Data loggers and cold chain management: What you should know

Who could have seen that coming? In the era of COVID-19, “cold chain” has become a household phrase.

Or, if we’re not at that level yet, at least more and more people are thinking about what it takes to transport products over long distances, store them, and deliver them to end-buyers while keeping them at punishingly cold temperatures — sometimes below the average temperature of Antarctica!

Of course, the COVID-19 vaccines have sparked this interest in cold-chain management. Three vaccines have received emergency use authorization from the US Food and Drug Administration, received approval from the CDC, and are in the process of the most vast logistical rollout effort in human history.

All three of these vaccines have different cold-chain requirements. The mismatch is almost comical:

• Johnson & Johnson vector vaccine: 2 to 8 degrees Celsius
• Moderna mRNA vaccine: -15 to -25 degrees Celsius
• Pfizer/BioNTech mRNA vaccine: -60 to -80 degrees Celsius

The sub-glacial refrigeration needs of the Pfizer/BioNTech vaccine presents a logistical challenge — how do you get such a sensitive vaccine to remote corners of the country, and later the world? Will they even have the cold-storage capacity to keep the vaccine potent when it arrives?

According to Dickson, data loggers are essential for monitoring many types of sensitive products. It’s worth revisiting the role that digital data loggers play in maintaining this cold chain. After all, tens of thousands of lives depend on it, with thousands more relying on the vaccine to guard them against serious illness with long-term consequences. It matters to get this right.

Here are four critical things to know about digital data loggers and their usefulness in cold-chain management, like the child chains required to distribute the COVID-19 vaccines:

1. Not all data loggers have the accuracy needed to manage every cold chain
Just to quickly review, a data logger consists of three main components:

• The sensor, which detects conditions like temperature.
• The processor, which interprets the inputs from the sensor.
• A data storage drive, which records the data interpreted by the processor.

With the data storage drive, it is important to make sure it has enough capacity for the volume of data you will collect. More importantly, though, you need to make sure you select a data logger for your cold chain that is sufficiently accurate.

There are two potential points of failure here — the sensor and the processor. In the case of sensors, not all thermometers are created equally. Some data loggers use temperature sensors designed for the food industry.

They are sensitive enough to detect the kind of temperature changes that could spoil food, but they may not have the fine sensitivity to detect the kind of slight change in temperature that could ruin a vaccine.

By contrast, data loggers developed for the pharmaceutical industry come equipped with temperature sensors powerful enough to detect the range and minute change needed to protect the potency of a vaccine — even if the vaccine needs to be stored at -70 degrees Celsius.

Data loggers also differ in the resolution of the processor, measured in bits — 8-bit, 12-bit, 16-bit, etc. Thus number tells you not how accurate the sensor is, but how finely the processor can interpret the sensor input.

The sensor might be able to detect the same 100-degree temperature range. A 12-bit processor could resolve that input into over 4,000 pieces of data–but a 16-bit processor can resolve that same 100-degree range into over 65,000 pieces of data. This means that it can detect a much more minute change in temperature.

When considering the right data loggers for cold chain management, make sure the sensor is accurate enough, the processor capable of sufficient resolution, to do what you need it to do.

2. Cold chain data loggers may need multiple sensors
The traditional data logger has one sensor to detect one condition — temperature, pressure, humidity, etc. Some data loggers can have the sensor switched out, so the same processor can be used to detect different parameters.

Modern data loggers, however, may be equipped with multiple sensors. This kind of data logger plays an important role in cold-chain maintenance. While temperature is arguably the most important condition to monitor when a vaccine must be kept cold, conditions like humidity, air pressure, shock pressure, and air quality may be important too.

The best data loggers for cold-chain management measure multiple conditions at once to preserve the integrity of the temperature-sensitive cargo.

3. Cold chain data loggers may need variable sampling frequency
Digital data loggers can come equipped with long battery life, but the fact remains that the more often you take a reading, the faster you drain the battery.

Data loggers that monitor the cold chain of food products may be set to record temperatures at intervals as long as 30 minutes to preserve battery life. The sensitivity of the product is such that this long interval may be sufficient.

When we’re talking about a vaccine, however, lives are on the line, and a whole batch could be spoiled if the cold chain falters within that 30-minute interval. Cold chain managers should consider setting the data logger for much shorter intervals — five minutes, or even less depending on whether the vaccine is in transit or in storage.

The challenge then becomes managing battery life, especially in cold temperatures where the battery can drain faster.

4. IoT data loggers can alert logistics personnel of temperature increases in time to save the vaccine
Of course, the last point presumes that the data logger has the ability to alert cold-chain managers of a significant change in temperature.

This hasn’t always been the case. Data loggers of the past could record, but not alert. They could tell you when the temperature rose high enough to spoil the vaccine, but not in time to intervene.

The rise of the Internet of Things (IoT) has changed that. Modern data loggers can connect to WiFi or mobile data and send emails, push notifications, or other alerts if conditions fall outside the set parameters — say, if vaccine storage gets warm enough to threaten the vaccine’s efficacy.

Alerted in time, cold chain managers can potentially take corrective action to save the valuable vaccine before it overheats and spoils.

Products like the COVID-19 vaccines are miracles of science that deserve equally miraculous solutions to keep them safe and potent. Cold-chain managers should familiarize themselves with modern data logger technology — the accuracy of the sensors, resolution of the processors, multi-sensor data loggers with variable sampling frequency and IoT connectivity. To preserve a lifesaving cold chain, the investment is worth it.