Accounting for vaccines specificities in the Joint Clinical Assessment (JCA): a proposal for guiding principles

Issue/problem

Vaccines are an important public health intervention protecting the population against infectious diseases. The value of vaccines is broad ranging from individual to societal as achieving community immunity protects the unvaccinated, minimizes the risk of outbreaks, reduces the emergence of antimicrobial resistance, and leads to broader societal benefits.

Description of the problem

Vaccines’ market access processes are characterized by the development of recommendations by NITAGs followed by the assessment of health technology assessment (HTA) bodies in less than half of 27 EU member states. Despite that HTA for therapeutic drugs is well established, there is very limited experience in applying HTA methodologies to vaccines, especially for clinical assessments, as HTA methods and frameworks are traditionally geared toward therapeutics. However, following the adoption of the EU regulation on HTA, Joint Clinical Assessments (JCAs) of vaccines are expected.

Results

To support a discussion on how to account for vaccine specificities in the JCA, Vaccines Europe has performed a project which aimed at developing a proposal for high-level guiding principles on processes and methodologies for clinical HTA for vaccines. The proposal is informed by findings of literature reviews on currently applied processes, methods, and clinical assessment frameworks of vaccines as well as the outcomes of an advisory board with scientific experts.

Lessons

A proposal for high-level guiding principles for clinical HTA for vaccines is being developed based on both evidence and the advice from scientific experts which focuses on processes (e.g., horizon scanning, early advice, consideration of vaccine-specific expertise) and methods (e.g., unmet need, safety, efficacy/effectiveness, real-world evidence and technical characteristics of the technology). Lastly, the implementation of vaccines specificities in JCA represents a call for action.

Invasion by Bactrocera dorsalis and niche partitioning among tephritid species in Comoros

Ten economically important species belonging to the Tephritidae have been recorded in Union of the Comoros (an island nation off the coast of East Africa). Little is known about the distribution of these species and how they are affected by climatic factors in the Comoros archipelago. The main objectives of this study were to characterize: (i) the population dynamics of tephritid fruit flies in relation to season and host fruit availability and (ii) the geographic distribution of tephritids in relation to temperature and rainfall. The study was conducted during 2 years at 11 sites on three islands (Grande Comore, Anjouan, and Mohéli) in the archipelago. The site elevations ranged from 55 to 885 m a.s.l. At each site, flies were collected weekly in eight traps (four different lures, each replicated twice). Fruit phenology was also recorded weekly. The dominant tephritid species detected was the invasive Bactrocera dorsalis Hendel followed by Ceratitis capitata Wiedemann. Tephritid species were generally more abundant during the hot and rainy seasons than during the cold and dry seasons. Bactrocera dorsalis numbers were higher on Grande Comore than on the two other islands. On Anjouan and Mohéli, B. dorsalis numbers were very low in 2014 but sharply increased in 2015, suggesting a recent invasion of these islands. Abundances were significantly related to the fruiting of mango, strawberry guava, and guava for B. dorsalis and to the fruiting of mango, guava, and mandarin for C. capitata. Bactrocera dorsalis was more abundant in hot and humid low-altitude areas, while C. capitata was more abundant in dry medium-altitude areas, suggesting the occurrence of climatic niche partitioning between the two species.

Cryptic diversity and gene flow among three African agricultural pests: Ceratitis rosa, Ceratitis fasciventris and Ceratitis anonae (Diptera, Tephritidae)

The 'Ceratitis FAR complex' is a species complex of African fruit flies (Diptera, Tephritidae) including the major agricultural pest Ceratitis rosa and the morphologically similar Ceratitis fasciventris and Ceratitis anonae. To resolve their intra- and interspecific genetic relationships and to estimate gene flow within this complex, we surveyed allelic variation at 16 microsatellite loci in 27 African populations of the three morphospecies. Interpopulation genetic distances and individual Bayesian assignments distinguished five genotypic clusters: two involving C. rosa (R1, R2; that may occur in sympatry), two involving C. fasciventris (F1, F2; with parapatric distributions) and one involving C. anonae (A). Intra- and interspecific patterns of genetic differentiation were not hierarchically structured and genetic differentiation between conspecific clusters (F1-F2 and R1-R2) was higher or comparable with differentiation between heterospecific clusters (e.g. F1-A or R2-A). In some cases, gene flow estimates among morphospecies or among heterospecific genotypic clusters were significantly different from zero, showing the lack of reproductive isolation. Genetic differentiation between genotypic clusters was partly supported by morphological differences observed a posteriori in male secondary sexual characters. These results suggest important revisions to current models of ecological niche requirements and invasion risk of the major agricultural pest C. rosa and provide a basis for a taxonomic re-interpretation of the FAR complex.

Species diversity within a community of the curcurbit fruit flies Bactrocera cucurbitae, Dacus ciliatus, and Dacus demmerezi roosting in corn borders near cucurbit production areas of Reunion Island

In order to better control fruit flies (Diptera: Tephritidae) attacking Cucurbitaceae on Reunion Island (21°6 S/ 55°36 E), biological characteristics (seasonal fluctuation, relative abundance, sex ratio) of communities roosting in corn borders were investigated. The study was conducted in austral summer across a range of altitudes (750-1150 m) corresponding to the main areas of cucurbit cropping. Living adults were recorded roosting on corn planted within or around cucurbit fields. Results showed a high variability in seasonal fluctuation of populations according to local conditions. Bactrocera Cucurbitae (Coquillett) (Diptera: Tephritidae) was the least abundant species (27%) compared to Dacus ciliatus Loew (36%) and Dacus demmerezi Bezzi (37%). Relative abundance of B. Cucurbitae was lowest (< 18%) in high altitude sites (above 1000 m), where D. demmerezi was the most prevalent species (> 56%). Dacus ciliatus showed variable relative abundance (from 18 to 51%) depending on the experimental design (varying in location and in year). Sex ratio was also very variable from one species to another and from one experimental design to another.

Biotic and abiotic factors affecting the flight activity of Fopius arisanus, an egg-pupal parasitoid of fruit fly pests

Climatic conditions and the physiological state of a parasitoid may alter its host selection behavior and thus its efficiency as a biological control agent. We studied the influence of these parameters on the behavior of Fopius arisanus (Sonan), an egg-pupal parasitoid of many Tephritidae. In the first experiment, we assessed in field cage assays the influence of temperature, humidity, light intensity, barometric pressure, and wind speed. Both flight and parasitism were mainly affected by temperature and humidity. However, because these two factors were strongly correlated in our experiments, the direct influence of each one cannot be specified. Flight activity was affected by variations in barometric pressure. In a second set of experiments, we conducted release and recapture assays with dyed insects to determine the influence of sex, mating status, egg load, age, and starvation on attraction toward infested fruit. Males were not attracted, suggesting that fruit are not a mating site. The egg load seemed to be a major parameter of foraging motivation. Finally, we showed that flight activity strongly decreased after 48 h of starvation. We observed a possible switch to food in the foraging motivation of starved females, but this result was impaired by poor recoveries: <10% of released females were recaptured after 96 h of starvation. We finally discuss the importance of these observations on the efficiency of F. arisanus as a biological control agent in tropical humid areas.

Influence of habitat pattern on orientation during host fruit location in the tomato fruit fly, Neoceratitis cyanescens

Fruit flies have evolved mechanisms using olfactory and visual signals to find and recognize suitable host plants. The objective of the present study was to determine how habitat patterns may assist fruit flies in locating host plants and fruit. The tomato fruit fly, Neoceratitis cyanescens (Bezzi), was chosen as an example of a specialized fruit fly, attacking plants of the Solanaceae family. A series of experiments was conducted in an outdoor field cage wherein flies were released and captured on sticky orange and yellow spheres displayed in pairs within or above potted host or non-host plants. Bright orange spheres mimicking host fruit were significantly more attractive than yellow spheres only when placed within the canopy of host plants and not when either within non-host plants or above both types of plants. Additional experiments combining sets of host and non-host plants in the same cage, or spraying leaf extract of host plant (bug weed) on non-host plants showed that volatile cues emitted by the foliage of host plants may influence the visual response of flies in attracting mature females engaged in a searching behaviour for a laying site and in assisting them to find the host fruit. Moreover, the response was specific to mature females with a high oviposition drive because starved mature females, immature females and males showed no significant preference for orange spheres. Olfactory signals emitted by the host foliage could be an indicator of an appropriate habitat, leading flies to engage in searching for a visual image.

A cost-effectiveness analysis of n-3 PUFA (Omacor) treatment in post-MI patients

This study evaluates the cost-effectiveness of Omacor treatment as a standard prevention measure post-MI in the UK. A cost-effectiveness model was developed based on the GISSI-P trial, combining a survival and a Markov model, over a lifetime period. The base case results for Omacor, at 4 years and over a lifetime, respectively, were: cost [corrected] per QALY gained: pound15,189 and 3,723; [corrected] cost per life years gained (LYG): pound12,011 and pound2,812 [corrected] The cost per death avoided at 4 years was pound31,786. Deterministic and probabilistic sensitivity analyses did not change the base case results substantially. The use of Omacor as a standard post-MI prevention treatment seems warranted in the UK, both on the basis of its efficacy, which is in addition to other prophylactic treatments as evidenced by the results of the GISSI-P trial, and on cost-effectiveness grounds - both at 4 years and over a lifetime's time-horizon, using the current cost-effectiveness thresholds.

Cost-effectiveness of acarbose for the management of impaired glucose tolerance in Sweden

We assessed the cost-effectiveness of acarbose in the management of patients with impaired glucose tolerance (IGT) in Sweden, based on progression to type 2 diabetes (T2D) and cardiovascular (CV) events reported in the STOP-NIDDM trial population, including high-risk subgroups. The cost per patient free from T2D was SEK28,000 or SEK1260 per diabetes free month prior to progression to T2D. The cost per patient free from CV events was SEK101,000 or SEK5000 per CV event free month. For the high CV risk subgroups, acarbose treatment dominated placebo (i.e. acarbose was more effective, less costly). Acarbose significantly reduces the incidence of diabetes and CV events in IGT patients. We predict this may translate into healthcare cost savings that partially or, in patients at high CV risk, fully offset the cost of acarbose. We conclude that acarbose is likely to be cost-effective in the management of impaired glucose tolerance.

Influence of adding borax and modifying pH on effectiveness of food attractants for melon fly (Diptera: Tephritidae)

The melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae), is the most damaging pest of cucurbits in Reunion Island. The influence of adding borax and modifying pH on the effectiveness of different food attractants for both sexes of the melon fly is analyzed by a release-recapture method in field cages. Adding borax to protein hydrolysates Nulure and Buminal strongly reduced their attractiveness for B. cucurbitae. Acidification of 5% Buminal solution (from pH 6 to pH 3) doubled its attractiveness for melon fly. Conversely, Torula yeast at pH 10.5 was significantly more attractive than the standard Torula yeast at pH 9 (28% of captured flies compared with 17%). However, a further pH increase of the yeast solution does not improve its attractiveness. The results are discussed in relation to other studies on pH modification of various baits for Tephritidae.

Population genetics of the potentially invasive African fruit fly species, Ceratitis rosa and Ceratitis fasciventris (Diptera: Tephritidae)

A set of 10 microsatellite markers was used to survey the levels of genetic variability and to analyse the genetic aspects of the population dynamics of two potentially invasive pest fruit fly species, Ceratitis rosa and C. fasciventris, in Africa. The loci were derived from the closely related species, C. capitata. The degree of microsatellite polymorphism in C. rosa and C. fasciventris was extensive and comparable to that of C. capitata. In C. rosa, the evolution of microsatellite polymorphism in its distribution area reflects the colonization history of this species. The mainland populations are more polymorphic than the island populations. Low levels of differentiation were found within the Africa mainland area, while greater levels of differentiation affect the islands. Ceratitis fasciventris is a central-east African species. The microsatellite data over the Uganda/Kenya spatial scale suggest a recent expansion and possibly continuing gene flow within this area. The microsatellite variability data from C. rosa and C. fasciventris, together with those of C. capitata, support the hypothesis of an east African origin of the Ceratitis spp.

The ceratotoxin gene family in the medfly Ceratitis capitata and the Natal fruit fly Ceratitis rosa (Diptera: Tephritidae)

Ceratotoxins (Ctxs) are a family of antibacterial sex-specific peptides expressed in the female reproductive accessory glands of the Mediterranean fruit fly Ceratitis capitata. As a first step in the study of molecular evolution of Ctx genes in Ceratitis, partial genomic sequences encoding four distinct Ctx precursors have been determined. In addition, anti-Escherichia coli activity very similar to that of the accessory gland secretion from C. capitata was found in the accessory gland secretion from Ceratitis (Pterandrus) rosa. SDS-PAGE analysis of the female reproductive accessory glands from C. rosa showed a band with a molecular mass (3 kDa) compatible with that of Ctx peptides, also slightly reacting with an anti-Ctx serum. Four nucleotide sequences encoding Ctx-like precursors in C. rosa were determined. Sequence and phylogenetic analyses show that Ctxs from C. rosa fall into different groups as C. capitata Ctxs. Our results suggest that the evolution of the ceratotoxin gene family might be viewed as a combination of duplication events that occurred prior to and following the split between C. capitata and C. rosa. Genomic hybridization demonstrated the presence of multiple Ctx-like sequences in C. rosa, but low-stringency Southern blot analyses failed to recover members of this gene family in other tephritid flies.

Comparison of the efficacy of different food attractants and their concentration for melon fly (Diptera: Tephritidae)

The relative attractiveness of six commercially available protein hydrolysates and the influence of their concentration were evaluated in field cages by a release-capture method of lab-reared melon fly adults, Bactrocera cucurbitae (Coquillett). Buminal, Corn Steepwater, Hym-Lure, Pinnacle, Nulure, and SolBait were tested for both sexes of the melon fly. The tested products exhibited clear differences in attractiveness. SolBait was the most effective protein hydrolysate. Pinnacle and Corn Steepwater also gave promising results. A general tendency for an increase in effectiveness with increasing concentration within the range 0.5 to 10% was shown. This study will allow pest control practitioners to choose more effective attractants for use in bait sprays to control the melon fly thus reducing the intensive use of insecticides currently practiced in Reunion island and enabling the development of Integrated pest management (IPM) methods for cucurbit crops.

Survival and development of different life stages of three Ceratitis spp. (Diptera: Tephritidae) reared at five constant temperatures

Fruit flies (Diptera: Tephritidae) are the most damaging pests on fruit crops on Réunion Island, near Madagascar. Survival and development of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), the Natal fruit fly, C. rosa Karsch and the Mascarenes fruit fly, C. catoirii Guérin-Mèneville were compared at five constant temperatures spanning 15 to 35 degrees C. Durations of the immature stages of C. capitata, C. rosa and C. catoirii ranged from 14.5-63.8, 18.8-65.7 and 16.8-65.8 days, respectively, at 30-15 degrees C. The lower developmental threshold and thermal constant were calculated using the temperature summation model. The thermal constant for total development of the immature stages of C. capitata, C. rosa and C. catoirii were 260, 405 and 356 DD, respectively. Species differed mainly during the larval stages and ovarian maturation period, with smaller differences in the egg stage. Ceratitis rosa appeared to be better adapted to low temperatures than the two other species as it showed a lower larval developmental threshold of 3.1 degrees C compared to 10.2 degrees C for C. capitata and 8.9 degrees C for C. catoirii. Overall, C. catoirii had a low survival rate within the range of temperatures studied. The different responses of the three Ceratitis species to various temperatures explain to some extent their distribution on the island. The results obtained will be used for optimizing laboratory rearing procedures and for constructing computer simulation models to predict fruit fly population dynamics.

Blood levels of total homocysteine in patients with type 1 diabetes (with no complications, diabetic nephropathy and/or retinopathy) and in their non-diabetic relatives

BACKGROUND AND AIM

It has been reported that plasma homocysteine (Hcy) levels in type 1 diabetes (T1DM) patients without renal involvement are higher, similar to or lower than those in healthy controls.

METHODS AND RESULTS

We measured plasma Hcy in 60 controls, 79 type 1 diabetics (23 with retinopathy, 22 with nephropathy) and 73 non-diabetic relatives of 30 probands. The female controls had lower levels than their male counterparts: geometric mean 10.5 vs 13.6 mumol/L, p < 0.001. Among the controls, smokers (n = 20) and ex-smokers (n = 12) had higher Hcy levels than non-smokers (n = 28): 13.2 and 13.2 vs 10.9 mumol/L, p < 0.01. Among the diabetics, high plasma Hcy levels were associated with male gender: 11.9 vs 9.1 mumol/L in women, p < 0.01. The patients without complications had higher plasma glucose and hemoglobin A1c (HbA1c) levels (p < 0.001), and lower plasma Hcy (9.2 mumol/L vs 12.2, p < 0.01) and uric acid levels (p < 0.05) than the controls. The patients with nephropathy and higher levels of Hcy (13.0 mumol/L vs 9.0, p < 0.05), and different levels of creatinine (p < 0.01), uric acid (p < 0.01), fibrinogen (p < 0.05), and urinary albumin (p < 0.001) than those with retinopathy. There was no difference in Hcy levels between the patients' relatives and the controls: 11.9 mumol/L in siblings vs 11.6 mumol/L, 13.5 mumol/L in parents vs 12.1 mumol/L. In the control group, plasma Hcy levels were associated with age, gender and smoking; among the diabetics, they correlated with age, gender, smoking, and plasma creatinine and lipoprotein (a) levels.

CONCLUSIONS

1) male gender and smoking are associated with high Hcy levels in healthy people; 2) plasma Hcy levels are lower in T1DM patients than in healthy people (glomerular hyperfiltration and accelerated hepatic transsulfuration?); 3) high Hcy levels are associated with diabetic nephropathy and plasma creatinine levels; and 4) non-diabetic first-degree relatives of type 1 diabetics have normal plasma Hcy concentrations.

Screening for coeliac disease in families of adults with Type 1 diabetes based on serological markers

The prevalence of coeliac disease (CD) in the adult population is unknown because silent and latent stages do exist. Type 1 diabetes mellitus may be associated with CD because of common genetic background and/or shared pathogenetic mechanisms. We investigated 74 adults with type 1 diabetes (32+/-11 yr, disease duration 13+/-9 yr), 69 parents of diabetic probands (56+/-10 yr), 59 siblings (30+/-11 yr) and 50 healthy controls (35+/-10 yr) for the presence of circulating islet cell antibodies (ICA), anti-glutamic acid decarboxylase antibodies (GADA65), anti-gliadin immunoglobulins A and G (IgA- and IgG-AGA). All patients with raised AGA, performed also IgA anti-endomysium antibody (EmA) indirect immunofluorescence assay. Samples were positive for ICA in 19 diabetics (26%), 4 parents (6%), 4 siblings (7%), 0 controls (p<0.001); for GADA in 34 diabetics (46%), 4 parents (6%), 1 sibling (2%), 0 controls (p<0.001). Twenty-five diabetic patients (34%), 10 parents (14%), 5 siblings (8%), 3 controls (6%) (p<0.001) had raised IgA-AGA (>4.4 mg/l). Four diabetic patients (5%), 5 parents (7%), 0 siblings (0%), 4 controls (8%) had raised IgG-AGA (>18 mg/l). Both IgA- and IgG-AGA were detected in 1 diabetic and 2 parents. The prevalence of ICA, GADA, and IgA-AGA positivity in Type 1 diabetes patients was significantly higher than in controls (p<0.001). Finally, 50 AGA-positive subjects performed EmA test: only 2 of them resulted EmA-positive, a diabetic patient and a sibling. The patient with Type 1 diabetes had a small-bowel biopsy specimen consistent with CD and, as sole evidence of malabsorption, sideropenic anaemia. EmA-positive sibling also showed severe iron deficiency, yet refused endoscopy. We conclude that: 1) CD cannot be diagnosed on the basis of associated IgA- and IgG-AGA alone. Nevertheless, detection of such antibodies is useful, in combination with EmA, in screening for endoscopic biopsy; 2) too high rate of detection of IgA-AGA in Type 1 diabetic patients in comparison with other groups excludes a false positivity of the test itself, while suggests a pathogenetic association of both immunological disorders, perhaps related to abnormal gammadelta TCR-bearing intraepithelial lymphocytes.