SCIENTIFIC DISCUSSION

Product Name: Birnagen Forte As Emulsion MA Holder: Novartis Animal Vaccines Ltd

for Injection for Atlantic Salmon

I. introduction

Birnagen Forte As Emulsion for Injection for Atlantic Salmon is indicated for active immunisation against Infectious Pancreatic Necrosis virus and Aeromonas salmonicida to reduce Infectious Pancreatic Necrosis Virus (IPNV) and furunculosis related mortality of Atlantic salmon (Salmo salar) populations.

The bacterial component is present in a currently authorised product for use in the treatment of furunculosis. The formulation of this product is identical to that of Birnagen Forte As Emulsion for Injection for Atlantic Salmon with the exception of the addition of the IPNV component.

Data provided supports a Provisional Marketing Authorisation. For a provisional authorisation, the company must demonstrate that the quality of the product is adequate, that the major safety questions have been answered and that there is some evidence that the product will work. The authorisation is valid for one year and may be renewed if the exceptional circumstances continue and the company has not yet been able to gather all the information which is needed for a full marketing authorisation.

II. QUALITY ASPECTS

A.  Composition

The product contains active substances inactivated Aeromonas salmonicida and inactivated Infectious Pancreatic Necrosis Virus, and excipients mineral oil (adjuvant), sorbitan sesquiolate monooleate, formaldehyde (residual inactivant), and phosphate buffered saline.

The product is filled into 1 litre capacity sterile, intravenous-like, flexible, ethyl vinyl acetate bags (EVA) with sterile tube sets made of medical grade polyvinyl chloride resin (PVC) and acrylonitrile butadiene styrene (ABS). The filling port of the container is aseptically sealed with a screw cap and port clamp, neither of which makes contact with the final product to be administered. The EVA plastic injection port of the final product container consists of a tube fitted with a puncture septum and sealed with a tear-off cap. Specifications for these containers have been presented. It is stated that the grade for both EVA and PVC used comply with the United States Pharmacopoeia.

The choice of the adjuvant, vaccine strain and inactivating agent are justified. The inactivation process and the detection limit of the control of inactivation are correctly validated.

The product is an established pharmaceutical form and its development is adequately described in accordance with the relevant European guidelines.

B. Method of Preparation of the Product

The product is manufactured fully in accordance with the principles of good manufacturing practice from licensed manufacturing sites.

The product is manufactured using conventional manufacturing techniques. Process validation for full-scale batches will be performed post-authorisation.

Bacterial strains are produced using the established methodologies in conjunction with adding extra glucose to boost the growth of the culture. In the resulting final product, the viable cell density, the optical cell density and the biomass dry weight are specified to be double those which are achieved from fermentation of the same organisms without the batch feeding.

Other than glucose pulse feeding of the batch, the vaccine is produced by standard processes for the production of formalin inactivated bacterial antigens. The bacterial antigen is standardised before formulation by dilution. The bacterial antigen portion is blended with the oil adjuvant prior to filling.

Infectious Pancreatic Necrosis Virus (IPNV) is formulated separately as an emulsified fraction at an equivalent dose. The viral antigen is produced in cell culture and in an in-process test the concentration of viral antigen is controlled by the use of TCID50 assay. The viral portion is blended with the oil adjuvant prior to filling.

Each emulsion, bacterial and viral is bulked separately and to the appropriate ratio in a blend tank and filled in to the final product container.

C. Control of Starting Materials

Details of the manufacture of the active substances inactivated Aeromonas salmonicida and inactivated Infectious Pancreatic Necrosis Virus have been provided.

Starting materials of non-biological origin used in production comply with indicated in-house specifications.

Biological starting materials used are in compliance with the relevant Ph. Eur. Monographs and guidelines and are appropriately screened for the absence of extraneous agents according to the Ph. Eur Guidelines; any deviation was adequately justified

The master and working seeds have been produced according to the Seed Lot System as described in the relevant guideline.

D. Specific Measures concerning the Prevention of the Transmission of Animal Spongiform Encephalopathies

Scientific data and certificates of suitability issued by the EDQM have been provided and compliance with the Note for Guidance on Minimising the Risk of Transmitting Animal Spongiform Encephalopathy Agents via Human and Veterinary Medicinal Products has been satisfactorily demonstrated.

E. Control tests during production

The tests performed during production are described and the results of 3 consecutive runs, conforming to the specifications, are provided.

F. Control Tests on the Finished Product

The tests performed on the final product conform to the relevant requirements; any deviation from these requirements is justified. The tests include in particular fill volume, viscosity, emulsion conductivity, residual formaldehyde, sterility and in vivo safety.

The demonstration of the batch to batch consistency is based on the results of 3 batches produced according to the method described in the dossier. Other supportive data provided confirm the consistency of the production process.

Currently there is insufficient information to agree on a batch potency test which would give sufficient assurances on the immunogenicity of the IPNV components of the batches of the finished product.

It was therefore decided that only a Provisional Marketing Authorisation (PMA) could be granted at this time. It was considered that a qualitative potency test on the final product could be used for the PMA until a suitable alternative method to quantify the antigen content could be validated.

G. Stability

The stability data is not available for IPNV fraction on the final product, however stability up to 36 months has been shown on the bulk antigens. Currently a shelf life of 12 months is justified.

H. Genetically Modified Organisms

Not applicable

J. Other Information

Shelf-life as packaged for sale: 12 months.

Shelf-life after first opening: Use immediately.

III. SAFETY ASSESSMENT

Laboratory trials

The safety of the administration of one dose and an overdose in the target animal is demonstrated in six studies. The investigations were performed according to the recommendations of Directive 2001/82/EC as amended and the relevant guidelines.

Regarding the safety of the administration of one dose, one laboratory study was carried out. Salmon that were seronegative to Aeromonas salmonica and IPNV of less than minimum weight were inoculated with 0.1 ml of the vaccine. A contol group were vaccinated with 0.85% sterile saline. The fish were monitored daily for 28 days at 15°C (420 degree days). Any dead fish were autopsied and swabs taken for culture. The mortalities in the vaccinate and control groups were not significant. There were no abnormal local or systemic reactions observed on gross examination. All fish showed a loss of appetite for up to 5 days post vaccination. This is considered normal. There was no bacterial growth from post mortem after 5 days.

Five studies relating to the safety of the administration of one overdose were also presented. All of these were carried out to the same protocol, and there were only minor differences between the studies. Atlantic salmon with mean weights of approximately 20g (the minimum weight) to 30g (average mean weight 24.5g) were used. The fish were seronegative to Aeromonas salmonicida and IPNV and were of high health status. Safety was documented in a number of fish for each of seven vaccine batches tested. Test fish were inoculated with 0.2ml (double dose) of vaccine. Control fish were similarly treated, but were inoculated with 0.2ml of 0.85% sterile saline. Fish were observed for appetite and behaviour after vaccination, post-vaccination mortality, weight and internal lesions for a period of 21 days. All dead fish were autopsied and swabs taken for culture. At the end of the observation period a detailed post mortem examination was carried out.

Results are reflected on the SPC:

Appetite may be reduced for up to 13 days following administration of the vaccine.
Short term (21 days) safety in 20g fish given double the recommended dose has been demonstrated. The severity of long term lesion development in 20g fish receiving a double dose of vaccine has not been evaluated.

No investigation of effect on reproductive performance was conducted. This is acceptable since the SPC carries the warning:

Do not use in fish selected for broodstock

There are no data suggesting that this product might adversely affect the immune system of the vaccinated animal or its progeny therefore a specific study was not carried out.

The vaccine is inactivated and thus the specific tests to be performed for live vaccines are not applicable.

The adjuvant and excipients used are listed in Annex II of Council Regulation 2377/90 and therefore can be included in products used in food producing animals without a maximum residue limit. Based on this information, a withdrawal period of zero days is proposed.

No specific assessment of the interaction of this product with other medicinal product was made. Therefore, an appropriate warning in the SPC is included.

No information is available on the safety and efficacy from the concurrent use of this vaccine with any other. It is therefore recommended that no other vaccine should be administered within 14 days before or after administration of this vaccine.

Field studies

One large field study was conducted as a multi-centre, parallel-group designed, randomised and blinded trial. The trial was primarily to demonstrate efficacy and consideration was given prior to the start of the number of fish and pens required to ensure the study had sufficient power to detect meaningful differences in mortality rates between treatment groups.

Atlantic salmon (Salmo salar) of mean weight at least 35g, which were seronegative for IPNV, were vaccinated according to recommendations with either Birnagen Forte As Emulsion for Injection for Atlantic Salmon or a vaccine containing Aeromonas salmonicida antigens, but no IPNV. Fish receiving Birnagen Forte As Emulsion for Injection for Atlantic Salmon therefore received 0.1ml per fish given by the intraperitoneal route while anaesthetised. Fish were observed for 21 days post-vaccination, and mortality recorded. Fish were weighed and post-mortem examinations were carried out pre-seawater transfer, and at 3 and 6 months post-transfer.

During the post mortem examination a gross evaluation was made of reactions at the site of injection including assessment of adhesions and melanisation. No significant difference in mortality, adhesions or melanisation was detected between groups.

In general there are no major concerns about the safety of this vaccine. Study findings are reflected in the SPC.

Vaccination may cause some degree of visceral adhesions within the peritoneal cavity, a characteristic of vaccines that incorporate an oil adjuvant. Adhesions may be moderate or even severe if vaccine is not properly delivered into the body cavity. Peak occurrences of side effects in correctly vaccinated fish are typically observed 3 to 6 months post sea transfer. Melanisation of viscera and muscle may also occur.
Observation of a sample of fish from a field study indicated the occurrence of mild (>93%; not noticeable to the layman) and moderate (<7%) adhesions at 6 months post sea transfer.
The user should note that physical and environmental conditions pre-vaccination, at the time of and post-vaccination influence the side effects seen in fish from site to site. These conditions include fish size, health and condition, water temperature, correct vaccination practice including handling and stress pre and post vaccination.

Ecotoxicity

The applicant provided a brief initial environmental risk assessment which showed that no further assessment was required.

Warnings and precautions as listed on the product literature are adequate to ensure safety to the environment when the product is used as directed.

Any unused product or waste material should be disposed of in accordance with national requirements.

IV CLINICAL ASPECTS

Clinical Studies

The applicant has concentrated on demonstrating the efficacy of the new component of this bivalent vaccine, .i.e. the IPNV protection. A single laboratory study has been presented. The study was able to confirm the principles of efficacy, although an anomalous result limits the usefulness of the study. Duration of protection studies are made difficult by the requirement to keep large seawater fish in laboratory conditions. The Applicant has provided evidence that the IPNV efficacy in the form of a comprehensive field trial (described in the safety section of this discussion) has shown its worth by producing results that are unequivocal. The vaccine provided fair to good protection in the target species in the field, even in the face of a strong disease challenge as not all the fish at the sea sites were vaccinated. The efficacy claim is for reduction of IPNV related mortality, and this is therefore supported by the field data. Onset of immunity to IPNV is 655 degree days. The field data supports the claims for duration of immunity to IPN infection at 2100 degree days. The field study was carried out with vaccine that contained the maximum IPNV content, but the laboratory study used vaccines of lower content.

Less data on the furunculosis component of the vaccine have been provided. The only efficacy data provided is that from batch potency tests. The batch potency test involves challenge at between 29 days post vaccination and 43 days post vaccination at 12°C. The onset of immunity to the furunculosis component (Aeromonas salmonicida) is 430 degree days. There is no specific duration of immunity data for the furunculosis component with Birnagen Forte As Emulsion for Injection for Atlantic Salmon.

The only efficacy data for the furunculosis component is from the laboratory since it would be impossible to find sea sites for a field trial that were prepared to have an unvaccinated furunculosis control group. This is accepted.

Study findings are reflected in the SPC.

For active immunisation against Aeromonas salmonicida and Infectious Pancreatic Necrosis Virus (IPNV) to reduce furunculosis and IPNV related mortality of Atlantic salmon populations.
Onset of immunity for A. salmonicida occurs within 430 degree days following vaccination. Onset of immunity for IPNV occurs within 817 degree days following vaccination.
Duration of immunity for A. salmonicida and IPNV is unknown.
Efficacy has not been fully evaluated.

V OVERALL CONCLUSION AND BENEFIT– RISK ASSESSMENT