POST 00575E : VACCINE FREEZING
Follow-up on POSTS 00571E and 00574E
28 June 2003
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This posting contains three contributions. The first is from Pham Ngoc Len
(mailto:[log in to unmask]) from UNICEF. He brings up an issue related to
vaccine freezing, the shake test.
The second contribution is from Alasdair Wylie
(mailto:[log in to unmask]) bringing up many still unanswered
questions. Finally Anil Varshney (mailto:[log in to unmask]) from India
further contributes to the discussion. Besides many practical suggestions,
please note that he also raises questions about the shake test. This could
deserve a separate discussion.
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1-- Yes, it is good to dialogue on this issue. I have the experience that
whatever we try to improve, if the suppliers of the vaccine did not take
this seriously then it become less useful. When vaccine was frozen then the
shake test was used to identify the damaged vials of the shipment. The
question is the validity of the shake test, and how to get a correct sample
for this exercise remains a question.
Pham Ngoc Len
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2-- A few comments, and some more questions and suggestions on this issue,
though not restricted to the "cold climates" scenario:
1. Yes it is not just refrigerator performance and control. Vaccine
freezing in transport between district/health centre/outreach sessions has
been found in the past (eg Pakistan EPI review 1998) and one suspects is
still a continuing and frequently unobserved/unreported/undocumented
problem in many places.
In 2001 a vaccine freezing investigation was to be initiated in Nepal by
SEARO following reports of DPT freezing during an EPI assessment there
which I led in 2000. It would be interesting to know what the study
findings were and what if any changes in vaccine management were made as a
result. I note that this study was not mentioned in the "Technology and
Operations Panel" (TOP) February meeting report on Overcoming Freezing in
the Cold Chain (Post 00566)
2. Vaccine freezing risks, risk assessment and prevention should be a
standard element in all logistician's basic and refresher training and
should also be on the agenda at all regional managers meetings.. Was it
included in the recent AFRO logisticians workshops? And is it included in
any planned such regional/subregional workshops or training elsewhere?
(none shown on training courses section of TechNet website.) Is it on the
agenda at the next EMRO Regional Managers meeting starting 29 June?
While policy and new hardware development for the future is underway, best
efforts must be made now to help managers and staff understand risks and
minimise them, using what tools and procedures they have available now,
specific to country circumstances. The FreezeWatch indicator and the Shake
Test have both been available for about 20 years and have been
substantially neglected for reasons that are essentially management rather
than technical. (Does this sound familiar?). New or updated one page "Job
Aids" (PATH has good examples) should be prepared and widely disseminated,
but are not of course sufficient in themselves as Mr. Baru quite rightly
points out.
3. Is the "Technology and Operations Panel" (see above) - nothing about
which was mentioned on TechNet Forum until the report of the February
meeting came out - in effect to act as the working group on prevention of
vaccine freezing which is one of a number of TechNet working groups which
were to have been formed after the 2001 New Delhi TechNet meeting, or if
not what is happening?. There are other questions/issues raised but
apparently still awaiting answers for example on Hep B freezing temperature
and its implications, last asked Post 00506 last October.
4. FreezeWatch reliability: Purchasing was suspended on WHO advice in May
2002 (Post 00470) following field reports of apparently
incorrect/unreliable activation. This issue was asked about at the February
TOP meeting referred to above and the meeting report received in May
includes a footnote advising that WHO lifted the purchase ban on 6 March
2003. Nothing has been reported on TechNet about this or about the findings
of the investigation which was undertaken because of the field reports.
Even if other mechanisms are being used to communicate information on
purchasing matters to regional and country offices it would presumably be
useful to let TechNet members know?
Best regards
Alasdair Wylie
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3-- I wish to compliment PATH and WHO for compiling the data on freezing of
vaccines. This has provided the insight that vaccine freezing is an issue
which needs to be addressed. I feel instead of quantification, one must try
and undertake remedial actions at different levels, from service delivery
to national.
The subject of freezing is as old as the immunization programme and
freezing takes place not by design but by lack of knowledge/information,
training, understanding of the cold chain, supervision and monitoring. It
happens in all stages and at all levels from country level to the service
delivery levels.
What is needed is the percolation of the knowledge and information on how
to stop freezing turned into SIMPLE ACTION POINTS with clarity for each
level in their respective fields.
Some observations based on visits as well as studies on cold chain
logistics show that freezing is quite common in cold areas in mountains and
becomes unavoidable due to lack of electricity and ambient temperatures
being very low . Even disconnecting the fridge will not help as ultimately
it will reach ambient temperatures.
The following have also been noted concerning freezing. The Hepatitis B
froze within 2 hours of taking out from cold chain store into the vaccine
carrier due to direct contact of the vial, shake test was negative, the
health personnel was not aware of the consequences of the freezing and the
vial was thawed and used.
Similarly vaccines kept in cold boxes during cleaning and defrosting of the
refrigerator, Hep B, DPT , TT froze due to direct contact. However Hep B
vials in individual packing did not freeze.
This was also verified by demonstrating the same during a training session
on Immunization. Thus proving the usefulness of cartons preferably made of
thermocool or plastic or even cardboard to protect from freezing. Even
after 48 hours of direct contact with icepacks, Thermocool was the best. In
warmer climate freezing happens when there is disruption in electric
supply. On restarting of electricity, cooling is more leading to freezing
of vaccine vials lying at the lower level
Another observation was that when the vaccines were frozen for 2 to 6 hours
the shake test was negative, no flocculation sediment occurred, however
those frozen for 10 hours or more (overnight) showed positive shake test –
any explanation ? What effect on potency and sero conversion, Serum
Institutes studies also do not provide answer to this observation.
Some Options as Action Points suggested :
1. The vaccine vials should preferably come in plastic packing
individually or cardboard (plastic is better). This will lead only to 2- 5%
increase in total volume for storage. And at most peripheral service
delivery points, NO additional space will be required
2. Use Freeze Watch universally at all levels (with instructions in BOLD
that "DO NOT USE" if the freeze watch shows leakage of fluid) as the
vaccines are now destroyed and not valid.
3. While storing at district / PHC level use Thermocool boxes to keep the
freeze sensitive vaccines. (This will delay freezing).
4. The ILR should carry markings on the side where to keep which vaccines
5. Important instructions like “FREEZING DESTROYS VACCINESâ€
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