Having a sore arm for a couple of days after your COVID-19 vaccination is a pretty common side effect
One guy on TikTok @justlydeserved, who often shares about all things science-related, explains the reason why this probably happens.
After you get vaccinated, he says that about a billion muscle cells in your shoulder are being instructed to churn out as many spike proteins as they can.
Spike proteins are harmless and are found on the surface of the COVID-19 virus, according to Centers For Disease Control And Prevention.
As a result, he says that "your body is freaking out that there are a bunch of spike proteins in your arm" and your immune system is figuring out how to create antibodies to fight them
In other words, your immune system is trying to find ways to protect you from the virus.
While your body is going through that, it is also creating a general immune response in that area like increasing blood flow and temperature in your arm.
"It's also triggering all of your pain receptors in that area because your body is just saying, 'Don't move until we figure out what the hell is going on here'," he adds.
However, even if you do not or did not experience any soreness, it does not mean that there is something wrong
He replied in the comments that different people may have different side effects. Some get fever and chills, while others do not feel a thing. Some might get a sore arm while others may not.
Soreness is an indication that your immune system is working but even if you do not experience it, don't worry because different bodies function differently.
So why does the second dose of vaccination produce a more intense reaction in many cases?
In reply to another person's question, he explains that it's because your body recognises those spike proteins and "mounts a generalised immune response".
The COVID-19 vaccines "trick the body's immune system to think it's being invaded by the virus", explains infectious disease expert Aline M Holmes to Verywell Health. So your body sends white blood cells to fight off the "intruder".
To soothe the soreness, experts suggest doing gentle movements or placing a cold compress on the area.