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Effect of thermal ballast loading on temperature stability of domestic refrigerators used for vaccine storage.

ABSTRACT: Vaccine temperature control failures represent a significant public and private healthcare cost. Vaccines damaged by excessive heat or freezing lose their effectiveness, putting public health at risk. Some vaccine administration programs recommend placing water bottles inside domestic refrigerators used for vaccine storage as a thermal ballast, to mitigate temperature excursion risks. However, the effect of variable thermal ballast loading on refrigerator performance has not been thoroughly quantified or documented, and generalized programmatic recommendations are subject to end-user interpretation. Here we show that a thermal ballast load comprising ten to fifteen percent of the total refrigerator storage volume provides a measurable effect on domestic refrigerator temperature stability during power outage events, maintaining vaccine temperatures between 2 °C and 8 °C for 4 to 6 hours without power. Thermal ballast usage does not reliably reduce the frequency or severity of temperature excursions caused by repeated door opening, accidental "door left open" events, or refrigerator defrost cycle activation. Use of a moderate thermal ballast load is a practical strategy for mitigating temperature excursions risks in areas with frequent or protracted power outages, but the practice has limited benefit in other adverse scenarios. Empowering providers to make informed decisions about the use of thermal ballast materials supports better, safer vaccine management.

SUBMITTER: Chojnacky M

PROVIDER: S-EPMC7343171 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Effect of thermal ballast loading on temperature stability of domestic refrigerators used for vaccine storage.

Chojnacky Michal M Rodriguez Alexandra L AL

PloS one 20200708 7

Vaccine temperature control failures represent a significant public and private healthcare cost. Vaccines damaged by excessive heat or freezing lose their effectiveness, putting public health at risk. Some vaccine administration programs recommend placing water bottles inside domestic refrigerators used for vaccine storage as a thermal ballast, to mitigate temperature excursion risks. However, the effect of variable thermal ballast loading on refrigerator performance has not been thoroughly quan ...[more]

PMID: 32639973

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Project description:Cold chain maintaining is least stable at its end, where domestic storage often represents one of the most critical links because of storage time and inappropriate temperatures, increasing the risk of food-borne outbreaks in domestic households. Considering the time-temperature profile of refrigerators as a food safety indicator, the purpose of this study is to gain insight into refrigeration temperatures in parallel with refrigerator and household characteristics that could potentially influence the refrigeration temperatures. During a 24 h period in 15-min intervals, internal temperature of the test product, refrigerator air and ambient air temperatures were measured with one penetration and two air probes coupled with a data logger. The internal temperature of the test product was measured with pre-prepared "Karlsruhe Test Material", which had thermal properties similar to those of lean beef. Refrigerator and household characteristics were collected with a predefined observational sheet and short, structured questionnaire. In total, 50 households and their refrigerators were included. Gaps related to the cold storage and cross-contamination were observed. Temperature displays were present in 16% while control thermometers were not observed at all; 20% of the refrigerators enabled 24 h average internal temperature lower than 4 °C, 30% between 4 and 6 °C and 50% over 6 °C. Refrigerator age, type and load were observed but had no significant impact, which suggests thermostat setting as a key factor influencing refrigerator temperatures. Food distribution inside refrigerators was related to the refrigerator load with significant risk for cross-contamination in overpacked refrigerators. High temperatures combined with a non-systematic distribution of food in the refrigerator, expired dates of durability, and non-systematic cleaning strategies allow favourable preconditions for food infections occurring at the end of the food supply chain. Tailored acceleration of existing food safety messages could and should help consumers to minimise food safety risks, improve food quality, and reduce food wastage.

Project description:The majority of current vaccines depend on a continuous "cold chain" of storage and handling between 2 and 8°C. Vaccines experiencing temperature excursions outside this range can suffer from reduced potency. This thermal sensitivity results in significant losses of vaccine material each year and risks the administration of vaccines with diminished protective ability, issues that are heightened in the developing world. Here, using peptide self-assemblies based on the fibril-forming peptide Q11 and containing the epitopes OVA323-339 from ovalbumin or ESAT651-70 from Mycobacterium tuberculosis, the chemical, conformational, and immunological stability of supramolecular peptide materials were investigated. It was expected that these materials would exhibit advantageous thermal stability owing to their adjuvant-free and fully synthetic construction. Neither chemical nor conformational changes were observed for either peptide when stored at 45°C for 7days. ESAT651-70-Q11 was strongly immunogenic whether it was stored as a dry powder or as aqueous nanofibers, showing undiminished immunogenicity even when stored as long as six months at 45°C. This result was in contrast to ESAT651-70 conjugated to a protein carrier and adjuvanted with alum, which demonstrated marked thermal sensitivity in these conditions. Antibody titers and affinities were undiminished in mice for OVA323-339-Q11 if it was stored as assembled nanofibers, yet some diminishment was observed for material stored as a dry powder. The OVA study was done in a different mouse strain and with a different prime/boost regimen, and so it should not be compared directly with the study for the ESAT epitope. This work indicates that peptide self-assemblies can possess attractive thermal stability properties in the context of vaccine development.Almost all current vaccines must be maintained within a tight and refrigerated temperature range, usually between 2 and 8°C. This presents significant challenges for their distribution, especially in the developing world. Here we report on the surprisingly robust thermal stability of a self-assembled peptide vaccine. In particular a self-assembled peptide vaccine containing a tuberculosis epitope maintained all of its potency in mice when exposed to an extreme thermal treatment of six months at 45°C. In a different mouse model, we investigated another model epitope and found some storage conditions where potency was diminished. Overall this study illustrates that some self-assembled peptide vaccines can have remarkable thermal stability.

Project description:BACKGROUND:This study examined the effect of storage temperature on the protein profile of human plasma. Plasma samples were stored for 13?days at -80°C, -20°C, +4°C and room temperature (20-25°C) prior to proteomic analysis. The proteomic comparisons were based on the differences of mean intensity values of protein spots between fresh plasma samples (named "time zero") and plasma samples stored at different temperatures. To better understand the thermally induced biochemical changes that may affect plasma proteins during storage we identified proteins with different expressions with respect to the time zero sample. RESULTS:Using two-dimensional electrophoresis followed by MALDI-TOF MS and /or LC-MS/MS 20 protein spots representing 10 proteins were identified with significant differences in abundance when stored at different temperatures. Our results, in agreement with various authors, indicate that during storage for a short period (13?days) at four different temperatures plasma proteins were more affected by degradation processes at +4°C compared to the other temperatures analysed. However, we founded that numerous protein spots (vitamin D binding protein, alpha-1-antitrypsin, serotransferrin, apoplipoprotein A-I, apolipoprotein E, haptoglobin and complement factor B) decrease in abundance with increasing temperature up to 4°C, but at room temperature their intensity mean values are similar to those of time zero and -80°C. We hypothesize that these proteins are labile at 4°C, but at the same time they are stable at room temperature (20-25°C). Furthermore we have grouped the proteins based on their different sensitivity to the storage temperature. Spots of serum albumin, fibrinogen gamma chain and haptoglobin are more resistant to the higher temperatures tested, as they have undergone changes in abundance only at room temperature; conversely, other spots of serum albumin, fibrinogen beta chain and serotransferrin are more labile as they have undergone changes in abundance at all temperatures except at -80°C. CONCLUSIONS:Although there are many studies concerning protein stability of clinical samples during storage these findings may help to provide a better understanding of the changes of proteins induced by storage temperature.

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Effect of thermal ballast loading on temperature stability of domestic refrigerators used for vaccine storage.

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Effect of thermal ballast loading on temperature stability of domestic refrigerators used for vaccine storage.

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