There may be no need to keep the Pfizer and BioNTech coronavirus vaccine and other similar vaccines at -70掳C, potentially making it much easier to distribute them across the world. Two other teams using the same messenger RNA (mRNA) technology for their vaccines have found that they remain stable for at least three months in a normal fridge.
The Pfizer and BioNTech vaccine candidate generated great excitement around the world this week when the companies announced that it appears to be more than 90 per cent effective based on early results. Yet concerns were raised about the fact that the vaccine needs to be stored at between -70掳C and -80掳C. This is far colder than standard freezers can manage and would greatly complicate the vaccine鈥檚 storage and distribution.
But two other vaccine candidates using the same mRNA technology as the Pfizer and BioNTech vaccine can be stored at higher temperatures than this. Anna Blakney at Imperial College London has told New 女生小视频 that the vaccine candidate being developed by her team is stable for months at 4掳C, the same temperature as a standard fridge.
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Another vaccine candidate developed by CureVac in T眉bingen, Germany, remains stable for at least three months when stored at a standard refrigerator temperature, .
The same should be true for the Pfizer and BioNTech vaccine, says Blakney. 鈥淚 guarantee that they are doing the exact same studies.鈥�
The mRNA vaccines consist of strands of RNA that code for the coronavirus spike protein, a key part of the virus that allows it to infect humans. When the RNAs from the vaccine enter human cells, the cells start making the spike protein, prompting an immune response without an infection.
Naked RNAs 鈥� those without anything protecting them 鈥� would be rapidly chewed up by enzymes in the blood. In the vaccines, they are packaged in tiny droplets of fat, called lipid nanoparticles or LNPs, which protect them and help them get into cells.
All three groups are using LNPs made by a company based in Vancouver, Canada, called . The firm鈥檚 CEO, Thomas Madden, says the decision to store these vaccines at between -70掳C and -80掳C was made out of 鈥渁n abundance of caution鈥�.
鈥淭here鈥檚 no technical limit鈥� currently on the temperature at which the vaccine should be stored, he says. The vaccines were just developed so fast that there was no time to do the necessary tests to establish how stable they are at higher temperatures, says Madden.
Once vaccine makers such as Pfizer and BioNTech have sufficient evidence of stability at higher temperatures, they can apply to regulators to change the conditions of approval. This evidence might need to include animal tests, but shouldn鈥檛 require more human ones, says Madden.
The findings of the Imperial and CureVac teams should apply to the Pfizer and BioNtech vaccine too, but regulators require stability to be established separately for each individual vaccine, he says.
New 女生小视频 contacted Pfizer and BioNTech for comment but hadn鈥檛 received a response by the time of publication.
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