Fish Immunology (1+1)

Unit 14 - Vaccine

14.9. Injection vaccination
Vaccination by injection works well with fish that are 5–10 g or larger and the injection vaccination is very popular in salmon industry. Light anaesthesia is given to the fish before injection to prevent mechanical injuries and also to overcome handling stress. Vaccine can be administrated through intramuscular or intraperitonial with intraperitonial vaccination is beeing very common. The immune response development depends on the needle and method of injection. Short needles might deliver the vaccine in the muscle and cause inflammation and a bad immune response, while long needles may damage the internal organ. The right thickness of needle is also important because the viscous vaccine has to pass through the needle and if the needle is too large the vaccine may fall back and may lead to infection. Once vaccination is administrated it will take weeks to develop immune response, so it is important maintain the fish in ambient temperature and not to stress fish because temperature variation and stress may suppress the immune system.
Advantages

• Provide protection for long duration
• multiple antigens can be administrated in single injection
• every fish in farm can be vaccinated
• every fish in farm receives the correct dose
• Highly efficient in generating both humoral (antibody) and cellular cytotoxic response

Disadvantages

• Needs sophisticated machinery or large skilled workforce
• Significant handling stress and risk of post vaccination fungal infections
• Local reactions
• Unsuitable for small fish