The European Medicines Agency (EMA) on Monday recommended a change to the approved storage conditions of the Pfizer-BioNTech COVID-19 vaccine which changes the way these vaccines are handled in vaccination centres across the European Union (EU).
In February, the US Food and Drug Administration (FDA) had allowed undiluted vials of the vaccine to be stored at conventional temperatures for a period of up to two weeks. Recently, the US and Singapore approved the Pfizer-BioNTech vaccine for use in children between the ages of 12-15 years.
What is the change in the storage of these vaccines?
With the new recommendations, an unopened thawed vial of the Pfizer-BioNTech vaccine can be stored between 2-8 degrees Celsius for up to a month, which means that it can be stored in a regular refrigerator once it has been taken out of the deep freeze. Before this, an unopened thawed vaccine vial could be kept in a regular refrigerator for a period of only up to five days.
This increased flexibility in storing and handling of the vaccines is expected to positively impact the vaccine rollout in the EU, which has faced some problems since the vaccination drive started. The EMA has said that the change was approved after additional stability data submitted to the agency was assessed.
Why do mRNA vaccines need to be stored at such low temperatures?
According to an article in Science News, mRNA vaccines need to be stored at much lower temperatures than some other kind of COVID-19 vaccines because RNA is much less stable than DNA, which is due to the sugars that their molecules are made up of. The second reason for the relative instability of RNA is because of its shape, which is a single strand, while DNA is expressed as a double-stranded helix.
How is the Pfizer/BioNTech vaccine administered?
The mRNA vaccine called BNT162b2 was initially meant for individuals who are 16 years or older and is administered in two doses of 30 μg each, given at least 21 days apart. The vaccine is injected into the person’s upper arm and takes a few weeks after the completion of the second dose to work.
How does the vaccine work?
One of the essential ingredients of this vaccine is the messenger RNA or mRNA, which carries instructions to create the SARS-CoV-2 virus’s so-called spike protein, which makes it easy for the virus to bind to cells in the body. Once the mRNA vaccine is injected into the body, it instructs the body’s cells to create copies of this spike protein. The idea is to trigger the body’s immune system response similar to if the individual had actually been infected by the virus.
Therefore, once the vaccine is able to trigger this response, the immune system should be able to produce the antibodies necessary to fight the infection, thereby potentially protecting the individual.