Monitoring fridge temperatures

Vaccines have a major role to play in disease prevention, but how they are stored impacts on efficacy and may result in compromised animal health and financial loss.

The recommended storage temperature for most vaccines used in cattle, sheep and pigs is between 2 - 8°C. Live vaccines are more sensitive to damage at raised temperatures, whereas inactivated vaccines are more stable to moderate heat exposure, but more sensitive to freezing.

MSD Animal Health’s Fridge Check survey revealed interesting results when carried out on fridge temperatures across 19 farms in the south west of England. On each farm, three data loggers were used; two inside the fridges and one in the room where the fridge was situated. The temperature was recorded every 30 minutes.

None of the fridges maintained an internal temperature of 2-8°C during the study period, with 16 fridges having at least one reading above 8°C.

The maximum temperature recorded was 24°C. There were 11 fridges with at least one reading at, or below, 0°C, with the minimum temperature recorded being -12°C.

In a large percentage of fridges, the temperature was outside the required storage range for a long enough period to affect vaccine efficacy.

Paul Williams, MSD technical manager for ruminants, says: “On-farm storage is the weakest link in the vaccine cold chain. Vaccines are extremely fragile, and any damage is irreversible. It is not possible to tell just by looking at it if a vaccine is any good."

“If you are going to store vaccines on-farm, you must measure the maximum and minimum temperature daily. Maximum/minimum thermometers can be bought for as little as £10 and data loggers for £20-£30. More expensive technology is available which will send text alerts and alarms if the temperature goes out of range.

Vaccines should also be stored in the correct place within the fridge, not at the back where they may freeze, or in the door where the temperature will go up each time it is opened.

Its age, where it is situated, and the outside temperature will affect a fridge’s efficiency.

Domestic fridges are designed to operate at room temperature and can only bring the temperature down; they cannot bring it up.

In an ideal world, do not store vaccines on farm, but if you do, use as soon as possible and use a cold bag when collecting them. Vaccinating many animals can take a long time, so do not get all the vaccine out of the fridge at once.”