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Cold ChainDr Ravindra Singh Department of Community medicine S N Medical College, Agra, U P
Cold Chain The Cold Chain is a system of storing and transporting vaccines at recommended temperatures from the point of manufacture to the point of use.
Vaccine Damage The physical appearance of the vaccine may remain unchanged even after it is damaged. However, the loss of potency due to either exposure to heat or cold is permanent and can not be regained.
Checking for heat damageThe Vaccine Vial Monitor (VVM): A VVM is a label containing a heatsensitive material which is placed on a vaccine vial to register cumulative heat exposure over time.
The combined effects of time and temperature cause the inner square of the VVM to darken gradually and irreversibly. Before opening a vial, check the status of the VVM.
Does a VVM measure vaccine potency ? No, the VVM does not directly measure vaccine potency It gives information about the main factor that affects potency: heat exposure over a period of time.
The physical appearance of the vaccine may remain unchanged even after it is damaged. However, the loss of potency due to either exposure to heat or cold is permanent and cannot be regained. The VVM does not, however measure exposure to freezing that contributes to the degradation of freeze-sensitive vaccines.
FREEZE DAMAGE Hepatitis B, DPT, DT, and TT vaccines lose their potency if frozen. Freezing dissociates the antigen from the adjuvant alum thus interfering with the immunogenicity of the vaccine. Moreover, the risk of adverse events following immunization, such as sterile abscesses, may increase. Therefore, always store 'T-series' vaccines (DPT, DT, TT) and Hep.B vaccine between +2C and +8C.
FREEZE DAMAGE Diluents must be cooled for at least 24 hours before use to ensure that vaccines and diluents are at +2C and +8C when being reconstituted. If the vials are found to be frozen or contain floccules, discard the vials. Conduct the shake test if you suspect that vials could have been frozen.
Shake Test Step 1- prepare a frozen control sample by freezing the vial until the contents are solid. Step 2- choose a test sample. Step 3- shake the control & test sample for 10-15 second. Step 4- allow to rest both vials by placing them on a table. Step 5- compare sedimentation rate of both vials, if the sedimentation rate is similar the test vial has probably been damaged by freezing and should not be used.
REMEMBER Do not keep in the cold chain, any vials that are expired, frozen or with VVMs beyond the discard point, as they may be confused with those containing potent vaccines. Keep them in the red bag for disinfection and disposal.
Cold Chain Equipment Cold chain equipment, both electrical and non-electrical, is used for storing vaccines and/or transporting them at appropriate temperatures.
Equipments Walk in Freezers (WIF) -They are located at state, regional & district head quarters - Meant to store OPV in bulk & to freeze ice packs - Maintain temperature -20C. Walk in cold rooms (WIC)- They are located at regional level. - Meant to store vaccines upto 3months & serve 4-5 Districts - Maintain temperature +2 to +8C.
Summary of cold chain equipmentEquipment Electrical Deep freezer Large(300 ltr) Temperature-15 to -25C
Storage Capacity200 ice packs or OPV stocks for 3 month(1,20,0001,80,000) BCG, DPT, TT, Measles, Hep. B stock for 3 months (60,000 doses) 100 ice packs BCG, DPT, TT, Measles, Hep. B stock for 1 month(25,000 doses)
ILR Large (300/240ltr)
+2 to + 8C
Deep freezer small (140ltr)
-15 to -25C +2 to +8C
ILR Small(140 ltr)
Summary of cold chain equipmentEquipment Nonelectrical Cold Box large (20 ltr) +2 to + 8C All vaccines are stored for transport or power failure(72-96 ice packs) All vaccines are stored for transport or power failure(36 ice packs) All vaccines are carried for 12 hrs (4 ice packs & 20 vials) Temperature Storage Capacity
Cold Box small (5ltr)
+2 to + 8C
Vaccine Carrier (1.7 ltr) +2 to + 8C
Keep all Electrical Cold Chain equipment At least 10 cm away from walls Protected from rain or flooding and away from direct sunlight Level and on wooden blocks Properly connected to one Voltage stabilizer per equipment Locked and keys accessible to designated personnel
DEEP FREEZERS (DFs)
Maintain a cabinet temperature between -15C to -25C Store OPV and prepare ice packs at the district level. At the PHC level, Deep freezers are used only for preparation of ice packs and are not to be used for storing UIP vaccines. About 20-25 icepacks can be prepared by a 140 Liter DF in 24 hours with at least 8 hours of continuous electricity supply.
ICE LINED REFRIGERATORS (ILRs): Maintain a cabinet temperature between +2C to +8C used to store all UIP vaccines at the PHC level. ILRs are lined with ice packs filled with water which freezes and keeps the internal temperature at a safe level despite electricity failure. ILRs can keep vaccine safe with as little as 8 hours continuous electricity supply in a 24-hour period. Since ILRs are top-opening, they can hold the cold air inside better than a front-opening refrigerator.
VACCINE VANS: Are insulated vans used for transporting the vaccines in bulk. The vaccines should be transported to the last cold storage point only through vaccine vans. Vaccines should be transported only in Cold boxes with the desired number of conditioned ice packs.
COLD BOXES Are insulated boxes, used for transportation and emergency storage of vaccines and icepacks. Place conditioned ice packs at the bottom and sides of the cold box before loading the vaccines in cartons or polythene bags.
COLD BOXES Always keep a thermometer inside the cold box. Do not place DPT, DT, Hep B and TT vials in direct contact with conditioned ice packs. Do not place weights or other cold boxes on the lid since it will damage the rubber
VACCINE CARRIERS With 4 conditioned ice packs, maintain the inside temperature between +2C to +8C for 12 hours, if not opened frequently. They are used for carrying vaccines (16-20 vials) and diluents from PHCs to session sites. Never use day carriers which contain 2 ice packs for routine immunization. Never use any screw driver or any other sharp shaft to open the lid of vaccine carrier.
VACCINE CARRIERS Ensure the return of unused vaccine vials from session sites to the PHC on the same day in the cold chain through alternate vaccine delivery. Keep a unused vaccines that can be used in subsequent sessions. Discard vaccines that have been returned unopened. Do not keep any used vials in the cold chain.
Correct packing of the vaccine carrier1. Prepare ice packs for freezing-Fill ice pack with water to mark. -DO NOT ADD SALT TO WATER -Fit the stopper & screw on the cap tightly -Make sure the ice pack does not leak. -Wipe the ice pack dry & place in the deep freezer. 2. Condition frozen Ice pack- Place frozen ice packs in the open till they sweat (some condensation or droplets of water). - Check if an ice pack has been conditioned by shaking it & listening for water.
3. Pack the vaccine carrier- Place four conditioned ice pack against the sides of the carrier. - Place the plastic bag containing all vaccines & diluents in the centre of the carrier.4. Remember to-collect vaccines in the carrier on the session day (vaccine carriers not store vaccines effectively beyond 12 hrs.). -Do not drop or sit on vaccine carrier. -Do not leave in sunlight, keep in shade. -Do not leave the lid open once packed.
ICE-PACKS Are plastic containers filled with water. These are frozen in the deep freezer and when placed in nonelectrical cold chain equipment such as vaccine carriers and cold boxes, help increase the holdover time. The most common cause of exposure of freeze sensitive vaccines to freezing temperatures is the failure to correctly condition ice packs prior to transport.
Condition Icepacks Conditioning prevents freezing of freezesensitive vaccines. When icepacks are removed from a freezer, at say - 25C, they need to be kept at room temperature for long enough to allow the temperature of the ice at the core of the icepack to rise to 0C. This process is called conditioning.
An ice pack is adequately conditioned as soon as beads of water cover its surface and the sound of water is heard on shaking it.
Immunization servicesStrategy1. Routine immunizationa. At health centre b. In field- at fixed day & fixed site or place Health centre will fix the periodicity depending upon the no. of children/ doses i.e. daily or on alternate day, while at village level/ outreach visits, it is once in a month by health workers (ANM) 2. Special immunization campaigns- IPPI , NIDs
National Immunization Schedule For Infants At birth At 6 weeks -BCG, OPV (zero dose) -BCG (if not given at birth) DPT-1,OPV-1,Hep B-1* -DPT-2,OPV-2,Hep B-2* -DPT-3,OPV-3,Hep B-3* -Measles, Vit A^ -DPT & OPV booster -DPT(2doses if not given earlier at an interval of 1month) -TT
At 10 weeks At 14 weeks At 9 months At 16-24 months At 5-6 Years
At 10 & 16 years *- In some disricts ^- in every 6 month till 5years of age
National Immunization Schedule For pregnant femalesEarly in pregnancy -TT- 1/booster (during 1st visit) One month after TT-1 - TT-2
Doses & site/route 1. BCG - 0.1ml given I/D 2. OPV - 2drops given oral 3. DPT - 0.5 ml given I/M 4. Hep B - 0.5 ml given I/M 5. Measles -0.5ml given S/C 6. Vit A - 1yr 1 spoon 7. TT - 0.5 ml given I/M
How to hold a immunization session
In the field (outreach) - Sessions should be held re