POST 00579E : VACCINE FREEZING, FREEZEWATCH AND SHAKE TEST

POST 00579E : VACCINE FREEZING, FREEZEWATCH AND SHAKE TEST Follow-up on POSTS 00571E, 00574E and 00575E 4 July 2003 ______________________________________________________________ This posting contains 4 contributions and exceptionally will cover more than one specific topic as they are all related to vaccine freezing. The first translated from French is from Olivier Blanchet (mailto:[log in to unmask]) from Médecins Sans Frontières (MSF) on their method to prevent freezing. The second and third contributions are an exchange between Alasdair Wylie (mailto:[log in to unmask]) and Anil Varshney (mailto:[log in to unmask]) to clarify some points in the previous posting (00575E). Note that Anil makes an interesting suggestion that may deserve some research ! Finally, Michel Zaffran (mailto:[log in to unmask]) responds to some points brought up in Post 00575E on FreezeWatch and the Shake Test. ______________________________________________________________ To avoid freezing of vaccines and all other products that we ship under cold chain conditions from our logistical base at Merignac (France) to all our overseas missions, we have developed the following procedures: - Freezing of icepacks in freezers. - Stocking of frozen icepacks in refrigerators between 0°C and +1°C, that is frozen icepacks with some water left. - Packing of product to be shipped with cardboard in between to isolate from direct contact with icepacks. - each box contains a temperature control card as well as a single-use temperature monitor "Spytemp" (see following URL for description of this product http://www.emballiso.com/Isostar/Textes ... sostar.htm . This site is in French but I believe one may enquire at mailto:[log in to unmask] for English equivalent) In our overseas missions, we find Eutectics with fusion points in the range of -10°-0°C without it being stated on the Eutectics. In order to avoid that our teams use any type of Eutectics that would pose risks to products to be transported, we simply never send any even those with fusion points of 0°C. Even if laboratories include them in their shipments to us, we remove them before forwarding products. No incident of vaccine freezing, even suspected ones were reported since this system was put in place while it happened when we were using FreezeWatch that sometimes broke without any reason and do not indicate neither temperature reached nor duration. All this generates high costs indeed compared with the use of cards only and for the time being is not contemplated for shipments from center to periphery in our overseas missions. Olivier Blanchet Secteur technique/logistic department Médecins Sans Frontières Logistique ________________________________ Interesting question. I am not aware of any evidence that the freezing temperature and duration for the control vial for the shake test makes any difference, and I have never experienced in practice that it does. I did however see that in the same TechNet posting (00575) Anil Varshney indicated that he has experience that it does. I have asked him for clarification of the circumstances. Alasdair _________________________ Thanks for your email query about the shake test. I feel one needs to do that in practice to see the effect and come to conclusions about freezing at different temperatures and different times. What I mentioned in the email was a chance finding we noticed in Bhutan where ambient daytime temperatures in winter were approximately 8°-10°C. This was observed at a BHU (Basic Health Unit) where an immunization session was being held. The vaccines had been taken out from the refrigerator and kept in a vaccine carrier. The Hep B was frozen when the turn came to inject it. The health worker was not aware of the consequences (this is true in most field cases in most parts of many countries) He would thaw and give it. We did the shake test and it wasn't positive, meaning it could be used (but the vaccine was discarded as we insisted). We checked the refrigerator for other vaccines, none was frozen. So the conclusion was that the vaccine froze in the vaccine carrier. It was 2 - 3 hours only and the shake test was negative. How about adding some material/ chemical that would change color if frozen; this would be simpler to check -- this is just an idea. Regards, Anil ________________________________ A- UNICEF DISCONTINUES THE USE OF FREEZE WATCHES IN INTERNATIONAL VACCINE SHIPMENTS 1- Following several complaints received from the field, the use of Freeze Watch model no 9805 0°C (PIS reference E6/45) was suspended for several months in 2002 and early 2003. 2- Following an extensive review of the situation as well as a new series of tests, and taking into consideration the fact that Freeze Watch is the only freeze indicator currently listed in the PIS and available to immunization programmes, WHO/V&B has recommended, on 6 March 2003, that the purchase ban be lifted. 3- With its current design, however, the Freeze Watch gets activated at temperatures ranging from +1.5°C to -1.5°C. This means that in practice, the FW will be in some cases activated at temperatures above 0°C and that this device only provides an early warning that the vaccine may have been exposed to freezing temperatures. 4- Because of this wide temperature activation range, UNICEF Supply Division have decided to discontinue the use of this device in international vaccine shipments 5- Hence, pending the availability on the market of an affordable device which could replace the Freeze Watch, WHO/V&B is making the following recommendations : • Shipments of freeze sensitive vaccines should be thoroughly inspected of upon arrival. • The global DTP supply situation is extremely tight and great caution should be applied before deciding to reject a shipment as replacement vaccine may not be readily available. • If Freeze Watches are used : • Recipient countries should be aware that the activation of the Freeze Watch only provides a warning of possible freezing and this cannot be the only basis upon which the decision to reject a vaccine shipment is taken. • Further investigation should be done through the shake test (see below) • If Freeze Watches were not used : • Check for the presence of temperature recording devices. WHO is recommending to UNICEF SD, to vaccine manufacturers and to procuring countries that temperature recording devices (electronic or mechanical) be used. • In case freezing is suspected (either because frozen vials are found in the shipment or because of the temperature recordings ) then the shake test should be conducted (see below). 6- We are in the process of reviewing test results of electronic temperature monitoring devices tested at independent laboratories as well as validation studies conducted by either vaccine manufacturers or other partners. This review is being done with the idea of recommending these devices to replace CCM and Freeze Watch combination in each and every shipping carton. We believe inclusion of one mechanical temperature data logger (as done currently) cannot reflect the temperature exposure history of the whole shipment. Studied devices do not require downloading and temperature exposure history of the box can be read on the liquid crystal screen. B- CONDUCTING THE SHAKE TEST Shake test protocol (from Guideline for establishing or improving primary and intermediate vaccine stores. WHO/V&B/02.34) PURPOSE The SHAKE TEST is designed to determine whether adsorbed vaccines (DPT, DT, Td, TT or Hepatitis B) have been subjected to temperatures likely to have damaged them. After freezing, the vaccine no longer has an the appearance of an homogenous cloudy liquid, but tends to form flakes which settle at the bottom of the vial after shaking. Sedimentation is faster in a vial which has been frozen than in a vial, from the same manufacturer, which has not been frozen. SAMPLING The test should be conducted for all boxes where Freeze Watches are found to be activated (or temperature recordings show negative temperatures) or, if FW were not used, for samples taken from all vaccines shipping boxes. If large quantities of vials are involved (for shipments containing over 1,000,000 doses of freeze sensitive vaccines) we recommend a 10% random sampling. The vials should be selected at random from those located at the bottom of the shipping boxes. Individual batches of vaccine from a single manufacturer may behave differently. Therefore the test procedure described below should be repeated with all suspect batches. In the case of international arrivals, the shake test should be conducted on a random sample of vaccine. However, if there is more than one lot in the shipment, the random sample must include vials taken from each and every lot. • 20% or more of the samples fail the shake test, the shipment should be rejected. • the case that less than 20% of the samples fail the shake test, shipping cartons should be treated individually : Only cartons with frozen vials should be rejected PROCEDURE : Prepare a frozen control sample: Take a vial of vaccine of the same type and batch number as the vaccine you want to test, and from the same manufacturer. Freeze the vial until the contents are solid, (at least 10 hours at - 10oC) and then let it thaw. This vial is the control sample. Mark the vial clearly so that it is easily identifiable and will not be used by mistake. Choose a test sample: Take a vial (s) of vaccine from the batch (es) that you suspect has been frozen. This is the test sample. Shake the control and test samples: Hold the control sample and the test sample together in one hand and shake vigorously for 10-15 seconds. Allow to rest: Leave both vials to rest. Compare the vials: View both vials against the light to compare the sedimentation rate. If the test sample shows a much slower sedimentation rate than the control sample, the test sample has most probably NOT BEEN FROZEN and can be used. If the sedimentation rate is similar and the test sample contains flakes, the vial has probably been damaged by freezing and SHOULD NOT BE USED. Note that some vials have large labels which conceal the vial contents. This makes it difficult to see the sedimentation process. In such cases, turn the sample and reference vials upside down and observe sedimentation taking place in the neck of the vial. If the test procedure indicates that the test sample has been damaged by freezing, you should notify your supervisor immediately. Standard Operating Procedures should then be followed to ensure that all damaged vaccine is identified and that none of this damaged vaccine is distributed to the intermediate stores. Michel Visit the TECHNET21 Website at http://www.technet21.org You will find instructions to subscribe, a direct access to archives, links to reference documents and other features. ______________________________________________________________________________ To UNSUBSCRIBE, send a message to : mailto:[log in to unmask] Leave the subject area BLANK In the message body, write unsubscribe TECHNET21E ______________________________________________________________________________ The World Health Organization and UNICEF support TechNet21. The TechNet21 e-Forum is a communication/information tool for generation of ideas on how to improve immunization services. 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