Vaccine handling and storage tips

As farm veterinary medicine has shifted its focus towards disease prevention wherever possible, vaccines have played an increasing role, alongside consideration of flock and herd management, to optimise health.

Without doubt they can be a useful tool, but do farm clients always get the results they should from vaccines, and if not, why not?

In this article, Charlotte Hockings from Westpoint Farm Vets – part of the VetPartners group – reflects on how storage and handling of vaccines could be impacting efficacy, and how best to work with farm clients to enable them to reap the full benefits of vaccinating their animals.

Vaccines storage requirements

Most vaccines need to be kept at temperatures between 2°C and 8°C, right up to the point when they are administered to the animal.

Ms Hockings said: “This is because the antigens in the vaccine, which antibodies bind to as part of the immune response, are complex, three-dimensional structures. Changes in temperatures outside of a certain range can cause antigens to unravel and change shape, which makes the vaccine less potent or, at worst, ineffective.

“This is why it’s important for vaccines to be kept at a safe temperature throughout the entire cold chain, from when they are made, during any periods of transport, up to when they are administered to an animal.”

Ms Hockings highlighted that vaccines react to temperature in different ways, depending on their type.

She said: “Live vaccines are most affected by temperatures that are too high, while inactivated vaccines are more sensitive to freezing.”

On-farm vaccines storage

Ms Hockings explained on-farm storage of vaccines tends to be a weak point in the cold chain, potentially leading to reduced efficacy, which was confirmed by research carried out at the University of Bristol in 2018.

She said: “A typical farm fridge may be an old domestic fridge, kept in an uninsulated and unheated outbuilding, possibly with other items kept in it, alongside vaccines, so the door may be opened and closed regularly leading to fluctuations in temperature.”

Data loggers with temperature probes were placed in 20 farm fridges in the south-west of England, which recorded data from January through to August. The majority of fridges in the study failed to keep vaccines within the recommended storage temperature range, between 2°C and 8°C, with the highest temperature recorded at 24°C and the lowest recorded at -12°C.

Ms Hockings said: “The study found that the fluctuation in the external temperature influenced the internal fridge temperatures. This probably doesn’t get thought about, as domestic fridges are inside insulated houses or offices, but farm fridges tend to be more exposed to seasonal extremes.”

Ms Hockings highlighted that even the best attempts to keep vaccines within fridges on farm were not necessarily as effective as the farmer might expect – especially if fridge temperatures were not monitored.

She said: “On-farm fridges would benefit from temperature probes to record the maximum and minimum temperatures reached, which can be checked frequently to pre-empt any vaccine failure from storage.

“Storing vaccines in the middle of the fridge, rather than in the door or at the back, also helps keep them at a stable temperature.”

Communicating importance of temperature to farm clients

For Ms Hockings, making her farm clients aware of the importance of storage temperature is crucial, but it can be a difficult message to communicate.

She said: “It’s tricky, because, as vets, we’re limited by how much influence we can have. Most of our farmers use Farmacy for medicines and vaccines, so it’s hard to know whether they’re going straight into fridges on arrival.

“When farmers pick up vaccines from the practice, I always make sure it moves straight from the fridge to the cool pack for travel, and make a point of saying that it needs to go straight in the fridge when they get back to the farm – and must stay cool right until it goes in the animal. But again, it is difficult to know how effectively it is being done.”

One key opportunity to discuss vaccines storage is while completing herd or flock health plans – a requirement for all Red Tractor assured farms.

She said: “There is a section on vaccines, and although there is nothing specifically on storage in the standard, it can be a good time to bring it up while having a wider discussion on what can be done to help ensure the efficacy of vaccines used on farm.”

The other main opportunity to raise the subject is when out on-farm and observing something that is not right.

Ms Hockings said: “I’ve been on-farm and seen a bottle of vaccine just sat in a medicine cupboard or left out to one side of the cattle crush for an extended period.

“In situations when you notice vaccines being stored or handled incorrectly on farm it is possible to bring it up and explain that if the vaccine isn’t kept at the right temperature, it won’t be as effective at providing immunity for the disease it is designed to prevent.

“Not only does this make the vaccine itself a waste of money, but we may end up needing to treat the affected animals with antibiotics, which usually impacts on production, as sick animals achieve poorer growth rates or produce less milk.

“Some commonly used vaccines, like Heptavac in sheep, do not require a veterinary prescription, so the [registered animal medicines advisors/SQPs] need to be ensuring farmers are aware of the storage requirements in that situation.”

Dealing with ineffective vaccines

In some cases, an animal becomes unwell with a disease it has been vaccinated against.

Ms Hockings said: “It is, unfortunately, really difficult to provide a reason why a vaccine may not have worked in these situations.

“Some farmers expect a vaccine to act as a ‘silver bullet’, which will protect in all circumstances, but in reality, the environment, disease load and management all play a role.

“For example, with pneumonia vaccines, it is very important that the airflow and stocking density in the shed is right to fully protect youngstock.

“A few vaccines, such as those for footrot in sheep or Escherichia coli in mastitis, are aimed at reducing the clinical symptoms rather than eradicating it or completely avoiding clinical disease. This makes it hard to say that a perceived failure was definitely down to how it was stored, even if that’s your educated hunch.”

Conversations on vaccines

At Ms Hockings’ practice, the Horsham branch of Westpoint Farm Vets, handling of vaccines tends to come up as a topic in smallholder meetings, but she thinks opportunity exists to discuss vaccines’ storage more with larger farm clients, who do all the administration themselves.

She said: “As social distancing requirements continue to ease, it would be good to gauge interest among our farm clients for a vaccine-focused meeting or training session.

“Vaccines have been around for a long time; for example, clostridial disease vaccines have been widely used for years. But as the list of diseases we can vaccinate for continues to grow, it will be beneficial to spend more time with farmers raising awareness of vaccine options, plus handling and storage.”

Evaluating vet phase of the cold chain

As well as thinking about how vets talk to farm clients about how to keep vaccines cool, Ms Hockings thinks room exists for veterinary practices to review their section of the vaccines cold chain, to check whether improvements can be made.

She said: “In the equine sector, it is quite common for vets to have car fridges, ensuring they have full confidence that the vaccines are stored at the correct temperature while travelling. This is less common in the farm sector, because most clients collect from the practice to administer themselves, or order vaccines online.

“However, for practices with an increasing number of smallholder clients, it could be worth investigating. Smallholders often prefer a vet to support them with administering vaccines, which means more vets transporting vaccines direct to farm.”

Even without investing in car fridges, other changes are possible that could give vets more confidence vaccines are being kept at a steady temperature while travelling.

“Swapping cool bags for hard cool boxes with a temperature probe could be beneficial to achieve peace of mind they are not being compromised during travel, even if vaccines are only being transported in vets’ cars infrequently.

“The boxes hold their temperature better and for longer than the cool bags with ice underneath, which can often be too cold at the bottom and too warm towards the top.

“Practices can look at their client base and systems, and evaluate whether there’s an opportunity for improvement. This could complement proactive conversations with our clients about how to minimise storage issues, to help our clients get the most out of the vaccines they choose to use to protect their herd or flock from disease challenges.”