Covid-19 vaccines: how they are maintained

The need for reliable storage systems at extremely low temperatures («deep freeze») has long been a priority for researchers worldwide in order to safely store valuable samples. As the first vaccines against SARS-CoV-2 are expected to receive expedited approval within the next few weeks following the very encouraging preliminary results of clinical trials, the issue of reliable deep-freeze storage solutions has come to the forefront. Vaccines against SARS-CoV-2 may require storage conditions as low as -80°C, and companies that manufacture research freezers are striving to meet growing customer demand.

The physicians of the Department of Internal Medicine at the School of Medicine of the National and Kapodistrian University of Athens—Ioannis Danasis, Panos Malandrakis, Maria Gavriatopoulou, and Thanos Dimopoulos (Rector of the National and Kapodistrian University of Athens) review the latest data.

The COVID-19 pandemic has altered the business plans of many companies, which have shifted their focus almost exclusively to the sale of freezer systems. It should be noted that the real challenge lies not so much in storing vaccines at their production sites, but in the ability to distribute them under optimal conditions at the local level. Key factors in selecting a refrigeration system include power consumption, thermal load, storage capacity, noise level, and, above all, reliability.

SARS-CoV-2 vaccines based on the technology of mRNA it is particularly vulnerable to high temperatures and they can be degraded; for this reason, efforts are being made to improve the molecule’s stability through the use of lipid nanoparticles and deep-freezing.

The BNT162b2 vaccine developed by the companies Pfizer and BioNTech requires storage and transport to the -70°C. For this purpose, special transport packaging has been designed that contains dry ice so that the temperature is maintained between -70ºC and +10ºC. By replenishing the dry ice, the vaccines can be stored for up to 15 days under these conditions. The vaccines can then be thawed and stored in the refrigerator for 5 days. Special devices for continuous temperature monitoring are used at all the steps described to detect any deviations.

The vaccine mRNA-1273 of the company Moderna It must be stored between +2°C and +8°C and protected from exposure to dust and light. According to a recent announcement by the company, the mRNA-1273 vaccine remains stable at the above temperatures for up to 30 days, at room temperature for up to 12 hours and in the freezer at -20°C for up to 6 months.

The AZD1222 vaccine University of Oxford and of AstraZeneca It can also be stored and transported at -20°C.

The Russian vaccine Sputnik V, requires storage temperatures of -20ºC.

The company's JNJ-78436735 vaccine Janssen Pharmaceuticals It can be stored and transported at refrigerator temperatures between +2°C and +8°C.

The company's NVX-CoV2373 vaccine Novavax It can be stored and transported at temperatures ranging from +2°C to +8°C.

The MRT5500 vaccine from Translate Bio in collaboration with the Sanofi, It is based on mRNA and originally required storage at -80°C; however, the molecule has now been modified to remain stable at -20°C.