You may have felt this muscle pain in your arm after your Covid-19 vaccine.
An unpleasant feeling that probably subsided after 48 hours.
It may have prevented you from raising your elbow too high, annoying you to close the fridge or carry your groceries.
But why are so many of us feeling this discomfort after the injection?
What is going on in our arm that makes it feel so heavy a few hours after the bite?
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While all vaccines can cause this type of pain, the new RNA technology in Pfizer and Moderna vaccines is no stranger to this widespread side effect.
In question: the fatty envelope which contains the messenger RNA, the protein which will allow our body to learn to defend itself against the virus.
"The messenger RNA in itself is not very inflammatory, it is rather the lipids which are around the messenger RNA that create this inflammation", explains Stéphane Paul, immunologist at the University Hospital of St Etienne and member of the Covid vaccine committee -19.
Decryption in the video above to understand what is playing in our arm after the injection of the vaccine.