The effect of anti-tumour necrosis factor alpha treatment on the antibody response to influenza vaccination.

OBJECTIVES: The effect of anti-tumour necrosis factor (TNF) therapy on the antibody responses to vaccines is the subject of ongoing debate. Therefore, we investigated the effect of the three currently available anti-TNF agents on influenza vaccination outcomes in a patient population with long-standing disease. METHODS: In a prospective cohort study, we assessed the antibody response upon influenza vaccination in 112 patients with long-standing autoimmune disease treated with immunosuppressive medication either with anti-TNF (etanercept, adalimumab or infliximab; n = 64) or without anti-TNF (n = 48) and a control group of 18 healthy individuals. Antibody responses were determined by haemagglutination inhibition assay, before and 4 weeks after vaccination. RESULTS: The proportion of individuals with a protective titre (>or=40) after vaccination was large (80-94%) and did not significantly differ between the three groups. Post-vaccination geometric mean antibody titres against influenza (A/H3N2 and B) were significantly lower in the 64 patients treated with anti-TNF compared with the 48 patients not receiving anti-TNF, and the healthy controls. CONCLUSIONS: The antibody response to influenza vaccination in patients treated with anti-TNF is only modestly impaired. The proportion of patients that achieves a protective titre is not significantly diminished by the use of TNF blocking therapies.

Humoral immune response to influenza vaccination in patients with primary immunoglobulin A nephropathy. An analysis of isotype distribution and size of the influenza-specific antibodies.

Primary IgA nephropathy (IgAN) is characterized by mesangial deposits of IgA1, increased serum IgA1 levels, and circulating immune complexes containing predominantly IgA1. It has previously been found that patients with IgAN have a higher than normal IgA response to vaccination, but the IgA subclasses have not been studied. To investigate whether the IgA hyperresponsiveness is limited to the subclass IgA1, which is involved in the pathogenesis of IgAN, we compared the immune responses of 18 patients with 22 healthy controls after intramuscular vaccination with inactivated influenza virus. Antibody titers were significantly higher (P less than 0.0001) for the IgA1 subclass in patients versus controls, but not for the other isotypes. A substantial portion of the IgA and IgA1 antiinfluenza immune response comprised polymers in both patients and controls. There was no preferential response of polymers in patients. Patients produced significantly more monomeric IgA1 antibodies than controls. These results show that patients with IgAN have a hyperresponsiveness limited to the subclass IgA1 and mainly expressed by an excess of monomers.

Rationale for two influenza B lineages in seasonal vaccines: A meta-regression study on immunogenicity and controlled field trials.

B lineage mismatch prompted introduction of quadri-valent influenza vaccines (QIV) with two influenza B viruses representing distinct antigenic lineages. To explore the impact on antibody induction and vaccine effectiveness predicted from antibody (VEab), we performed a systematic literature search on immunogenicity studies conducted to assess antibody superiority of QIV over trivalent influenza vaccine (TIV). Thirteen relevant articles described 31 trials from 2007 and 2013. Log-transformed GMT trial estimates and their variances were converted to clinical protection rates predicted from antibody (PRab). VEab estimates were calculated from pre- and post-vaccination PRab. Without specific pre-vaccination immunity, average VEab was 69% for match, and -4% for lineage mismatch. With increasing pre-vaccination seropositivity, mismatch impact declined to 2%. We also performed an umbrella literature search for randomised controlled trials and test-negative case-control trials with TIV, and estimated vaccine effectiveness against laboratory-confirmed influenza B (VEf). Sixty-eight eligible clinical articles described 110 season-trials from 1965 to 2012, covering seasons with B lineage match (n=52), lineage drift (n=15) and lineage mismatch (n=43). With no pre-vaccination antibody levels determined, we used chance of previous exposure to influenza B (Ppe) as pre-seasonal immunity measure. When Ppe was 0%, average VEf for matched seasons was 67%, and for mismatched seasons 35%, indicating a moderate, yet significant mismatch impact on VEf. With increasing Ppe, mismatch impact declined to 3%. Thus serological and field trials indicate that B lineage mismatch impact is negatively related to pre-seasonal immunity and that the gain of QIV over TIV most benefits infants and children not yet exposed to influenza B.

Protection against influenza after annually repeated vaccination: a meta-analysis of serologic and field studies.

BACKGROUND: According to common recommendations, influenza vaccination should be performed annually. It has been suggested that vaccination in previous years reduces vaccine efficacy in the long term. OBJECTIVE: To determine whether the protection of influenza vaccine decreases when vaccination is repeated annually. METHODS: Articles published between 1966 and 1997 were selected from MEDLINE. The end point for field studies was the influenza-related morbidity or mortality during influenza outbreaks (resulting in field protection rates). The end point for serologic studies was exceeding a protective postvaccination hemagglutination-inhibition titer (serologic protection rates). Protection rate differences between groups with single and multiple vaccinations were subjected to meta-analysis. RESULTS: Seven field studies (including 13 trials) supported the hypothesis that protection in multiple-vaccination groups is at least as good as that in single-vaccination groups. Ten trials with 5117 observations could be subjected to meta-analysis. The pooled protection-rate difference was close to 0 (1.1%; 95% confidence interval, -0.2% to 2.4%), thus detecting no difference between single or multiple vaccination. Twelve serologic studies (including 53 trials) showed heterogeneous results: 9 trials were significantly in favor of single vaccination, and 7 were in favor of multiple vaccination, but in most cases, there was no significant difference between the 2 vaccination groups. The pooled serologic protection-rate difference from 52 trials (12341 observations) was again close to 0 (1.7%; 95% confidence interval, -1.3% to 4.8%). CONCLUSIONS: We did not detect any evidence for a decreasing protection with annually repeated influenza vaccination. Annual vaccination should not be discouraged in populations at risk.

Impairment of the immune response to influenza vaccination in renal transplant recipients by cyclosporine, but not azathioprine.

Influenza vaccination has been strongly recommended for immunosuppressed renal transplant recipients. However, immunosuppression may lead to impaired antibody responses. We studied the antibody response to an inactivated trivalent influenza vaccine in 59 renal transplant recipients with life-sustaining kidney function: 21 were on cyclosporine and prednisone, 38 on azathioprine and prednisone. Healthy volunteers (n = 29) and patients on hemodialysis (n = 28) served as controls. Despite comparable renal allograft function, cyclosporine-treated patients had a significantly lower immune response against influenza A viruses than azathioprine-treated patients, whether mean antibody levels, fourfold titer rise, or seroconversion to protective titers was analyzed. No significant differences in antibody responses were found between healthy controls and patients on azathioprine. The patients on hemodialysis showed an impaired response to vaccination. However, in contrast to the cyclosporine-treated patients, booster immunization proved valuable in this group.

Seroprotection rate, mean fold increase, seroconversion rate: which parameter adequately expresses seroresponse to influenza vaccination?

Serological parameters intend to describe antibody response to influenza vaccine in a population. However, there is uncertainty about the mathematical appropriateness and the biological or clinical meaning of conventionally used parameters. Theoretical considerations and exploration of a data-set of 16 studies with an inactivated (subunit) influenza vaccine involving 1176 adult subjects suggest the following conclusions. In a population seronegative before vaccination, the post-vaccination geometric mean titre (post-GMT) is a meaningful immunological parameter adequately expressing antibody response after vaccination. The related protection rate (PR) is a good surrogate parameter for protection provided by a given vaccine, thus relevant to public health. However, in a population partially seropositive before vaccination (due to previous exposition to influenza antigens), the same parameters may, under certain conditions, seriously overestimate the antibody response, as they do not account for the pre-vaccination state. Conventional attempts to address pre-vaccination antibody are associated with either loss of information (exclusion of seropositive subjects) or incomplete control of pre-vaccination state (mean fold increase (MFI), response rate (RR)). Although not devoid of theoretical limitations (heteroscedasticity), correction of post-GMT and PR by linear regression appears to provide better estimates of antibody response and vaccine immunogenicity.

Influenza: relation of mortality to morbidity parameters--Netherlands, 1970-1989.

The purpose of this study is to investigate the relationship between the number of influenza-like illness (ILI), weekly registered by the general practitioners (sentinel stations), and the monthly overall influenza mortality in people over 60 years of age, provided by the Dutch Statistical Bureau during the period July 1970 to June 1989. The quantitative impact of influenza-morbidity is expressed by three summary parameters, calculated from the 52 (53) weekly ILI-figures per season-year, (i) their sum (i.e. global extent of an epidemic), (ii) their standard deviation, and (iii) their maximum (i.e. peak number of ILI during an epidemic). In the analysis influenza A subtype is also included. These four parameters are mutually compared with respect to their predictability for yearly total influenza mortality in the 19 season-years available. In most cases, the standard deviation and the peak number of ILI are more powerful for prediction of mortality, than the global extent of the epidemic. The peak number of ILI is of special interest. It is particularly useful for estimating the effect on current influenza mortality during an ongoing epidemic. From the model it is possible to calculate a threshold (of weekly ILI) beyond which mortality increases proportionately more than the number of illness episodes. By using the peak value of morbidity it is possible to calculate the minimal impact of epidemic mortality. This study indicates that the weekly number of influenza-like illnesses has a certain prognostic value for the real impact of influenza. An electronic surveillance system could detect immediately the threshold above which influenza mortality increases more than proportionally.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of influenza on mortality in relation to age and underlying disease, 1967-1989.

Based on data from the Dutch Central Bureau of Statistics, the impact of influenza on mortality in The Netherlands was estimated for a 22.5-year period (1967-1989) in four age groups and three entities of disease, using Poisson regression techniques. Our analysis suggests that, on average, more than 2000 people died from influenza in The Netherlands each year, but in only a fraction of these deaths was influenza recognized as the cause of death. For each case of death registered as caused by influenza (registered influenza mortality), 2.6 additional cases of death registered as due to causes other than influenza, nevertheless, were influenza-related (non-registered influenza mortality). Therefore, the overall impact of influenza on mortality is estimated to be greater than registered influenza mortality by a factor of 3.6. Those under 60 years of age accounted for 5% of all non-registered influenza deaths, whereas people aged 60-69, 70-79 years and > 80 years accounted for 12%, 29% and 54% of such deaths, respectively. When extrapolating the figures for the Dutch population of 1989, we could attribute, on average per season-year, 82 deaths per 100,000 people > 60 years, 143 in people > 70 years, and 280 in people > 80 years. Of all non-registered influenza cases of death, 47% were estimated to occur in people with heart disease as a primarily reported cause of death, 23% in those with lung disease, and 30% in those with other diseases. This study stresses the serious effects of influenza, mainly in the elderly (95% of non-registered influenza mortality).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of antigenic relationships among influenza virus strains using a taxonomic cluster procedure. Comparison of three kinds of antibody preparations.

Hemagglutination inhibiting (HI) monoclonal antibody preparations (MA) were raised against six influenza A (H3N2) strains from the period 1977-1982. Twenty-three hybridomas were selected and titrated in HI assays against these strains and against 18 influenza A (H3N2) viruses isolated in The Netherlands during the seasons 1981-1982 and 1982-1983. Similar HI tests were performed with conventional post-infection ferret antisera and with ferret antisera adsorbed with heterologous strains of influenza A (H3N2) virus. The resulting serological data were subjected to a computerized taxonomic cluster procedure based on the Euclidean distance between viruses. With respect to the degree of separation between clusters the unadsorbed ferret antisera were inferior to the adsorbed antisera whereas the MA were superior to both. Our results demonstrate that computer programs based on numerical taxonomy can be helpful in processing large numbers of serological data and that MA are indispensable in epidemiological and diagnostic influenza studies.

Haemagglutination-inhibiting antibody to influenza virus.

The results of the haemagglutination-inhibiting (HI) antibody test for influenza virus antibody in human sera closely match those produced by virus neutralization assays and are predictive of protection. On the basis of the data derived from 12 publications concerning healthy adults, we estimated the median HI titre protecting 50% of the vaccinees against the virus concerned at 28. This finding supports the current policy requiring vaccines to induce serum HI titres of > or = 40 to the vaccine viruses in the majority of the vaccinees. Unfortunately similar studies are scanty for the elderly, the group most at risk of influenza. There still remain many unsolved technical problems with the HI assay and we recommend that these problems be studied and the virus neutralization test as a predictor of resistance to influenza be assessed. Although the studies on this issue often give conflicting results, they generally show that HI antibody responses to influenza vaccination tend to diminish with increasing age, when health is often compromized. Advanced age in itself seems not to be an independent factor in this process. However, even in completely healthy elderly individuals the response to vaccination with an antigenically new virus may be strongly reduced compared with younger vaccinees.

Comparison of Serology and Reactogenicity between Influenza Subunit Vaccines and Whole Virus or Split Vaccines: A Review and Meta-Analysis of the Literature.

Currently three different inactivated influenza vaccine types are available: whole virus (WV), split (SPL) and subunit (SU) vaccines. Physicians and patients at risk for influenza complications may wonder whether there are important differences between the vaccine types with respect to antibody induction (serology) and adverse effects (reactogenicity). A literature review (1975 to 1995) was performed to evaluate the serology and reactogenicity of SU vaccines in comparison with either split or whole virus vaccines. 22 publications with randomised allocation were identified describing a total of 5416 serological observations, 2858 observations of local reactions, and 2990 observations of systemic reactions. Subjects included those from all age groups from children to the elderly. Absolute protection and reaction rate differences (RD) were calculated for the comparisons SU vs SPL or SU vs WV vaccine. These were subjected to a method of meta-analysis, resulting in pooled rate differences and their 95% confidence intervals. With the exception of the comparison SU vs WV vaccine in subjects born after 1957 and unexposed to the reappearing H1N1 subtype after 1977, no evidence was found to suggest relevant differences in seroresponse among the three currently available inactivated influenza vaccine types. Although insufficient data were available in the meta-analysis for vaccines in children for whom specific recommendations concerning these vaccines exist, adverse events after administration of any of the three vaccine types were generally mild and transitory; however, SU vaccines were associated with a lower frequency of local and systemic reactions.

[Influenza epidemic in a nursing home caused by a virus not included in the vaccine]. / Influenza-epidemie in een verpleeghuis door een virus dat niet in het vaccin was opgenomen.

In the autumn of 1992 two-thirds of the population of a nursing home in Amsterdam was vaccinated against influenza. However, in March 1993 an outbreak of an influenza like illness occurred with a morbidity rate of 49% and a mortality rate of 10%. There was sufficient serological evidence to show that the vaccine as such had induced adequate immunity. As the causative agent an influenza A/H3N2 virus was identified. The failing activity of the vaccine in this instance was apparently caused by the absence of sufficient antigen similarity between the A/H3N2 vaccine component and the epidemic virus ('vaccine mismatch').

[Neuraminidase inhibitors oseltamivir and zanamivir: new means of defence against influenza]. / De neuraminidaseremmers oseltamivir en zanamivir: een nieuw schild in de verdediging tegen influenza.

Recently two new neuraminidase inhibitors zanamivir and oseltamivir have been marketed. They appear to considerably reduce morbidity and mortality from influenza. Their adverse effects are infrequent and mild and the chance of development of pathogenically significant resistant mutants appears to be small. During the first six months of a pandemic, neuraminidase inhibitors are the only defence against the virus. It is therefore important to stockpile in each country sufficient quantities of these drugs. During the usual influenza epidemics the main value of neuraminidase inhibitors lies in their use for therapy, prophylaxis and post-exposure prophylaxis in long-term care institutions for the elderly (for prophylaxis only oseltamivir is licensed). Although data on the effectiveness against complications of influenza and on the effect on people with an increased risk of (fatal) complications as a result of an influenza virus infection are limited, the available information on the effects of the neuraminidinase inhibitors indicates that these drugs will also protect against complications and that high-risk groups will benefit from the rapid deployment of these products. The cost-effectiveness of treatment and post-exposure prophylaxis with neuraminidinase inhibitors is probably not favourable for healthy children and adults but seems to be favourable for the high-risk groups (vaccinated or not) in winter.

Antibody landscapes after influenza virus infection or vaccination.

We introduce the antibody landscape, a method for the quantitative analysis of antibody-mediated immunity to antigenically variable pathogens, achieved by accounting for antigenic variation among pathogen strains. We generated antibody landscapes to study immune profiles covering 43 years of influenza A/H3N2 virus evolution for 69 individuals monitored for infection over 6 years and for 225 individuals pre- and postvaccination. Upon infection and vaccination, titers increased broadly, including previously encountered viruses far beyond the extent of cross-reactivity observed after a primary infection. We explored implications for vaccination and found that the use of an antigenically advanced virus had the dual benefit of inducing antibodies against both advanced and previous antigenic clusters. These results indicate that preemptive vaccine updates may improve influenza vaccine efficacy in previously exposed individuals.

Immunogenicity and safety of inactivated influenza vaccines in primed populations: a systematic literature review and meta-analysis.

Several inactivated influenza vaccine formulations for systemic administration in man are currently available for annual (seasonal) immunization: split virus and subunit (either plain-aqueous, or virosomal, or adjuvanted by MF59). From a literature search covering the period 1978-2009, 33 articles could be identified, which described randomized clinical trials comparing at least two of the four vaccine formulations with respect to serum hemagglutination inhibition (HI) antibody response, local and systemic vaccine reactions and serious adverse events after vaccination, and employing seasonal vaccine components and doses. In total, 9121 vaccinees of all ages, either healthy or with underlying diseases, were involved. Most vaccinees were primed or had been vaccinated in previous years. For immunogenicity, homologous post-vaccination geometric mean HI titers (GMTs) were analyzed by a random effects model for continuous data. Unreported standard deviations (SD) were addressed by imputing assumed SD-values. Age and health state of the vaccinees appeared to have little influence on the outcome. The immunogenicity of split, aqueous and virosomal subunit formulations were similar, with geometric mean ratio values (GMR, quotient of paired GMT-values) varying around one (0.93-1.24). The MF59-adjuvanted subunit vaccine induced, on average, larger antibody titers than the non-adjuvanted vaccine formulations, but the absolute increase was small (GMR-values varying between 1.25 and 1.40). Vaccine reactions were analyzed using a random effects model for binary data. Local and systemic reactogenicity was similar among non-adjuvanted formulations. The adjuvanted subunit formulation was more frequently associated with local reactions than the non-adjuvanted formulations (rate ratio: 2.12, significant). Systemic reactions were similar among all vaccine formulations. The original articles emphasized the mild and transient character of the vaccine reactions and the absence of serious vaccine-related adverse events. This adequate amount of evidence led to the conclusion that all the currently available inactivated influenza vaccine formulations are safe, well tolerated and similarly effective to control seasonal influenza outbreaks across primed populations and age ranges.