Here is the complete, detailed guide on the cold chain:
Vaccine Cold Chain - Complete Guide
What Is the Cold Chain?
The cold chain is a system of storage and transport of vaccines at low temperature - from the manufacturer to the actual vaccination site. It is necessary because vaccine failure occurs when strict temperature controls are not maintained. Once potency is lost, it cannot be regained or restored.
The cold chain must satisfy the "6 Rights" of supply chain:
Right vaccine → Right quantity → Right place → Right time → Right condition (no temperature breaks) → Right cost
India's Cold Chain Infrastructure (2026 Update)
India has one of the largest vaccine cold chains in the world:
| Parameter | Figure |
|---|
| Total cold chain points | ~30,000 |
| Ice-Lined Refrigerators (ILRs) + Deep Freezers | 1.06 lakh (1,06,000+) |
| Walk-in Coolers (WIC) + Walk-in Freezers (WIF) | 432 |
| Immunisation sessions conducted annually | 1.3 crore (13 million) |
| Span | National vaccine depots → Primary Health Centres |
Source: PIB, February 2026
Cold Chain Equipment - Classified
A. Storage Equipment
Electrical
| Equipment | Temp Range | Use / Level |
|---|
| Walk-in Freezer (WIF) | -15°C to -25°C | National/State/Regional stores; bulk OPV storage + ice pack preparation; has auto standby generator |
| Walk-in Cooler (WIC) | +2°C to +8°C | State/District; large quantity storage of all vaccines except OPV; sizes of 16.5, 32, 40 cubic meters |
| Ice-Lined Refrigerator (ILR) | +2°C to +8°C | District/PHC level; most important cold chain link; maintains temp even during 8-hour power cuts via ice bank lining |
| Deep Freezer (DF) | -15°C to -25°C | District/CHC level; OPV storage + freezing ice packs |
| Domestic Refrigerator | +2°C to +8°C | Sub-centre; limited use only |
Solar
| Equipment | How It Works |
|---|
| Solar Refrigerator (Battery Drive) | DC compressor charged by solar panels; two compartments: vaccine (+2 to +8°C) and freezer (up to -7°C) |
| Solar Refrigerator (Direct Drive) | Freezes a "phase change material" using solar energy; uses that ice bank to maintain cooling at night/cloudy days |
Solar equipment is critical for areas with unreliable power - expanding rapidly under UIP.
Non-electrical
- Cold boxes
- Vaccine carriers
B. Transportation Equipment
| Equipment | Use |
|---|
| Refrigerated Vaccine Van | Maintains temp during long-distance transport |
| Insulated Vaccine Van | Short-distance transport with ice packs |
| Cold Box | Carries 20-100 vials; maintains temp for 24+ hours with frozen ice packs; used for outreach/field sessions |
| Vaccine Carrier | Carries 16-20 vials; 4 frozen ice packs; for outreach sessions |
| Day Carrier | Carries 6-8 vials; 2 frozen ice packs; few hours use only for nearby sessions |
| Ice Packs | Filled with plain water (no salt); discarded if leaking |
Key rule: At sub-centre and village level, vaccines are NOT stored - they are supplied on the day of use only. Risk of cold chain failure is greatest at this level.
Temperature Sensitivity of Vaccines
Freeze-sensitive vaccines (must NOT go below 0°C)
These are destroyed by freezing - more dangerous than heat for these:
- Pentavalent (DPT+HepB+Hib)
- Hepatitis B
- IPV (fIPV)
- PCV
- Rotavirus
- HPV
- Td / TT / DT
- Influenza, Cholera
Heat-sensitive vaccines (Groups A-F, most to least sensitive)
| Group | Vaccines |
|---|
| A (most sensitive) | OPV |
| B | Influenza |
| C | IPV, JE (freeze-dried), MR (freeze-dried) |
| D | Cholera, Pentavalent, Hib (liquid), Rotavirus, Rubella |
| E | BCG, HPV, JE, Td/TT |
| F (least sensitive) | Hepatitis B, Hib (freeze-dried), Pneumococcal |
Light-sensitive vaccines
BCG, Measles, MR, MMR, Rubella - supplied in dark glass vials; keep in secondary packaging as long as possible.
ILR - The Most Important Cold Chain Link
The Ice-Lined Refrigerator is the cornerstone of the cold chain at PHC/district level:
- Operates on vapour compression (like a regular fridge)
- Has an ice-lined inner wall that maintains vaccine temperature for up to 8 hours during power cuts
- Basket-type design - vaccines stored in baskets, NOT against the walls
- Temperature must be checked and recorded twice daily (morning + end of session)
Open Vial Policy (OVP) - 2015
A key policy that reduces vaccine wastage - allows re-use of partially used multi-dose vials in subsequent sessions up to 28 days after opening, provided:
- Cold chain has been maintained (vaccine stored at +2°C to +8°C throughout)
- VVM (Vaccine Vial Monitor) has not passed the discard point
- Vial expiry date has not passed
- Vaccine septum has not been submerged in water
- No visible contamination or floating particles
Applies to: DPT, TT, Hepatitis B, OPV, Liquid Pentavalent, PCV
Does NOT apply to: BCG, Measles, MR, JE (reconstituted vaccines - must be discarded within 4 hours of opening)
Vaccine Vial Monitor (VVM)
A heat-sensitive label on each vial:
- The inner square is lighter than the outer circle = safe to use
- Inner square same colour or darker = discard, do not use
- Helps field workers make real-time discard decisions without a thermometer
eVIN - Digital Cold Chain Monitoring (Latest Update)
Electronic Vaccine Intelligence Network (eVIN) has been expanded pan-India across all States/UTs (as of 2026):
- IoT temperature sensors on every storage unit
- Real-time alerts if temperature goes out of range
- Tracks vaccine stock levels at each cold chain point
- Central dashboard for supply chain managers
- Proved critical during COVID-19 rollout
- Now being exported as a model to other countries (Lao PDR, Zambia)
Handling During Immunisation Session
- Check vials at start of session; discard if VVM has passed
- Keep freeze-sensitive vaccines (Pentavalent, IPV, PCV, Hep B) away from direct contact with frozen ice packs - place a layer of foam/card between them
- OPV can be placed directly against ice packs (freeze-stable)
- Reconstituted vaccines (BCG, MR): discard after 4 hours or at end of session, whichever is earlier
- Multi-dose opened vials with preservatives: OVP applies (up to 28 days) if conditions met
New Updates (2025-2026)
- eVIN expanded nationwide - all States/UTs now covered with real-time temperature + stock monitoring
- U-WIN integration with eVIN - demand-side and supply-side now digitally linked for the first time
- Model Immunisation Centres launched in UP, Bihar, Chandigarh, and Ladakh - upgraded cold chain + digital infrastructure as pilot hubs
- HPV vaccine cold chain set up pan-India for the February 2026 campaign (HPV is freeze-sensitive, Group E)
- A-VIN (Animal Vaccine Intelligence Network) - same eVIN framework now piloted in two states for animal vaccines, showing scalability of the model
Sources:
- Park's Textbook of Preventive and Social Medicine - "The Cold Chain," Cold Chain Equipment, Temperature Requirements sections (pp. 122-126)
- PIB India - Celebrating the Power of Vaccines, 2026
- UNDP India - A Decade of Digital Health, 2025