[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Immunology](https://durgical.com/en/immunology/) › [Vaccines](https://durgical.com/en/immunology/#a-vaccines) › The cold chain

[Immunology](https://durgical.com/en/immunology/) · [Vaccines](https://durgical.com/en/immunology/#a-vaccines)

# 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

## Key points

- Cold chain: 2 to 8 °C at all local levels.
- Freezing ruins aluminium-adjuvanted vaccines; heat and light mainly harm live ones.
- A damaged vaccine can look normal.
- After an excursion: do not use, set apart, report and document.

## 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.

## Memory aid

Neither ice nor sun: between 2 and 8 degrees, the vaccine keeps like a dessert in the fridge, never in the freezer or on the windowsill.

## 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.

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## Related

- [Vaccine types: live, inactivated, subunit, toxoid, mRNA, vector](https://durgical.com/en/immunology/vaccine-types-live-inactivated-subunit-toxoid-mrna-vector/)
- [Colombia's PAI schedule (which vaccines, at what age)](https://durgical.com/en/immunology/colombia-s-pai-schedule/)
- [Events after vaccination (ESAVI) and how they are reported](https://durgical.com/en/immunology/events-after-vaccination-and-how-they-are-reported/)

[← All of immunology](https://durgical.com/en/immunology/)

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](https://vacunacion.minsalud.gov.co/Vacunas/Paginas/almacenamiento-y-distribucion.aspx) (Ministerio de Salud y Protección Social de Colombia (PAI), 2026); [Chapter 5: Vaccine Storage and Handling | Pink Book | CDC](https://www.cdc.gov/pinkbook/hcp/table-of-contents/chapter-5-vaccine-storage-and-handling.html) (Centers for Disease Control and Prevention (CDC), 2021); [Chapter 1: Principles of Vaccination | Pink Book | CDC](https://www.cdc.gov/pinkbook/hcp/table-of-contents/chapter-1-principles-of-vaccination.html) (Centers for Disease Control and Prevention (CDC), 2021).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/immunology/the-cold-chain/