TechNet-21 - Forum

This forum provides a place for members to ask questions, share experiences, coordinate activities, and discuss recent developments in immunization.
  1. Yann Letallec
  2. Vaccines and delivery technologies
  3. Monday, 20 August 2012
Dear colleagues, Here is a rather technical question: what to do with a "non freeze-sensitive" vaccine after exposure to freezing? The ultimate objective of my question is to refine and validate operational guidance for field workers. In the case of the "freeze-sensitive" vaccines (commonly HepB, penta, PCV, TT), the operational guidance is rather clear -- that vaccines exposed to freezing temperature should be tested (with a shake test) and discarded if they don't pass the test (vials frozen solid can be discarded immediately). The shake test only works with vaccines with an aluminum adjuvant (perhaps others compounds too), a component that classifies the vaccines as "freeze-sensitive" to start with if I am not mistaken. Then, there are vaccines for which the shake test "does not work"; usually these vaccines are not classified as freeze-sensitive -- nonetheless their manufacturer label might ask for a storage between 2-8°C. Thus the question: If a field worker finds a vial from such vaccine that is frozen solid (an unfortunate but not impossible situation), should the vaccine be discarded? Thanks you in advance for your comments, Yann
Alejo Bejemino Accepted Answer
Vaccine storage temperatures at different immunization storage levels and for different storage periods are summarized as follows: OPV storage temperatures are -15 C to -25 C at the primary level for a maximum storage period of 6-12 months. However its storage temperatures at the health facility/service delivery levels are +2 C to +8 C for a maximum period of 1 month. Freeze-dried/lyophilized vaccines (BCG, Measles, JE, Hib lyo, Meningitis, MR, MMR, YF, etc.) storage temperatures are +2 C to +8 C at the primary level for a maximum storage period of 6-12 months and at the health facility/service delivery level for a storage period of 1 month. If diluent is included in the vaccine packaging it should also be stored in the +2 C to +8 C cooler. If diluent is supplied separately, it can be stored outside the cold chain but must be cooled before use. If there is a temporary shortage of storage space in the +2 C to +8 C cooler, these vaccines can stored in the -15 C to -25 C freezer. However, diluents should never be frozen. Freeze-sensitive or other vaccines that do not belong to the above (TT, DPT, Penta, etc.) storage temperatures are +2 C to +8 C at all levels for a storage period of 6-12 months for the primary level and 1 month for the health facility/service delivery level. As Michel had mentioned freezing is not damaging to any freeze dried/lyophilized vaccine including OPV. OPV can be safely frozen and unfrozen repeatedly. Freeze-dried/lyophilized vaccines can now be stored at +2 C to +8 C. But if -15 C to -25 C storage space is available these vaccines can be safely stored. The risk of freeze-sensitive vaccines being frozen is high at the lower level, where all vaccines are stored in one refrigeration compartment. Freezing of these vaccines is also possible with the use of unconditioned frozen ice packs inside the passive containers during transport or outreach vaccination activities. It is therefore important that each health worker should be trained how to handle vaccines particularly the freeze-sensitive vaccines. The use of reliable and WHO PQS pre-qualified cold chain equipment should also be observed and practised by health officers in the procurement and replacement of cold chain equipment. It is true that due to diminishing polio campaigns the storage space allocated for OPV is significant and can be used for storage of freeze-dried/lyophilized vaccines, particularly at the national and sub-national levels. Another important factor in the calculation of storage capacity is the vaccine wastage multiplier. A high wastage multiplier will result in a request for more vaccines. These vaccines that were added due to a high wastage multiplier have to be stored in the cold chain. Therefore a higher vaccine wastage multiplier is translated into higher costs due to additional storage space requirement as well as due to increase in quantity of vaccines. Vaccine wastage must be recorded, monitored and reduced at each level of the cold chain system. Alejo H. Bejemino Independent Consultant Cold Chain and Vaccine Management
Mojtaba Haghgou Accepted Answer
I am glad that Michel brought this issue up. The fact that freeze-dried vaccines and OPV can easily be stored at sub-zero temperatures at all levels is a significant programmatic issue. Now that the number of polio campaigns is diminishing, a number of freezer-rooms at central vaccine stores and many freezers at lower levels of the supply chain will be ready for storing BCG, MCV, YF, etc. and new vaccine such as rota virus vaccines. Therefore, in estimating the storage capacity, we should keep the possibility of storing above vaccines in freezer-rooms and freezers in mind. This may reduce purchasing additional cold rooms and refrigerators for new vaccines. This will not only be a cost saving measure, it will also reduce the space required for installation of new cold rooms.
Moderator Accepted Answer
Admin
Many thanks to Michel Zaffran, EPI Coordinator, WHO, for this response. Freezing is not damaging to any lyophilized /freeze dried vaccines such as BCG, Measles, MR, MMR, yellow fever , Men A, JE, etc… this applies to OPV and Rotavirus as well. The thermostability profile of vaccines can be found at: http://www.who.int/vaccines-documents/DocsPDF06/847.pdf. PATH has also recently published vaccine stability data which can be located at: Vaccine Resource Library For OPV, studies conducted by WHO and the UK NIBSC laboratories in the mid-1990s have demonstrated that up to 10 freeze/thaw cycles do not affect the potency of the vaccines. So freezing of these vaccines should not prevent use of the vaccine. A Freeze VVM, if it ever becomes available at an affordable price, would not work any differently than a fridge-tag or a freeze-tag. It would activate at a pre-set temperature and it would not necessarily indicate true damage by freezing but rather exposure to the above pre-defined sub-zero temperature. The best guidance therefore that can be provided as of today is: 1) to avoid freezing and exposure to sub-zero temperatures through appropriate monitoring of the cold chain and proper vaccine management practices; 2) in case of exposure to sub-zero temperatures and in case freezing is suspected and the shake test cannot be applied, then the vaccine should not be used and the matter referred to higher levels. If significant quantities of vaccines are at stake, then a specific investigation could be carried out.
prabirkc Accepted Answer
For NON freeze sensitive vaccines- BCG and Measles are powders (freeze dried) so the question does not arise. OPV is kept at minus 20 degrees and later kept at 2 to 8 degrees in the district. Here we have no instructions for the health worker if it (OPV) accidentally freezes again in the cold chain. One incident happened where the pH indicator turned yellow (OPV is usually light pink- phenolphthalein probably). This was said to be due to repeated freezing and thawing. After checking- health workers were told to USE the vaccine. This was possibly for logistic reasons. If freeze indicators are used and different vaccines are frozen in the same equipment (ILR or Deep Freeze) the logistic solution may be to seal the contents and dispose it as a single set. Pick and choose might lead to frozen DPT or Hep B getting out with the OPV.


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