Statistical analysis

Data were entered and analyzed using Epi Info v 3.5.1. Simple proportions were calculated.

Observations of ILR and deep freezer

A separate voltage stabilizer should be attached each to deep freezer and ILR, except in emergency, when one stabilizer per two small equipment is acceptable.[1] The function of the voltage stabilizer is to monitor the range of fluctuations in the main voltage of 90-280 V and maintain voltage in a required range of 220 + 10 V.[1] Stabilizer protects the cold chain equipment against voltage fluctuations and is an essential pre-requisite.[1] The present study claimed that a separate voltage stabilizer was attached each to deep freezer and ILR in only 15% of the health centers. A shortage of voltage stabilizers was also reported in several other studies.[11,12,13] Medical Officer of the respective UHCs should ensure adequate supply and maintenance of voltage stabilizer and report to higher authority in case scarcity persists.

Deep freezer and ILR should be placed in such a way in the room that they are not exposed to sunlight any time during the day.[1] Exposure to sunlight will lead to increase in core temperature of the cold chain equipment, which would break the cold chain by causing an increase in the temperature of the vaccines in ILR and ice packs would not be prepared in deep freezer. The present study stated that deep freezers were exposed to sunlight in 2 (10%) health centers. This finding was similar to a study by Sachdeva, et al. which reported that the cold chain equipment were kept away from sunlight in all the health centers.[12]

The temperatures in the ILR and deep freezer must be monitored twice daily.[1] A break in the cold chain is indicated if temperature rises above +8°C or falls below +2°C in the ILR; and above −15°C in the deep freezer.[1] The ILR and deep freezers each should have a separate thermometer and temperature record book.[1] It was refreshing to find that in our study, temperature was being recorded twice a day for both deep freezer and ILR in all the health centers in separate temperature record books. This was more than what Mallik, et al. (60%) and Sachdeva, et al. (71.87%) found in their studies.[12,13] Also, in the present study, working separate thermometers were found in deep freezer in 95% health centers and in ILR in all the health centers.

The temperature in the ILR/freezer can rise if there is a thick layer of ice around the freezer or along the walls and bottom of ILRs.[1] It is therefore necessary to defrost them periodically. This should be done if the ice in the freezer is >5 mm thick.[1] The present study showed that information regarding defrosting of deep freezers and ILRs was recorded on the temperature-record register in only half of the health centers. Thickness of ice on the side walls was >5 mm in the deep freezers and ILRs of half of the health centers. This was more than that shown by Sachdeva, et al. (37.5%), though they kept the cut-off for thickness >6 mm.[12] This suggests lack of regular defrosting by the cold chain handlers, which need to be improved and monitored subsequently by the Medical Officer of the respective UHC.

Ice packs should be stacked on the floor of the deep freezer horizontally (not flat) on its edge by keeping 1-2 mm space from each other for air circulation, in a criss-cross manner.[1] Yet, in our study, we found this in only one-third (35%) of the health centers. This was probably due to the increased demand of ice packs in health centers, especially during Sub-National Immunization Day (SNID) rounds, which are frequently conducted in urban areas of Surat city. The requirement for a large number of ice packs can be easily met with proper planning like transferring around 50 ice packs into a large cold box. Fifty more ice packs can be frozen in two days and continuing the procedure till the required number of ice packs are frozen.

Deep freezers should be used to prepare and store ice packs only; UIP vaccines should not be stored in it.[14] In spite of these guidelines, in our study, we found water bottles kept inside deep freezer in 2 (10%) health centers. It is customary, not to keep other drugs and vaccines not used in UIP, in ILR.[1,14] In our study, at 2 (10%) health centers, things other than vaccines/diluents, like empty water bottles, were kept inside the ILR. This was much less than what Sachdeva, et al. claimed in their study (53.12%).[12]

Vaccines lose their potency due to exposure to excessive heat or excessive cold. OPV and measles vaccines can be kept at bottom of the basket while BCG, DPT, DT and TT vaccines should be kept in upper part of the baskets.[1] In our study, we found that the vaccines were arranged accordingly in more than two-third of the health centers. This was similar to what Sachdeva, et al. stated in their study that heat-sensitive vaccines were stored correctly in all, while, freeze-sensitive vaccines were stored correctly in 62.5% health facilities only.[12] Vaccinators need to understand the importance of this arrangement, as impotent vaccines give a false sense of security against diseases, which a child would contract later on despite the vaccination.

Observations related to alternatives to cold chain failure

The present study found that emergency contact number was written nearby in the same room in only 3 (15%) health centers. Mallik, et al. argued in their study that no organization maintained a chart in case of cold chain failure.[13] Samant, et al. showed generator facility in 65% of PHCs.[15] This is in contrast to our study, where we found 30% UHCs had either a working inverter or a generator. Though, an alternate working refrigerator was available in just less than two-thirds of the health centers. The cold chain is dependent on electrically operated machines on which one cannot depend completely. Alternative storage locations will have to be identified in advance.[1] Suitable posters should be designed and pasted on machines with clear instructions in local languages on how to handle such emergency situations, especially during electricity failure.[1] It would be prudent to identify more than one alternative at each UHC for tackling the situation.[1]

Observations of vaccination sessions

On observing the vaccination sessions (n = 20), we found that the vaccinators were reading VVM at the time of vaccination at 13 (65%) health centers. The time of reconstitution was noted on the vaccine vial by the vaccinator at 15 (75%) health centers. The reconstituted vaccine was discarded after the recommended time limits in 19 (95%) health centers. Reconstituted BCG and measles vaccines should not be used beyond 4 hours from the time of its reconstitution.[1] This increases the chances of AEFIs (Adverse Effect Following Immunization).[1] If not utilized completely, these reconstituted vaccines should be discarded within 4 hours in the case of BCG and measles.[1]

Knowledge of vaccinators

It was good to see that three-fourth of the vaccinators knew the definition of cold chain exactly in its stated form, while one-fourth of the vaccinators knew the concept behind it suggesting that they were aware of cold chain. Most of the vaccinators knew the full form of VVM and stages of VVM correctly, suggesting that VVM is now a matter of common knowledge for the vaccinators. Thakur, et al. also highlighted similar results with 94.4% staff members being aware that VVM is present on vaccine itself and 71.7% knowing how to read it.[4] Almost all vaccinators knew the correct arrangement of vaccines in the ILR according to temperature sensitivity. This was in contrast to what Mallik, et al. reported, that vaccinators had poor knowledge of heat sensitive vaccines.[13]

Knowledge of the vaccinators regarding the timing of defrosting of ILR and deep freezer was poor, which needs improvement. Shake test, for testing whether a vaccine is frozen or not, should be a matter of common knowledge for the vaccinators. But, we found in the present study that just less than two-thirds of the vaccinators knew exactly about Shake test. It is imperative that vaccinators are well conversant with the temperature range to be maintained in ILR and deep freezer so that a break in cold chain can be easily detected and reported to the higher authority. In the present study, only one-fourth of the vaccinators knew the exact temperature range for deep freezer. Though, four-fifth of them knew the exact temperature range for ILR. Yuan, et al. found in their study that 57.3% individuals correctly specified the optimal temperature range for vaccine storage.[16] Ortega Molina, et al. found in their study that 61.43% knew the optimal temperature range.[17] Jeremijenko, et al. reported that educating a staff member on correct vaccine storage conditions and nominating that person to be responsible for monitoring refrigerator temperatures improves adherence to vaccine storage guidelines.[18]

On being asked about the steps incumbent to refrigerator failure, more than one-third of vaccinators told to put the vaccines in cold boxes, one-fourth told to put it in alternate storage refrigerator, one-fourth told to use the generator, 5% told to call the higher authority and 5% told to shift the vaccines in a nearby ice-cream vendor's refrigerator. Irrespective of the step that is followed in case of refrigerator failure by the vaccinators, a fixed and pre-decided plan of action should be individualized for each UHC.