Standard Operating Procedure: When and how to conduct the Shake Test

The test is used to identify freeze-damaged vaccines, which can be hazardous to individuals. The test is based on the principle that when a vaccine is frozen, the bonds between the aluminum adsorbent and the antigen are broken, causing the adsorbent to settle at the bottom of the vial when shaken. The Shake Test is applicable to freeze-sensitive vaccines, including DTP-HepB-Hib, TT, PCV13, Hepatitis B, and HPV. The test has been shown to have 100% sensitivity, specificity, and positive predictive value when carried out correctly. The test is essential for ensuring the safety and efficacy of vaccines in the supply chain. The Shake Test protocol is outlined in Annex 1 of the Standard Operating Procedure (SOP). The protocol requires that at least one member of the duty personnel in every facility that stores vaccine knows how to perform and interpret the test reliably and correctly. Vaccine that fails the Shake Test should not be distributed or administered. The SOP outlines the responsibility of logisticians, regional immunization vaccine officers, and district immunization vaccine officers in conducting the Shake Test. These personnel are responsible for looking after vaccine and checking its condition. They must be trained to conduct the Shake Test correctly and follow the protocol outlined in Annex 1. The Shake Test is typically conducted when a freeze tag or temperature-monitoring device shows a freeze alarm, or when freezing is suspected. The test is not necessary when solid frozen vaccine vials have been found. The sampling methodology for selecting the test sample depends on the number of vials suspected to have been frozen. For incoming shipments from the vaccine supplier, the SOP outlines two cases: when there is a shipping indicator in every container and when there are no shipping indicators or when they are not supplied in every container. In both cases, the suspect shipment or container is marked and isolated, and the sampling procedure described in Annex 1 is followed. For vaccine that is already in the supply chain, the SOP outlines different sampling methodologies depending on the number of vials to be tested. For small numbers of vials from the same batch, all vials are tested against the control sample. For small numbers of vials from more than one batch or type of freeze-sensitive vaccine, the Shake Test is repeated for each batch and vaccine. For large numbers of suspect vials, the sampling procedure described in Annex 2 is followed. The Shake Test results are sent to the vaccine supplier, and in the case of UNICEF-procured or donated vaccine, the results are supplied to UNICEF for a final decision on what to do with the consignment. If the decision is taken to dispose of the vaccine, all vaccine in the affected container or shipment is discarded.