The cold chain !
- Topic
Vaccines are damaged by heat, light or freezing. The cold chain keeps them between 2 and 8 °C from the factory to the person's arm.
Updated 2026-11-01
What it is
The cold chain is the set of equipment, people and procedures that keep vaccines at the right temperature during storage, transport and administration. A vaccine kept out of range can lose potency without looking any different, and giving it creates a false sense of protection. In Colombia the PAI organizes it by levels, from the national warehouse to the vaccination post.
Key facts
- Vaccine refrigerator range: 2 to 8 °C.
- Vaccines with aluminium adjuvant (hepatitis B, toxoids, pertussis combinations) are ruined by freezing.
- Live vaccines (MMR, BCG, varicella, yellow fever) are especially sensitive to heat and light.
- Areas without grid power use prequalified solar refrigerators.
- Continuous monitoring with digital data loggers catches temperature excursions.
Step by step
- The manufacturer delivers the vaccine to the PAI national warehouse in Bogotá, which has cold rooms.
- The national level ships to departmental and district collection centres.
- These send to the municipalities in WHO-prequalified insulated boxes.
- The local level (hospitals, health centres and posts) stores vaccines in refrigerators at 2 to 8 °C.
- During the session, cool boxes with cold packs are used and the temperature is logged.
- The vaccine is given protected from light and heat, within the allowed time once opened.
Clinical notes
- After a temperature excursion: label the vaccine «do not use», set it apart without discarding it, alert the person in charge and ask the programme or manufacturer before deciding.
- A cold chain failure is a programmatic error and can explain disease in vaccinated people.
Test yourself
Think of the answer, then tap the question to see it.
Between what temperatures are vaccines kept in the vaccination post refrigerator?
Between 2 and 8 °C.
Which group of vaccines is typically damaged by freezing?
Those with aluminium adjuvant, such as hepatitis B and those containing tetanus and diphtheria toxoids.
What is done with a batch exposed to an out-of-range temperature?
It is labelled «do not use», set apart without discarding it, reported to the person in charge, and the programme or manufacturer is consulted, documenting everything.
Related
- Vaccine types: live, inactivated, subunit, toxoid, mRNA, vector
- Colombia's PAI schedule (which vaccines, at what age)
- Events after vaccination (ESAVI) and how they are reported
Educational content on the immune system; not a treatment or individual vaccination guide and no substitute for a health professional's advice. No doses are given.
Sources: La cadena de frío del Programa Ampliado de Inmunizaciones - PAI (Ministerio de Salud y Protección Social de Colombia (PAI), 2026); Chapter 5: Vaccine Storage and Handling | Pink Book | CDC (Centers for Disease Control and Prevention (CDC), 2021); Chapter 1: Principles of Vaccination | Pink Book | CDC (Centers for Disease Control and Prevention (CDC), 2021).
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Representative model, for educational purposes only.