV-infected adults with an indication for H1N1 vaccination were evaluated. At baseline, 55 of the 79 participants had an HAI titer ≥1∶40 and two patients showed a positive IgG ELISA. The seroconversion rate was 31% after the first vaccination, increasing to 41% after the second; the corresponding seroprotection rates were 92% and 83% respectively. ELISA IgG levels were positive in 25% after the first vaccination and in 37% after the second. Among the participants with baseline HAI titers <1∶40, 63% seroconverted. Young age was clearly associated with lower HAI titers at baseline and with higher seroconversion rates, whereas none of the seven patients >60 years of age had a baseline HAI titer <1∶40 or seroconverted after vaccination. The vaccine was well tolerated.

Conclusion

The non-adjuvanted pandemic influenza A (H1N1) vaccine was well tolerated and induced a measurable immune response in a sample of HIV-infected individuals.

Pre-vaccination immunity and immune responses to a cell culture-derived whole-virus H1N1 vaccine are similar to a seasonal influenza vaccine

BACKGROUND

Immune responses to novel pandemic influenza vaccines may be influenced by previous exposure to antigenically similar seasonal strains.

METHODS

An open-label, randomized, phase I/II study was conducted to assess the immunogenicity and safety of a non-adjuvanted, inactivated whole-virus H1N1 A/California/07/2009 vaccine. 408 subjects were stratified by age (18-59 and >60 years) and randomized 1:1 to receive two vaccinations with either 3.75 or 7.5 μg hemagglutinin antigen 21 days apart. Safety, immunogenicity and the influence of seasonal influenza vaccination and antibody cross-reactivity with a seasonal H1N1 strain was assessed.

RESULTS

A single vaccination with either dose induced substantial increases in H1N1 A/California/07/2009 hemagglutination inhibition (HI) and neutralizing (MN) antibody titers in both adult and elderly subjects. A single 7.5 μg dose induced seroprotection rates of 86.9% in adults and 75.2% in elderly subjects. Two 7.5 μg vaccinations induced seroprotection rates in adult and elderly subjects of 90.9% and 89.1%, respectively. The robust immune response to vaccination was confirmed by analyses of neutralizing antibody titers. Both HI and MN antibodies persisted for ≥ 6 months post-vaccination. Between 34% and 49% of subjects had seroprotective levels of H1N1 A/California/07/2009 antibodies at baseline. Higher baseline HI titers were associated with receipt of the 2008-09 or 2009-10 seasonal influenza vaccine. High baseline A/California/07/2009 neutralizing antibody titers were also associated with high baseline titers against A/New Caledonia/20/99, a seasonal H1N1 strain which circulated and was included in the seasonal vaccine from 2000-01 to 2006-07. Pre-adsorption with A/H1N1/New Caledonia/20/99 antigen reduced A/H1N1/California/07/2009 baseline titers in 55% of tested sera. The vaccine was well tolerated with low rates of fever.

CONCLUSIONS

A whole-virus H1N1 A/California/07/2009 vaccine was safe and well tolerated and a single dose induced substantial immune responses similar to seasonal influenza vaccines, probably due to immunological priming by previous seasonal influenza vaccines or infections.