The use of vaccinations in livestock will become increasingly more important with the rules around the use of antibiotics due to change this month (January).

The Covid-19 global pandemic has also highlighted the importance of vaccinations and how they can be used to prevent the spread of disease / infection.

Vaccinations are quite expensive and take time to work so they should be administered well in advance of when they may be required.

How vaccines work

Vaccines stimulate an animal’s immune system without infecting them with the disease. Vaccines help to prevent disease and work best when used in groups.

If a vaccinated animal comes in contact with a disease, the animal’s immune system will recognise it and immediately produce the antibodies needed to fight the disease-causing bacteria.

Vaccinations are a worthwhile investment in farms that suffer from disease outbreaks. Outbreaks can often be unpredictable and can have a major financial impact on farms.

Some vaccines are suitable for use in pregnant animals, which can increase antibodies in colostrum. This helps to protect their offspring from possible diseases.

It is important when administering a vaccination that the instructions are followed.

Vaccine types

There are two main forms of vaccinations - inactivated and live vaccines. Inactivated vaccines contain a tiny part of the disease organism, which is dead.

Live vaccines contain a live organism that is closely related to the disease-causing organism or bacteria.

The live organism is either a non-harmful strain or a weakened strain, so it can no longer cause the disease.


Firstly, it is important to note that vaccinations are not going to be 100% effective, but they should reduce the likelihood of an outbreak and reduce the level of illness caused by the disease.

There are three main reasons why a vaccination will not work, outlined below.

1. The animal

Despite being given a good vaccine that was administered correctly, animals may still get sick.

Like the Covid-19 vaccinations, some people who have been vaccinated have still contracted the virus.

The reason why the vaccination did not work can be extensive, but is usually associated with the animal's environment. Healthy animals that are under some form of stress from the environment will not respond properly to vaccines.

2. The person giving the vaccine

Another reason why a vaccination may be ineffective can be due to the competence or ability of the person administering the vaccine.

There is a wide variety of vaccines available, so instructions for the vaccination should be read before they are administered. Live vaccines are particularly fragile. If they become either too hot or frozen, their effectiveness will be reduced.

Dosage requirements are usually different to other medicines. There is often a set dosage rate, with no variation due to weight.

3. The vaccine

Another reason why vaccines do not work is if the wrong one is used to control disease. You should consult with your vet and use the correct vaccination for the disease you are trying to prevent.

A vaccine can also fail where the disease challenge is too high or where a proper booster shot was not given.

It is also possible that the vaccine administered may be ineffective. It is possible that there was an issue during manufacturing that caused it not to work properly.

Obviously, the expectation is that quality-control measures during the manufacturing process were good enough to stop this from happening.