Preventing Accidental Freezing in Vaccines
Preventing accidental freezing in vaccines is a prevalent problem throughout the world. All vaccines that have aluminum salt adjuvant are more likely to encounter freezing. Cold is often a more significant threat than heat in the delivery of vaccines. When a vaccine is frozen, its potency may be reduced. This may lead to the administration of ineffective vaccines. Freezing of vaccines tends to occur when exposed to sub-zero temperatures during the cold chain process. Due to this, national immunization programs may be put at risk. Some immunization programs may be vaccinating patients with compromised vaccines. When patients are administered ineffective vaccines, there is still a high possibility for them to be infected with the disease they were vaccinated against. Given the possible wide-scale immunization program and distribution of degraded vaccines, an outbreak of vaccine-preventable diseases can eventually occur.
Examples of these are liquid compounds are:
- Haemophilus Influenza Type B
- Hepatitis A, Hepatitis B
- Diphtheria Toxoid
- Tetanus Toxoid
- Human papillomavirus
- Liquid Japanese Encephalitis
- Liquid Rabies
- Liquid Meningococcal
- Liquid Pneumococcal Vaccines.
Vaccines need to be transported in a temperature-controlled supply chain, otherwise known as the cold chain. It begins with the production of the vaccine from the manufacturer. It ends when it is administered to the patient. Due to historical data, shipping guidelines often recommend that vaccines and biologics need to be kept between 2° and 8° C (35.6° and 46.4° F).
Prioritizing the protection of the vaccines from heat may cause the vaccines to get exposed to freezing temperatures. Most of the widely used vaccines globally are freeze sensitive like Tetanus, Pertussis, Diphtheria, Liquid Haemophilus influenza type b (Hib), and Hepatitis B.
PATH conducted an analysis and discovered that accidental freezing tends to occur in various segments of the cold chain. In developed countries, vaccines had a 16.7% chance of getting exposed to freezing temperatures during transport. Meanwhile, developing countries had a 35.3% chance of the possibility of exposure to a temperature excursion. Freezing temperature exposure occurred not only in areas with limited resources but also happened in regions that have more resources. Additionally, the differences in occurrence between the two were not significant. PATH also discovered that in the six studies they analyzed, more than 75% of vaccine shipments encountered freezing temperatures. This can lead to a disastrous cold chain maintenance failure.
The Worldwide Health Organization (WHO) is coordinating with vaccine manufacturers to label vaccines. The label will reflect their real temperature stability. This will allow countries to manage the controlled temperature chain when needed. A controlled temperature chain is an option for heat-stable vaccines that have been determined to be for higher temperature storage.
Several cold chain equipment is being developed to allow better freeze protection. The WHO has recently released specifications for freezer-safe cold boxes. They are also in the process of producing specifications for freeze-safe vaccine carriers.
During transport, cool water packs can be used instead of frozen ice packs inside the cold boxes. As recommended by the WHO, the ice packs should be allowed to melt first before they are placed inside the transport. It is vital for vaccine managers and cold chain staff to be properly trained and knowledgeable about freeze-sensitive vaccines. Additionally, vaccine handling procedures should also be laid out and disseminated as well.
Ensuring that the best possible refrigerators are available at the facility reduces the possibility of vaccine freezing. Installing proper electronic monitoring devices can mitigate risks. This is done by sending real-time alerts to signal temperature excursions.
Storage Best Practices for Frozen Vaccines
When storing vaccines, they should be unpacked immediately. They should be placed in trays or containers that allow proper airflow. Vaccines that are near their expiration date should be positioned at the front. They should be kept in their original boxes with their lids tightly closed to prevent unnecessary light exposure. They should also be separated and labeled by type. Then, determine whether public or private.
The thermostat should always reflect the midpoint temperature or the factory setting. It is important to ensure that the temperature remains within the allowable range at all times. Once a temperature falls out of range, it should be reported immediately. Whenever it becomes too hot or too cold, the necessary actions and steps should be taken as soon as possible. The designated standard operating procedures should be followed.
For proper temperature monitoring, the freezer door should always be closed. Water bottles can also be used to regulate and maintain consistent temperatures. A two to three-inch space between the vaccine containers and freezer walls should be allotted for proper temperature regulation and airflow. Overcapacity in containers can have detrimental effects. It is important that vents are not blocked to allow proper airflow.
It is essential to avoid using dormitory-style refrigerators or freezers for vaccine storage. This is because they are more susceptible to freezing vaccines. Combination style refrigerator or freezer units should also not be used as well. Staff should also avoid using medical-grade refrigerators for personal use by storing food and other personal items. When staff uses these refrigerators for personal matters, the door gets opened more frequently. This makes the vaccines inside the unit more susceptible to temperature fluctuations. Vaccines should not be stored on the shelves located in the freezer doors. Doing so will expose them to external temperatures when the door is opened.
Continuous temperature monitoring
Using sub-standard cold chain equipment instead of the recommended medical refrigerators put national immunization programs at further risk. Many middle-income countries rely on cheap domestic refrigerators and cold boxes to store and transport their vaccines. This is because of the lack of available funds for higher quality refrigerators. Fortunately, domestic refrigerators with new continuous temperature monitoring technologies and other innovative technological interventions have been found to reduce accidental exposure to freezing temperatures.
Continuous temperature monitoring solutions detect temperature changes and freeze events even. They are able to do so without the presence of health workers. It also allows health workers to analyze temperature data in real-time. This enables them to take the necessary steps in the event of an excursion. They are also able to perform the standard operating procedures as a response to the situation.
AKCP temperature monitoring solutions can also detect which refrigerators need to be replaced. They also identify which thermostats need to be adjusted. By practicing continuous temperature monitoring as a standard, overall cold chain management can be strengthened as a result.
Case Study: Vaccine Freezing in Indonesian Cold Chain
A study was conducted by Carib M. Nelson et al. to analyze the occurrence of freezing vaccines in the Indonesian cold chain. In order to measure the temperature of the Hepatitis B vaccine shipment, Data Loggers were used. The temperature was observed from the manufacturer up to the point of its administration. A baseline condition and three intervention phases were set up and monitored.
It was found that freezing temperatures were recorded in 75% of baseline shipments. The most sizeable freezing rates occurred during the transport of vaccines from the province to the district, health center storage refrigerators, and district-level ice-lined storage refrigerators. The interventions applied reduced freezing but without unwanted heat exposure.
Several publications show that the freezing recorded in this case study is not limited to Indonesian provinces only. The exposure of 75% hepatitis B vaccines to sub-zero temperatures is congruent with serious vaccine freezing problems in different parts of the globe. This includes developed countries. Due to the growing data of widescale freezing in the cold chain, actions must be executed to limit the exposure of freeze-sensitive vaccines to freezing temperatures. Vaccine freezing would impair global immunization efforts and the distribution of new vaccines to developing countries.
Accidental freezing of freeze-sensitive vaccines is prevalent in Indonesia. However, strategies can be used in order to reduce freezing. Some of the ways to minimize freezing are selective transport and storing vaccines at ambient temperatures. The most straightforward approach to minimize freezing among the interventions is through cold boxes without ice packs. Frozen ice packs placed directly inside vaccine carriers will cause internal temperatures in the carriers to fall below 0°C. This puts freeze-sensitive vaccines at the risk of getting exposed to harmful temperatures. Vaccine vial monitors have also been proven effective in mitigating risks and prevent heat-damaged vaccines. They identify vaccines that have been exposed to extreme heat conditions. This helps the staff discard the degraded vaccines.
The study demonstrated that allowing higher temperatures in various stages of the cold chain vaccine distribution system can reduce freezing. Vaccines stayed within the cold chain’s managerial capacity to ensure that the cold chain discipline is implemented throughout the process. The higher temperature ranges were regulated to short-term transport stages of the cold chain to avoid prolonged heat exposure. Policy changes can also contribute to the reduction of freezing vaccines. Allowing limited storage of freeze-sensitive vaccines with >2–8 °C temperatures would pave the way for more flexible distribution strategies. This will help lessen costs and increase storage capacity.
The study does not suggest that it would be applicable to other cold chain situations nor imply that cold chain practices are limited to what was described. Local conditions and specific cold-chain weaknesses need to be considered and evaluated before new approaches are implemented in vaccine distribution.