What are the differences between recombinant vaccines and inactivated vaccines?

Both recombinant vaccines and inactivated vaccines are common vaccine types, with key differences between them in terms of preparation principles, immunogenicity, safety, vaccination schedules, and storage conditions. A detailed comparison is as follows:

1. Preparation principle: Recombinant vaccines use genetic engineering techniques to extract specific antigen genes from pathogens, insert them into cells or microorganisms for antigen protein expression, and then purify the expressed proteins to produce vaccines. In contrast, inactivated vaccines use physical or chemical methods to completely inactivate live pathogens while preserving their immunogenicity.

2. Immunogenicity: Recombinant vaccines contain only specific antigen components, offering highly targeted immunity, but often require adjuvants to enhance immune responses. Inactivated vaccines retain the complete structure of the pathogen, providing broader immunogenicity that can stimulate both humoral and cellular immunity without the need for additional adjuvants.

3. Safety: Recombinant vaccines do not contain pathogen nucleic acids and lack replication ability, so they cannot cause infection. They are associated with lower rates of adverse reactions, which are typically mild (e.g., local redness and swelling). Although the pathogens in inactivated vaccines are no longer active, trace impurities may remain, leading to mild reactions such as low-grade fever or fatigue in some individuals, though these are generally transient and minor.

4. Vaccination schedule: Due to relatively shorter duration of immunity, recombinant vaccines often require multiple doses to maintain adequate antibody levels, with the exact number depending on the specific vaccine. Inactivated vaccines tend to induce more durable immune memory; most provide effective protection after 2–3 doses, with longer intervals required between booster shots.

5. Storage conditions: Some recombinant vaccines are based on protein structures and are temperature-sensitive, requiring refrigeration at 2–8°C, although certain formulations may tolerate short-term room temperature storage. Inactivated vaccines are more stable and can be stored long-term at 2–8°C, with relatively less stringent temperature control requirements during transportation.

Both vaccine types have their respective advantages. The choice of vaccine should be based on pathogen characteristics, recipient age, and health status, following standardized administration procedures. After vaccination, individuals should remain on-site for observation for 30 minutes.