Multiple vaccine scrapping incidents occurred in the United States, and large-scale vaccination tested global vaccine "express delivery"

Recently, there have been many vaccine scrapping incidents in the United States. As biological products, vaccines are extremely sensitive to temperature. Large-scale vaccination will test the global vaccine "express delivery". How can the medical cold chain withstand the test?

Written by reporter Li Li Edited by Ding Lin

New Media Editor/Fang Yongzhen

Interview experts:

Liu Baolin (Dean of the School of Medical Devices and Food, University of Shanghai for Science and Technology)

Safe and effective vaccines are one of the most powerful means of preventing infectious diseases. However, as a biological product, vaccines are sensitive to temperature and can be affected by temperatures that are too high or too low.

For example, the mRNA COVID-19 vaccine developed by Pfizer and BioNTech needs to be stored at around -70°C. The harsh storage conditions also caused some vaccines to be scrapped during transportation. In December last year, some of the Pfizer vaccines shipped to California were urgently returned (3,000 doses) because the temperature dropped to -92°C during transportation. Subsequently, similar anomalies occurred during the transportation of the same vaccine to Alabama and New Mexico. Multiple vaccine scrapping incidents have not only affected local epidemic prevention and control, but may also undermine people's willingness to be vaccinated.

▲Pfizer-BioNTech COVID-19 vaccine (picture from the Internet)

Liu Baolin, dean of the School of Medical Devices and Food at the University of Shanghai for Science and Technology, has long been engaged in research on low-temperature biomedicine and food freezing and refrigeration. In an interview with reporters, he said, "Vaccines are biological products. To ensure the quality of vaccines, they must be stored and transported under the prescribed cold chain conditions. The new coronavirus vaccine is no exception. However, the new coronavirus vaccines developed through different technical routes have different temperature requirements for cold chain transportation, which is determined by the characteristics of the vaccine itself."

Compared with medicines and other vaccines, what are the special features of the cold chain process of the COVID-19 vaccine? Can the vaccine cold chain withstand the pressure?

Pharmaceutical cold chain is the "top of the pyramid" in the industry

Mi Feng, spokesperson of the National Health Commission, introduced at a press conference of the State Council's Joint Prevention and Control Mechanism held on February 4 that as of 24:00 on February 3, a total of 31.236 million doses of new coronavirus vaccine had been reported for key populations nationwide.

From a regulatory perspective, the quality of the vaccine is the first factor to be considered. Not only the quality control of each production link cannot be sloppy, but temperature control in the storage and transportation link is also a very important aspect. As the first round of COVID-19 vaccination was urgently carried out across the country, people found that large-scale vaccination not only tests the vaccine production capacity, but also the cold chain transportation and distribution capabilities.

However, unlike the general fresh food cold chain, the technical threshold of the vaccine cold chain is higher.

Pharmaceutical cold chain transportation is also known as the "top of the pyramid" in the cold chain industry. "Compared with the food cold chain, the vaccine cold chain has stricter requirements on equipment temperature stability," said Liu Baolin.

▲In India, a health worker uses an incubator to deliver vaccines (Source: UNESCO)

In order to ensure the medical effect of vaccines, relevant cold chain facilities and equipment are usually required to carry out cold chain management throughout the entire process. There must be no "chain breaks" during transportation, otherwise it will cause harm to public health. The World Health Organization predicts that about 50% of vaccines are wasted worldwide each year, largely due to the lack of temperature control systems and equipment facilities.

What is the current status of vaccine cold chain in my country? Liu Baolin said that my country currently has relatively sound vaccine cold chain standards and regulations, but there are still some shortcomings in pharmaceutical cold chain logistics, such as uneven regional development, the cold chain level of front-end production enterprises in the supply chain is stronger than that of the back-end, and the differences between terminal distribution companies; at the same time, the medical cold chain still has problems such as the lack of large-scale and professional operation, immature third-party logistics, lack of professional management personnel, and low technical level.

Inactivated vaccines already have a sound cold chain

At present, the first batch of vaccines approved by the National Medical Products Administration for vaccination in my country are inactivated vaccines. Inactivated vaccines are one of the "five technical routes" for China's new crown vaccine and are also the traditional way of vaccine production. In fact, the "DPT" vaccine, rabies vaccine, injectable polio vaccine, smallpox vaccine, etc. are all inactivated vaccines.

Inactivated vaccines have a long history, mature technology, and are relatively easy to preserve, making them the safest form of vaccines. Therefore, domestic companies and disease control agencies can use existing cold chain equipment (cold storage, refrigerated trucks, medical refrigerators, etc.) in the storage and transportation of COVID-19 vaccines.

▲A cold chain truck loaded with inactivated COVID-19 vaccines departs from the Beijing Institute of Biological Products of Sinopharm Group China National Biotec Group (Photo source: Xinhua News Agency)

In addition, my country's "Vaccine Management Law", "Vaccine Storage and Transportation Management Regulations", "Vaccination Work Regulations" and other regulations have specific provisions on the cold chain requirements for vaccine storage and transportation. For example, the "Vaccine Storage and Transportation Management Regulations" (2017 edition) has specific provisions for several important links.

In general, over the years, various government departments, including enterprises and vaccination links, have formed a complete system to maintain the overall order of vaccination. For the transportation and storage of conventional vaccines, there is no essential difference between domestic and foreign standards.

"The transportation and storage of inactivated vaccines need to be carried out in an environment of 2℃~8℃. The current industrial chain is relatively complete and the technology is mature," Liu Baolin commented.

Vaccination is proceeding in an orderly manner, and there is no pressure of "breaking the chain"

Compared with conventional biological preparations and vaccines, the supply chain of the new crown vaccine does have its own particularity. This particularity lies not only in the challenges posed to temperature control in the storage and transportation of the new crown vaccine, but also in the urgency of time. Every country hopes to control the epidemic as soon as possible, and how to obtain the vaccine and how to store and use it after obtaining it all need to be taken into consideration.

▲At the end of January, Morocco approved the emergency use of China National Pharmaceutical Group's new crown inactivated vaccine (Source: AP)

The first COVID-19 vaccine launched in my country has begun to be administered to key groups in many places. For example, starting from January 1 this year, Beijing organized various districts to carry out COVID-19 vaccination work for nine key groups, striving to achieve "all those who should be vaccinated should be vaccinated" on the basis of informed and voluntary consent.

But as the demand for vaccination continues to grow, will it trigger a cold chain disruption "crisis"?

"The supply chain for the COVID-19 vaccine will be one of the most complex (pharmaceutical logistics) supply chains in history," said Dai Tinglong, professor of medical operations management at Johns Hopkins University in the United States. If the approved COVID-19 vaccine is to be vaccinated on a large scale, it will undoubtedly face a "big test" of cold chain transportation and special packaging.

Ren Peng, general manager of China for Thermo King, a U.S. company that provides temperature control solutions for transportation, did some calculations in an interview with China News Service: based on the calculation that each person receives 2 to 3 shots, the domestic demand for vaccines would be more than 2 billion doses; and based on the world's population, the demand would be even greater.

▲The US logistics company UPS urgently established a "refrigerator farm" in its warehouse to cope with the storage pressure of millions of doses of vaccines (Source: nytimes.com)

Liu Baolin believes that the current scale of COVID-19 vaccination is not very large, and the cold chain equipment on the market can still cope with it. However, if vaccination is liberalized on a large scale, issues such as the turnover rate of transportation and storage equipment need to be considered. In view of the current equipment conditions in various links in the country, relevant departments should conduct investigations and use big data technology to start planning and make appointments for vaccination from the vaccination link, and then feedback to the production and distribution links to form a reasonable turnover rate design, so that vaccination needs can be met.

If the cold chain equipment invested during the epidemic control period is to be used smoothly, it may need to be incorporated into a logistics system built by the state to achieve relatively centralized and higher calling efficiency.

In the vaccination process, my country has strict work procedures, such as the number of people that each vaccinator can vaccinate per day (to prevent mistakes due to work fatigue), the observation time limit for the vaccinated population, information entry and product traceability, etc. In other words, because the vaccination process takes a certain amount of time, the pressure on the production and distribution links will be relatively reduced.

"Deep cold" demand catalyzes cold chain technology breakthrough

According to the temperature and time requirements of the vaccine storage and transportation cold chain, there are currently various types of preservation boxes and other equipment on the market. These technologies mainly include mechanical refrigeration, dry ice, liquid nitrogen, etc., which can meet the requirements of 2℃-8℃, -20℃, -70℃ or even lower temperatures.

▲Dry ice can keep mRNA vaccines low in temperature

In Northeast my country and other regions, since the lowest outdoor temperature can reach -40℃, in order to prevent the vaccine from becoming ineffective at ultra-low temperatures, heating is required to bring the temperature to 2℃~8℃.

The suitable storage environment for inactivated vaccines is usually 2°C-8°C. In contrast, some international pharmaceutical companies have developed mRNA COVID-19 vaccines, which are less stable at room temperature and require ultra-low temperature storage conditions to preserve (if the temperature requirements are not met, some biological components in the vaccine will degrade). This type of vaccine has high requirements for storage and transportation, and usually requires a deep cold environment (such as -20°C or -70°C).

Although the current technologies of low-temperature refrigerators, cold storage and other equipment are relatively mature, and the use of mechanical refrigeration or liquid nitrogen can also ensure a stable environment of -70℃~-196℃, these low-temperature refrigerators are large in size and heavy in weight, which is not conducive to the long-distance transportation of vaccines.

"The deep-cold transportation of vaccines places high demands on cold chain equipment. Currently, many companies are actively developing related equipment," said Liu Baolin.

On the other hand, in the absence of sufficient ultra-cold cryogenic freezer facilities, large amounts of dry ice have become an alternative. Pfizer has developed a special constant temperature box that can store vaccines for 10 days using dry ice. Although it cannot maintain an environment below -70°C for a long time, it can basically meet the current short-distance transportation and use of vaccines.

▲Dry ice insulation box developed by Pfizer (Source: CNN)

However, the tricky thing is that dry ice is classified as "dangerous goods" in international cargo transportation. Lufthansa warned that dry ice would reduce the aircraft's ability to transport vaccines (the amount of dry ice that can be stored on board is limited, generally within 500 to 1,000 kilograms).

In addition, the infrastructure and health levels of some countries are relatively backward, and how to ensure the safe transportation and vaccination of vaccines is also a problem. For example, Toby Peters, a professor at the University of Birmingham in the UK, once pointed out that in some regions and countries, 30% to 40% of medical centers may not have electricity, and in some places, less than 10% of medical centers may have refrigerators that can function normally. To fully defeat the new crown epidemic, the world needs more diverse vaccine cold chain transportation technologies and solutions.

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Produced by: Beijing Science and Technology News | Science Plus Client

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