Antivenoms, hepatitis B vaccine and oral polio vaccine can be considered for storage and handling outside the cold chain following the innovative ‘controlled temperature chain’ approach

Abstract

Possible applicability of controlled temperature chain (CTC) for selected antisera and vaccines was evaluated. Bivalent oral polio vaccine (OPV), hepatitis B vaccine (HepB vaccine; monovalent and combined) and antisera (lyophilized and liquid scorpion-antivenom and liquid snake-antivenom) were tested. Samples were stored at accelerated (35 ± 5 °C) and freezing (−25 ± 5 °C) conditions for 24 h, one week and one month in addition to recommended storage condition (2–8 °C), except OPV samples that were tested at accelerated and refrigerated (2–8 °C) conditions compared to recommended storage conditions (−25 ± 5 °C). All samples were tested for potency. Protein content and composition were determined for antisera samples. All vaccine vial-monitors were evaluated. HepB vaccine was subjected to aluminum-content assay, shake test and microscopical examination. No significant change in antisera potency was detectable under accelerated condition for a week. OPV stored in refrigerator for a month and at accelerated condition for 48 h maintained acceptable potency. Monovalent and combined HepB vaccine maintained acceptable potency under accelerated condition for a month and a week, respectively. Freezing adversely affected HepB vaccine. In conclusion, reevaluation of storage conditions of tested products is urgently required; this can reduce storage costs and improves their availability. Other products should be tested for possible CTC applicability.