POST 00485E : CHILLED WATER PACKS STUDY 10 August 2002
_______________________________________________________________
As announced in the previous posting, the preliminary results of studies of
chilled water instead of frozen icepacks for vaccine transportation to
prevent freezing are presented below by Dr. Ãœmit Kartoglu
(mailto:[log in to unmask]) from WHO.
_______________________________________________________________
INTRODUCTION
In Post 00400E (20 December 2001), I asked several questions that led WHO
to conduct a series of studies both in laboratory-controlled and field
conditions using chilled water packs during vaccine transportation. I hoped
to have the data in hand a long time ago, but the country studies’
preparation took longer than we expected. Although we are not yet in a
position to suggest a policy change in vaccine transportation using chilled
water packs, the results are so far positive and suggest that chilled water
is a safe alternative to using ice during vaccine transportation to prevent
freezing. The plan was to test chilled (2°C to 8°C) water packs performance
in vaccine transportation at country level. We have planned 6 country
studies looking at ambient and inside-the-cold-box temperatures as well as
a controlled laboratory study at 43°C and 32°C for 48 hours.
Nepal, Turkey and Zimbabwe studies are completed. The one in Southern Sudan
is in progress. We are still looking for one country to conduct the study
in EMRO region. Another country will join the group from AFRO western
coast. The laboratory study was conducted by CSIR, South Africa, under a
WHO contract. The above mentioned studies used RCW2/CF, RCW25/CF and
insulated boxes. We also used all 4 types of Vaccine Vial Monitors (VVM2,
VVM7, VVM 14 and VVM30) on dummy vaccine vials to determine whether vaccine
stability was maintained. A new series of tests will be conducted on Blow
Kings insulated vaccine carriers during August.
We hope to reach a conclusion on a possible policy change for vaccine
transportation once all these tests are completed within several months.
Full results will be published in a report and will be available to those
who are interested.
LABORATORY EVALUATION OF VACCINE CARRIER BOXES USING CHILLED WATER PACKS
This laboratory evaluation studied the thermal stability of large and small
vaccine cold boxes commonly used for vaccine transport (Electrolux RCW25/CF
and RCW2/CF). Evaluation utilized two standard 0.3 liter or twenty-four 0.6
liter icepacks in the small and large vaccine cold boxes, respectively.
Instead of being frozen, icepacks were filled with tap water and chilled to
either 2°C or 8°C (chilled water packs) and tested with vaccine carriers at
ambient temperatures of 43°C and 32°C. One set of tests was done without
any chilled water packs at an ambient temperature of 43°C to see the
difference brought by water packs (in one of the following postings after
the idea of this test was explained, it was said that it would not work
because cold water does not have any latent heat as in ice and heats up
linearly).
A set of four VVMs (VVM2, VVM7, VVM14, VVM30) were attached to the dummy
vaccine vials to which a thermocouple was also attached. Temperatures were
monitored at 5-minute intervals using a Grant Squirrel data logger with
thermocouples recording three distinct temperatures for each large vaccine
carrier and two distinct temperatures for each small vaccine carrier. In
summary, the five tests performed for large and small vaccine carriers were:
1. Load and water packs at 2°C, ambient temperature 43°C
2. Load and water packs at 8°C, ambient temperature 43°C
3. Load at 2°C, no water packs, ambient temperature 43°C
4. Load and water packs at 2°C, ambient temperature 32°C
5. Load and water packs at 8°C, ambient temperature 32°C
As for large vaccine carriers, at ambient temperature of 43°C, it took 49
hours to reach 20°C with 2°C chilled water packs and vaccine load, while
this period was 37 hours when 8°C chilled water packs were used. The
shortest time (5 hours) was measured with no chilled water packs and 2°C
vaccine load test. Similar figures for 32°C ambient temperature were
recorded as 60 hours and 50 hours (no test was conducted at 32°C with no
water pack). VVM readings were recorded both before and after the test. In
all tests except for VVM2 with no water packs at 43°C ambient, all 4 types
VVMs were found to be acceptable (use the vaccine) before and after.
As for small vaccine carriers, at ambient temperature of 43°C, it took 7.5
hours to reach 20°C with 2° C chilled water packs and vaccine load, while
this period was 5 hours when 8°C chilled water packs were used. It took
only 1 hour to reach 20°C with no chilled water packs and 2°C vaccine load
test. Similar figures for 32°C ambient temperature were recorded as 9 hours
and 6 hours (no test was conducted at 32°C with no-cold water pack). VVM
readings were recorded both before and after the test. In all tests except
for VVM2 with 2°C chilled water packs at 43°C ambient, 8°C chilled water
packs at 43°C ambient and no water packs at 43°C ambient, all 4 types VVMs
were found to be acceptable indicating that the vaccine can be used safely
after the test.
FIELD EVALUATION IN NEPAL (RESPONSIBLE PERSON : VENKAT AIYER, WHO)
In Nepal, five transportation tests were conducted using large RCW25
vaccine carriers, each with twenty ice packs chilled to between 5°C and
5.9°C. Transportation distances had a range of 221 to 584 kms (6 to 27
hours). In all transportation tests, all four VVMs (VVM2, VVM7, VVM14,
VVM30) indicated vaccine potency was not compromised. The ambient
temperatures had a range from 10°C to 50°C. Yet the vaccine carrier
temperatures remained between 5°C and 13°C. This indicated that the
insulation of the RCW 25 vaccine carrier was capable of maintaining safe
vaccine temperatures with chilled water packs despite high ambient
temperatures. Additional tests will be conducted in Nepal to increase the
number of vaccine transportation studies.
FIELD EVALUATION IN ZIMBABWE (RESPONSIBLE PERSON : SERGE GANIVET, WHO)
In Zimbabwe, 11 transportation tests were conducted using insulated boxes
for vaccine transportation. Twelve, 0.4 liter ice packs were chilled to
between 4°C to 5°C for each transportation test. Transportation distances
had a range of 80 to 583 kms (1 hour to 4 days). In all of the
transportation tests, all four sets of VVMs (VVM2, VVM7, VVM14, VVM30)
indicated that vaccine potency had not been compromised.
FIELD EVALUATION IN TURKEY (RESPONSIBLE PERSON : BIRHAN ALTAY, MOH)
In Turkey, 10 transportation tests were conducted using insulated boxes for
vaccine transportation. Transportation distances had a range of 10 to141
kms (all in one day). Despite using fewer chilled water packs than standard
(at 3°C to 6°C), all four sets of VVMs (VVM2, VVM7, VVM14, VVM30) indicated
that vaccine potency had not been compromised.
__________________________________________________________________
For those who are interested in the study protocol, please contact Dr. Ãœmit
Kartoglu directly at
(mailto:[log in to unmask])
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