Freeze drying technology plays a crucial role in vaccine research and production, directly determining the stability, accessibility, and vaccination coverage of vaccines.

Freeze drying technology is the core technology for vaccine research and production, which converts liquid vaccines into solid powders through low-temperature dehydration to solve their thermal instability problems. This technology can significantly improve the thermal stability of vaccines, allowing many vaccines that originally required strict cold chain (2-8 ° C) storage and transportation (such as attenuated live vaccines for measles, chickenpox, etc.) to be stored at room temperature for a long time, greatly expanding the accessibility of vaccines in remote areas.

1、 Core advantage: Why do vaccines have to be freeze-dried?

1. Realize room temperature stability and eliminate "cold chain dependence"

Most traditional liquid vaccines, especially attenuated live vaccines, are extremely sensitive to temperature and must be stored and transported in a strict 2-8 ° C cold chain. This is a huge challenge in remote areas with weak infrastructure, known as“oneThe kilometer problem.

By freeze-drying, remove the moisture from the vaccine and turn it into a solid powder. The metabolism and chemical decomposition of viruses, bacteria, or protein active ingredients in a dry state almost cease, allowing them to remain stable for a long time (usually up to 2-3 years) at room temperature (even up to 40 ° C).

Greatly reducing storage and transportation costs, enabling vaccines to reach remote corners, is the key to the success of immunization programs such as COVAX.

2. Significantly extend shelf life

Freeze dried formulations effectively eliminate the risks of hydrolysis, oxidation, and microbial growth caused by moisture by converting the product into a solid powder, significantly extending its shelf life compared to liquid formulations and reducing losses and waste caused by spoilage or expiration during storage.

3. Improve the flexibility of dosage forms

Freeze dried powder can be conveniently divided into single dose penicillin bottles, which can be reconstituted (redissolved) with a specialized diluent before use to ensure accurate dosage and sterile operation.

2、 Application process: The entire chain from research and development to production

This process is a systematic engineering that transforms liquid unstable vaccines into solid stable products through scientific formulation and precision controlled freeze-drying technology. Its core value lies in breaking through the limitations of temperature on the lifecycle of vaccines.

1. Preparation of original solution and optimization of prescription

In the research and development phase, the core task is to determine the "freeze-drying protectant prescription". Scientists will mix the active ingredients of vaccines (such as viruses, proteins, or mRNA) with a series of stabilizers and protectants (such as sucrose, trehalose, amino acids) to form a stable stock solution. The goal here is to screen formulas that can protect antigen structures like "molecular armor" during subsequent freeze-drying processes.

2. Aseptic processing and filling

In large-scale production, the raw material needs to undergo sterile filtration to ensure no microbial contamination. Then, in a highly clean environment, the quantitative liquid is accurately dispensed into sterile penicillin bottles through an automated filling line, and half capped (with reserved water vapor sublimation channels).

3. Core Process - Freeze Drying

This is the most critical conversion step, which is carried out in stages within the freeze dryer:

Pre freezing:Quickly cool the filled product to below -40 ℃ to solidify the solution and form a uniform ice crystal network, laying the foundation for the final porous structure.

One drying (sublimation drying):Slowly heat in a highly vacuum environment to allow ice crystals to sublime directly into water vapor without passing through the liquid state and be captured by a cold trap. At this stage, the vast majority of free water is removed.

Secondary drying (analytical drying):Further increase the temperature and maintain high vacuum to remove residual moisture tightly bound to the product, resulting in a final product moisture content typically below 3%.

The Mercury series of Furuijie in-situ freeze-drying machine can be used for exploring freeze-drying processes

4. Sealing and sealing

After drying, under the protection of vacuum or inert gas (such as nitrogen), the freeze-drying box is automatically filled with full pressure plug, and finally sealed with an aluminum cover to form a stable system isolated from the outside.

3、 Typical examples of vaccine applications

▶01. Vaccine type:Attenuated live vaccine

Freeze drying application representative:Measles, mumps, rubella vaccine (MMR combined vaccine), chickenpox vaccine, yellow fever vaccine

Key role:crucial. Freeze drying is a practical method for maintaining the long-term activity of attenuated live viruses, allowing them to be distributed at room temperature.

▶02. Vaccine type:Virus vector vaccine

Freeze drying application representative:AstraZeneca/Johnson&Johnsonvaccines(Adenovirus vector)

Key role:Freeze drying can improve the thermal stability of adenovirus vectors and simplify the supply chain.

▶03. Vaccine type:Recombinant protein vaccine

Freeze drying application representative:New generation HPV vaccine, hepatitis B vaccine

Key role:Although the protein itself is relatively stable, freeze-drying can further improve its long-term stability and develop injectable formulations (such as oral freeze-dried powder, microneedle patches).

▶04. Vaccine type:mRNA vaccine

Freeze drying application representative:Multiple companies are currently developing (such as CureVac, Gennova)

Key role:This isfrontierThe application. Freeze drying is a solution to the extreme instability of mRNA molecules and the need for ultra-low temperature (-70 ° C) storage, which is expected to achieve room temperature storage of mRNA vaccines.

Freeze drying technology has surpassed the simple "drying" process and become a strategic technology for ensuring efficacy and expanding accessibility in vaccine research and development. It is not only a stabilizer for existing vaccines, but also a key enabler for the realization and popularization of future innovative vaccines such as mRNA vaccines and needle free vaccination. With the development of technology, its efficiency will be further improved, continuing to safeguard public health.