a) Cold chain

b) Components required to maintain the cold chain

1. Personnel
   • Trained cold-chain handler or vaccine storekeeper
   • A designated person responsible for temperature monitoring, stock arrangement, maintenance, and emergency action.
2. Cold-chain equipment for storage
   • Walk-in cooler (WIC)
   • Walk-in freezer (WIF)
   • Ice-lined refrigerator (ILR)
   • Deep freezer (DF)
   • Solar refrigerator or vaccine refrigerator/freezer
   • Domestic refrigerator, where appropriate and with reliable electricity.
3. Equipment for transport
   • Refrigerated vans
   • Cold boxes
   • Vaccine carriers
   • Day carriers
   • Ice packs or coolant packs.
4. Temperature-monitoring devices
   • Thermometer or digital thermometer
   • Electronic temperature logger/data logger
   • Continuous temperature recorder and alarm system
   • Vaccine vial monitor (VVM)
   • Freeze indicator, where used.
5. Power supply and backup
   • Reliable electricity supply
   • Voltage stabilizer
   • Generator or alternative storage arrangement
   • Solar-powered system in areas with unreliable electricity.
6. Maintenance, records, and procedures
   • Temperature logbook
   • Stock register and expiry monitoring
   • Preventive maintenance and repair system
   • Written contingency plan for equipment or power failure.

c) Points to be kept in mind for maintaining the cold chain

1. Maintain the recommended temperature
   • Keep routine vaccines generally between +2°C and +8°C.
   • Store OPV in a deep freezer at higher levels as per programme guidance.
   • Never permit freezing of freeze-sensitive vaccines.
2. Know the sensitivity of every vaccine
   • Heat-sensitive vaccines require protection from high temperature.
   • Freeze-sensitive vaccines include DPT-containing vaccines, tetanus toxoid-containing vaccines, hepatitis B, pentavalent vaccine, IPV, HPV, and pneumococcal vaccine.
   • BCG, measles, MR/MMR, rubella and similar vaccines must be protected from sunlight and strong artificial light.
3. Monitor and record temperature twice daily
   • Check at the beginning and end of the working day.
   • Record the temperature in the logbook.
   • Investigate and act immediately if the temperature goes outside the permitted range. WHO advises continuous or electronic temperature monitoring where feasible, especially to identify harmful freezing events. WHO temperature-monitoring guidance
4. Keep a responsible trained person
   • One staff member should be responsible for the cold chain, with a trained substitute during absence.
   • All staff should know what to do during a temperature excursion.
5. Arrange vaccines correctly in ILR
   • Keep vaccines in baskets, not directly on the floor or against the walls.
   • Keep freeze-sensitive vaccines in the upper, warmer part of the ILR.
   • Keep adequate space between cartons for circulation of cold air.
   • Do not overfill the refrigerator.
6. Avoid frequent opening of lids and doors
   • Keep ILR/deep freezer closed and locked.
   • Open only when necessary and close immediately.
   • Frequent opening shortens hold-over time during power failure.
7. Use vaccine carriers and cold boxes correctly
   • Transport vaccines in correctly packed vaccine carriers/cold boxes using properly prepared ice or coolant packs.
   • During sessions, keep vaccines in the carrier and use a foam pad at the top, if available.
   • Return unused eligible vaccines to the cold-chain point on the same day.
8. Keep equipment properly installed and maintained
   • Place equipment in a cool, well-ventilated room, away from direct sunlight.
   • Keep it level and at least 10 cm away from the wall.
   • Use a voltage stabilizer.
   • Defrost at appropriate intervals and arrange preventive maintenance.
9. Prepare for power or equipment failure
   • Know the hold-over time of each unit.
   • Keep ice packs ready.
   • Shift vaccines promptly to cold boxes and then to an alternate functioning cold-chain point if failure continues.
   • Keep backup power or solar systems where available.
10. Do not misuse cold-chain equipment

• Do not store food, drinking water, laboratory samples, or other drugs in vaccine refrigerators/freezers.
• Do not keep expired vaccines.
• Do not store vaccines beyond recommended stock levels.
• Do not use a vaccine-storage deep freezer for freezing ice packs, as this can raise the temperature and damage stored vaccine.

1. Follow stock management

• Use FEFO: first expiry, first out.
• Keep short-expiry vaccines in front.
• Check VVM status, expiry date, vial condition, and temperature records before use.

1. Handle reconstituted vaccines carefully

• Reconstituted BCG, measles, and rotavirus vaccines should be kept at +2°C to +8°C and discarded within the permitted session time, generally 4 hours.
• Reconstituted JE vaccine should be discarded earlier according to programme guidance.

Cold Chain

a) Definition of cold chain

b) Components required to maintain the cold chain

1. Trained personnel

• Receiving and checking vaccines.
• Correct storage and arrangement of vaccines.
• Recording temperature.
• Maintaining stock and expiry records.
• Monitoring VVM and freeze exposure where applicable.
• Packing vaccine carriers correctly for outreach sessions.
• Taking prompt action during power failure or equipment breakdown.
• Ensuring preventive maintenance of equipment.

2. Storage equipment

A. Walk-in freezer (WIF)

• Used at national, state, regional, or large vaccine stores.
• Maintains temperature at about -15°C to -25°C.
• Used for bulk storage of OPV at appropriate levels and for freezing ice packs.

B. Walk-in cooler (WIC)

• Used for large-scale storage of routine vaccines.
• Maintains +2°C to +8°C.
• Usually available at government medical stores, state, regional, and selected district vaccine stores.

C. Deep freezer (DF)

• Maintains temperature between -15°C and -25°C.
• Used for OPV storage at district level and above, as per programme guidance.
• Also used to freeze ice packs at the appropriate level.
• A deep freezer used for vaccine storage should not simultaneously be used to freeze ice packs, as this may raise cabinet temperature.

D. Ice-lined refrigerator (ILR)

• The most important storage equipment at district, PHC, and sub-district levels.
• Maintains temperature between +2°C and +8°C.
• Ice lining around the cabinet walls keeps the temperature safe for some time during power failure.
• It is top-opening, which prevents rapid loss of cold air.

E. Solar refrigerator or vaccine refrigerator/freezer

• Used in areas with unreliable electricity supply.
• May be battery-driven or direct-drive solar equipment.
• Maintains vaccine storage temperature at +2°C to +8°C.

F. Domestic refrigerator

• May be used in private clinics or nursing homes if a reliable continuous power supply and temperature monitoring are ensured.
• Has less storage capacity and less hold-over time than an ILR.

3. Transport equipment

A. Refrigerated vans

B. Cold boxes

• Insulated boxes used for transporting larger quantities of vaccines.
• Used during vaccine distribution, power failures, or transfer to another storage point.

C. Vaccine carriers

• Smaller insulated containers used to carry vaccines to outreach or immunization sessions.
• Packed with properly prepared ice packs or coolant packs.
• A foam pad may be placed over vaccines during the session to reduce heat exposure.

D. Day carriers

• Used for carrying a small number of vaccine vials to a nearby session.
• Used only for a few hours.

E. Ice packs/coolant packs

• Maintain low temperature in cold boxes and vaccine carriers.
• Water should be filled only to the marked level.
• Leaking ice packs must be discarded.

4. Temperature-monitoring devices

• Dial thermometer
• Digital thermometer
• Electronic temperature logger/data logger
• Continuous temperature recorder
• Alarm system
• Vaccine vial monitor (VVM)
• Freeze indicator or freeze tag, where available
• Remote temperature-monitoring system at larger stores

5. Power supply and backup arrangements

• Continuous electricity supply
• Voltage stabilizer
• Generator set at higher-level stores
• Solar-powered refrigeration in remote areas
• Alternate vaccine storage point
• Cold boxes with ice packs for emergencies

6. Records, maintenance, and stock-control system

• Daily temperature logbook
• Vaccine stock register
• Vaccine arrival and issue register
• Expiry-date record
• Equipment maintenance record
• Contingency plan for power failure/equipment failure
• First-expiry-first-out (FEFO) stock arrangement

c) Points to be kept in mind while maintaining the cold chain

1. Maintain the correct storage temperature

• Store each vaccine at the temperature recommended by the national immunization programme and manufacturer.
• For routine vaccine storage, maintain +2°C to +8°C in ILR/WIC.
• Use deep freezers/WIF only for vaccines and purposes requiring frozen storage.
• Do not allow any vaccine to be exposed to temperatures outside its permitted range.

2. Protect vaccines from heat

• Avoid leaving vaccines outside the refrigerator.
• Do not expose vaccine carriers or cold boxes to direct sun.
• Keep vaccine carriers closed during immunization sessions.
• Return unused vaccines to the cold-chain point promptly after the session.
• Check the VVM before using a vaccine vial.

3. Prevent freezing of freeze-sensitive vaccines

• DPT/DTwP-containing vaccines
• Pentavalent vaccine
• Hepatitis B vaccine
• Tetanus toxoid, Td, and TT-containing vaccines
• IPV
• HPV vaccine
• Pneumococcal vaccine
• Liquid Hib vaccine

• Never place these vaccines directly against ice packs, freezer plates, or the bottom/walls of an ILR.
• Store freeze-sensitive vaccines in the upper part of the ILR basket, where the temperature is relatively warmer.
• Condition ice packs when required before packing vaccine carriers, as per programme instructions.
• Use a freeze indicator or shake test according to local protocol when freezing is suspected.

4. Protect light-sensitive vaccines

• BCG
• Measles vaccine
• MR/MMR vaccine
• Rubella vaccine

• In their original secondary packaging as long as possible.
• Away from direct sunlight.
• Inside the vaccine carrier during sessions except when being used.

5. Monitor and record temperature regularly

• Check and record refrigerator temperature at least twice daily, usually in the morning and at the end of the working day.
• Check temperature before starting an immunization session.
• Maintain a temperature chart or logbook.
• Review records regularly to identify recurring faults.
• Act immediately if temperature is outside the recommended range.

6. Keep vaccines arranged correctly in the ILR

• Keep vaccines in the baskets supplied with the ILR.
• Do not keep vaccine vials directly on the floor of the ILR.
• Do not keep vials touching the wall or ice lining.
• Keep adequate space between vaccine boxes for circulation of cold air.
• Arrange vaccines according to temperature sensitivity.
• Keep diluent with the corresponding vaccine where required, at the recommended temperature.
• Keep vaccines with earlier expiry dates in front.

7. Follow FEFO stock management

• Check expiry date before issuing or using any vaccine.
• Place short-expiry vaccine stock in front.
• Do not use expired vaccines.
• Avoid overstocking at peripheral facilities.
• Maintain stock records and reconcile physical stock with registers.

8. Use equipment correctly

• Keep the refrigerator/freezer in a cool, well-ventilated room.
• Keep it away from direct sunlight.
• Maintain at least about 10 cm distance from the wall.
• Keep the unit level.
• Use a voltage stabilizer.
• Keep the lid/door closed except when necessary.
• Defrost equipment periodically and safely.
• Ensure regular servicing and preventive maintenance.

• Store food, drinking water, laboratory specimens, or other medicines in vaccine equipment.
• Put objects on top of refrigerators/freezers.
• Open the lid/door frequently.
• Keep expired vaccines in the cold chain.
• Store vaccines directly on the refrigerator floor.
• Mix vaccine storage with non-vaccine items.

9. Ensure correct use of cold boxes and vaccine carriers

• Use only correctly prepared ice packs or coolant packs.
• Pack vaccines according to their heat/freezing sensitivity.
• Keep freeze-sensitive vaccines away from direct contact with frozen ice packs.
• Close the lid properly.
• Do not open the carrier repeatedly during the session.
• Use a foam pad on top of vaccine vials if available.
• Carry only the required quantity of vaccines for the session.
• Return unused eligible vaccines in the cold chain on the same day.

10. Be prepared for power failure or equipment breakdown

• Know the hold-over time of each equipment.
• Keep the ILR/freezer lid closed during a power failure.
• Do not open equipment unnecessarily.
• If the failure is prolonged, transfer vaccines to a cold box with ice packs.
• Shift vaccines promptly to an alternate functioning cold-chain point.
• Inform the supervisor and document the incident.
• Check temperature records and assess vaccine usability before further use.

11. Handle reconstituted vaccines properly

• Reconstituted vaccines must be kept at +2°C to +8°C during the immunization session.
• Note the time of reconstitution on the vial.
• Discard according to the applicable programme policy and manufacturer instructions.
• Under common UIP guidance, reconstituted BCG, measles, and rotavirus vaccines should not be kept beyond 4 hours; reconstituted JE vaccine has a shorter permissible duration.

12. Train all staff and conduct supervision

• Every health worker should know the importance of the cold chain.
• Staff must know correct vaccine placement, carrier packing, temperature recording, and action during a cold-chain break.
• Regular supervision, maintenance, and review of temperature records are necessary.

Conclusion