To answer your question, we will have to first discuss why we vaccinate and how vaccines work.

A growing global population has increased the demand for livestock products and to meet the demand, traditional farming systems have changed to more intensive farming systems. Furthermore, climate change and imports and exports of livestock have led to the introduction and simultaneous increase in the number of diseases being reported. For example, bluetongue virus in sheep was first reported in South Africa more than 125 years ago, when European sheep breeds were shipped to the country.

To control the rising disease challenge and meet the demand on livestock products, vaccines have shown to be efficient in preventing the transmission of infection, not only between animals but also between animals and humans. They also indirectly increase fertility and production, ensure that livestock products are safe for human consumption, and provide a cost-effective strategy in the control of animal diseases.

Vaccines do this by stimulating the immune system, preparing the animal’s immune system to defend itself against disease-causing microorganisms that the animal may encounter later in life. The need for antibiotics is also reduced when vaccines are used appropriately, thus reducing the threat of antimicrobial resistance in animals and humans. They also help eradicate diseases from your herd that are present. It is important to have a well-thought- through vaccination programme in place for your farm.

There are different types of vaccines, which are formulated in different ways. Some contain parts of an organism, some a weakened organism, and some a killed organism. These organisms can be viruses, bacteria, or even protozoa. The parts of or whole organism
in the vaccine is called an antigen. Antigens in the vaccines function as a trigger to the immune system to form antibodies and memory cells that will respond quickly when the actual pathogens are introduced in future.

The other constituents of a vaccine, in brief, include:

• Preservatives, which prevent the vaccine from being contaminated.
• Stabilisers, which prevent reactions from happening within the vaccine during storage.
• Some vaccines come with a diluent, which is a liquid used to dilute the vaccine to the correct concentration.
• Residuals are inactive substances that boost the immune system.
• Some vaccines may also have an adjuvant, which helps create a stronger immune response.

With so many ingredients and formulation forming part of the development of a vaccine, it is easy for any part of the process to go wrong and this can result in disease, have detrimental side effects, or cause the vaccine to be ineffective in eliciting an appropriate immune response.

When you choose a vaccine for your herd, you want to make sure that you choose a vaccine that is safe to use in animals, has limited side effects, is potent in generating an immune response, is effective, and also that you know who to call if anything goes wrong with your herd after administering the product. Furthermore, consumers today are more wary of what is in their food, so you want to be reassured that animals will be safe for human consumption if your herd has received vaccines at any point in their production cycle.

You want a good vaccine, backed up by scientific results and rigorous testing, and these are registered vaccines.

Fortunately, the manufacturing, importing, distribution, and use of vaccines are strictly regulated in South Africa. A vaccine for the use in animals must be registered. The acts responsible for the manufacture and registration of vaccines in South Africa are the Animal Diseases Act (35 of 1984), the Medicines and Related Substances Control Act (101 of 1965 and amended in 2008), and the Fertilisers, Farms Feeds, Agricultural Remedies and Stock Remedies Act (36 of 1947).

It is only in case of an emergency, where there is an outbreak of a disease and there is no registered vaccine available in the country against that disease, that it may be necessary for government to allow the emergency registration of a vaccine. There are specific requirements that this vaccine must meet to allow emergency registration. The emergency vaccine could either be allowed following the approval of an application for a permit from the Medicines Control Council for a Section 21 exemption in terms of the Medicines and Related Substances Control Act (101 of 1965, as amended by Act 90 of 1997), and an import permit granted from the directorate for animal health for the vaccine to enter the country if the vaccine is to be imported; alternatively, it could be a local manufacturer that adheres to the requirements of the Act, as in the case of the recent bluetongue virus vaccine that received emergency registration.

Autogenous vaccines, which are emergency vaccines that are not registered, can only be used under strict veterinary supervision for one farm for which this vaccine was produced. If an autogenous vaccine must be used on an adjacent farm, an application in terms of Section 20 of the Animal Diseases Act (35 of 1985) must be submitted for approval.

Furthermore, before a vaccine is registered, it must have successfully undergone pre-clinical trials, that is, a form of testing that determines if it will trigger the host to produce sufficient antibodies; and that it does not result on the spread of the disease after vaccination. It also tests for safety, appropriate dose, withdrawal periods, and adverse reactions. Thereafter, the vaccine would still be re-tested by authorities, and only then can it be registered.

To verify if a vaccine is registered, the product label and insert will have a code; Reg. No. followed by (Act 36/1947).

Therefore, registered vaccines are vaccines that have been scientifically proven to be safe for humans and animals, effective for animal use, and will not result in the further spread of the disease. Currently, there is a variety of registered vaccines available in South Africa and South African pharmaceutical companies are tirelessly working to manufacture and register new products that will help improve and maintain animal health.

Wolboer/Wool Farmer | Vol 11 Nr 3 • 2023