Thursday, 17 October 2002
  0 Replies
  2.2K Visits
POST 00511E : USE OF VVMs Anil Varshney (mailto:[log in to unmask]) from India has observations and questions on VVM use, to which Ümit Kartoglu (mailto:[log in to unmask]) from WHO provides answers. _____________________________________________________ I wish to present some observations which need to be cleared In East Timor, CCM, VVM and Freeze Watch are in use in the cold chain, which is LPG-run SIBIR refrigerator with front door opening. The following points were noticed : 1. VVM on OPV and BCG showed different stages even when kept for the same duration at the facility while the VVM in OPV was in stage 2-3 the CCM marker showed that the vaccine could be used for 2 months. 2. Freeze Watch was a good indicator, but its interpretation from central to peripheral level was poor – showing there is need to increase the awareness through training and other methods. Questions raised 1.Why different VVM stages in BCG and OPV , do both VVM have different characteristics? 2. In most cases the VVM on OPV appeared to show that the cold chain is inadequate while CCM cards allowed for more relaxation. If VVM is more sensitive than its better NOT to use the CCM card as the health worker is likely to get confused.. 3. If the cold chain is not adequate for OPV, it does not necessarily mean that it is not OK for other vaccines. 4. Since OPV is coming with VVMs, the CCM card should mention other vaccines only (without OPV) in order to avoid confusion in the peripheral health facilities. __________________________________________________________ Anil's contribution and questions he raised show the importance of having a good reference material on Vaccine Vial Monitors (VVM). I would like to announce that the following document will be made available soon (within a month or so) both in electronic and hard copy: "Getting started with vaccine vial monitors: Questions and answers on field operations". This document will replace the old "Vaccine Vial Monitor and open vial policy - questions and answers WHO/EPI/LHIS/96.01" Post 00444E (3 April 2002) was sent with an attachment: "Specifications for Vaccine Vial Monitors (E6/IN5, 25 March 2002)". It is thus highly recommended that readers revisit this posting and the attachment through TechNet21 archives at: http://listes.ulaval.ca/cgibin/wa?A2=ind0204&L=technet21e&F=&S=&P=274 Coming back to Anil's questions: 1. Why different VVM stages in BCG and OPV , do both VVM have different characteristics? Yes. VVMs are manufactured with four specific time-temperature sensitivities. They are the following: VVM type 37oC 25oC 5oC VVM30 30days 193days >4years VVM14 14days 90days >3years VVM7 7days 45days >2years VVM2 2days NA 225 days Each type of VVM is designed to mimic the heat stability of the vaccine to which it is attached. Types of VVMs are assigned by WHO based on the heat stability data of that particular vaccine provided by the vaccine manufacturer. VVM for OPV and BCG are of different types and should behave differently. BCG is a more heat-stable vaccine compared to OPV, and if both vaccines with VVMs attached are kept at the same temperature, OPV VVM will reach its discard point much before BCG VVM. Unfortunately it is NOT possible to provide a list that shows VVM type by vaccines. For each presentation, WHO reviews the heat stability data and assigns an appropriate category for that particular one. For example, BCG from one manufacturer can take VVM14 while another one may receive VVM30. However, we know that all OPV is VVM2. 2. In most cases the VVM on OPV appeared to show that the cold chain is inadequate while CCM cards allowed for more relaxation if VVM is more sensitive than its better NOT to use the CCM card as the health worker is likely to get confused. We have to make a clear distinction between the purpose of the Vaccine Cold Chain Monitor (CCM) and VVM. CCM cards, packaged with each consignment of vaccine from UNICEF, indicate when the temperature limits of the cold chain have been passed. The VVM takes the monitoring procedure one step further and shows the impact of any such temperature changes on each individual vial of vaccine. The CCM monitors the journey while the VVM shows how "each passenger" has fared. The CCM is a useful managerial tool for checking the arrival of vaccine shipments at primary and intermediate stores and may also be used in conducting national cold chain surveys. The VVM provides guidance on the use of each vial of vaccine. In the presence of both VVM and CCM, VVM reading should have the priority. One should keep in mind that VVM is the only time-temperature indicator that accompanies the individual vial starting from the primary packaging of the vaccine at the manufacturer's facility until the time it is used in the field. This is not possible with CCM. It is also highly possible that a CCM activated at any point of the cold chain will not have the historical information of heat exposure of the vaccines present in the cold chain at that point in time. Therefore, it is very difficult to make a correct interpretation of a CCM reading for making managerial decisions at different levels of the cold chain system. 3. If Cold chain is not adequate for OPV it does not necessarily mean that it is not OK for other vaccines? Different vaccines require different temperature ranges for transportation and storage. WHO recommends that OPV be kept at -15° to -25°C at primary and regional intermediate vaccine cold stores. Rest of the vaccines can be safely kept at +2° to +8°C at all levels. WHO no longer recommends that freeze-dried vaccines be stored at -20°C. Storing them at -20°C is not harmful but it is unnecessary. Instead, these vaccines should be kept in refrigerators and transported at +2° to +8°C. 4. Since OPV is coming with VVM, the CCM card should mention other vaccines only ( without OPV) in order to avoid confusion in the peripheral health facilities. As mentioned under 2nd answer, CCM is mainly designed for checking the arrival of vaccine shipments. WHO requires that one CCM card is inserted into each vaccine shipping box. For example, a shipment of 1,000,000 doses of 10 dose/vial DTP vaccine will come around 50 shipping boxes with a CCM card in each. If the same box is transferred to a lower level (intermediate vaccine store), it can definitely go with the original CCM card. However, it is very unlikely that any country can have enough CCMs to accompany distribution of vaccines down to service level. Activating new CCM card is NOT a solution and is NOT recommended since it will give misleading information. ----------------------------------------------------------------------------- All members of the TechNet21 e-Forum are invited to send comments on any posting or to use the forum to raise a new discussion or request technical information in relation to immunization services. As soon as administratively possible, TechNet21 e-Forum will operate 3 language-specific lists in English, French and Spanish. The comments made in this forum are the sole responsibility of the writers and do not in any way mean that they are endorsed by any of the organizations and agencies to which the authors may belong. ----------------------------------------------------------------------------- CONTRIBUTIONS: Contributions to: or use your reply button! The TechNet21 e-Forum welcomes new subscribers who are involved in immunization services.SUBCRIBE: To subscribe, send an e-mail to: Leave the SUBJECT area BLANK, do not type anything. In the body text, just write: Subscribe TECHNET21E Surname Name Do not use any accents in your name and surname. UNSUBSCRIBE: To unsubscribe, send an e-mail to: Leave the SUBJECT area BLANK, do not type anything. In the body text, just write: Unsubscribe TECHNET21E ------------------------------------------------------------------------------ ARCHIVES Archives of posted messages classified by month starting with 1 January 2000 are accessible to all TechNet21 subscribers at the following site : http://listes.ulaval.ca/listserv/archives/technet21e.html Archives for postings prior to January 2000 can be found at the following site : http://www.who.int/vaccines-access/Vaccines/Vaccine_Cold_Chain/Technet Or by request to the Moderator at mailto:[log in to unmask] ------------------------------------------------------------------------------ Archives for files (documents) are under revision to clean old documents and drafts that are already replaced with new ones, and will be made available soon at a specific site. ------------------------------------------------------------------------------ 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. It is moderated by Claude Letarte and is hosted in cooperation with the Centre de coopération internationale en santé et développement, Québec, Canada (http://www.ccisd.org) -----------------------------------------------------------------------------
There are no replies made for this post yet.