Why Does the COVID-19 Vaccine Cause a Sore Arm?

Having a sore arm after getting vaccinated is a common side effect. For some people, it resolves on its own and for some, it can be troublesome and need treatment to reduce the discomfort. Post-vaccination, the site of injection- where the vaccine is administered can turn sore, pain, or sometimes even swell up due to inflammation. It has now been actually referred to as the ‘COVID arm’.

But why does the arm hurt? 

There can be many side effects of vaccines, but the most common one is a pain in the arm where you get jabbed. There can be few other side effects like experiencing soreness, stiffness, difficulty in moving the arm. But what is the reason for the pain?

The pain and tenderness at the site of injection are actually one of the first side effects that show up when you get the vaccine jab. It also is part of the localized response when you get vaccinated, i.e. the effects which kick in at the exact spot where the jab is given.

According to medical experts, a sore arm after the COVID -19 vaccine is a sign that your body is reacting as expected. Your immunity is working as it should. 

For some people, these side effects are worse with the second shot, compared to the first one. But that is completely normal and you can feel good that your immunity is strong. 

What causes a sore arm? 

The Covid-19 vaccine shot is given via intramuscular injections which is directly injected into the arm muscle. The vaccine triggers inflammation at the site where the shot is administered which indicates that your immunity is being activated. 

The reaction that makes the arm sore is an example of how the body perceives the vaccine to be. At first, the body considers it to be an injury like a cut or bleed and sends immune cells to the arm and relaxes the blood vessels. And as a part of the process, the immune cells cause inflammation. Apart from soreness, some people can also experience redness, irritation, and swelling near the injection site.  

How long will the soreness last?

Most vaccination side-effects tend to last for 2-3 days and the same goes for arm soreness. The soreness could stretch for up to 5 days post-vaccination, like in my case. 

Though there are some ways to make it better like keep your arm moving to stimulate blood flow to the area, this will reduce the soreness. You can also apply some cool compress to ease the pain.

Well, having arm soreness is nothing to worry about.  A vaccine is certainly supposed to prompt inflammation in the body and create antibodies. If you do experience high levels of inflammation, it is supposed to be a good sign that your vaccine is doing its job and you are getting the required protection.