I had a sore and stiff neck for the better part of two days after I received my first Pfizer-BioNTech COVID-19 vaccine [1] (a few hours post-vaccination, I raised my arms to put my hair up and felt a sort of twinge in my neck). For transparency's sake, as of this article's publishing, I am one week out from my second dose. The other side effects I experienced were headache and tiredness, but it wasn't anything I couldn't handle with some rest, hydration, and Tylenol [2]. I hadn't heard of stiff neck specifically as a common COVID-19 vaccine side effect [3]; however, with a simple search on Twitter, I did find similar anecdotes from people who had gotten the vaccines, and after speaking with two experts in the field of allergy and immunology, I learned that this could very well be a normal response.
Swollen lymph nodes are a reported side effect due to the COVID-19 vaccines (you might have read about swollen or tender lymph nodes under the armpit in particular [4] that, for example, affected 11.6 percent of Moderna clinical trial participants after the first dose [5] and 16 percent following the second dose). It's an expected side effect of any vaccine and shows that your immune cells in your lymph nodes are working. The reaction also typically occurs on the same side of the body that the vaccine was administered, but Sofija Volertas [6], MD, an assistant professor in UNC's Division of Rheumatology, Allergy, and Immunology, told POPSUGAR that the lymph node swelling could be on both sides of your body (though is more likely on the side where you got the injection in your arm).
The stiffness and soreness I experienced was exclusive to the left side of my neck, which is consistent with the fact that I got the COVID-19 shot on my left arm. Dr. Volertas explained that in addition to your armpits, you have lymph nodes running in your neck, along your collarbone, and behind your ears. "Lymph nodes are where your immune cells live, and so [the soreness and swelling] just means that they're getting activated in doing what we want them to be doing," she said. Amina Abdeldaim [8], MD, MPH, Medical Director for allergy brand and service Picnic [9], agreed, stating that my cervical lymph nodes, found on the side of the neck, were likely inflamed.
Swelling in certain lymph nodes, Dr. Volertas said, can make the muscles around that area a little more tense and tight and can result in stiffness. She added that another cause of neck stiffness could have been that I was favouring my left arm because it was sore (injection site and arm soreness is common, and I experienced it for a number of days myself). "That in and of itself may have caused a muscle tweak or some tension," she said. "And if you're holding your body in a slightly different way than you would normally, that could contribute potentially as well."
Body and muscle aches, too, is also a common side effect of the COVID-19 vaccine, Dr. Volertas reminded me. It's worth noting that other factors could have been at work leading up to the vaccine, such as how I slept the night before and how tense I was at my home work space (I tend to slouch a lot [10]). That said, I didn't notice how stiff my neck felt until hours after my vaccine. And, my coworker who regularly experiences TMJ disorder [11] and a stiff neck revealed that, after receiving the first dose of the Moderna COVID-19 vaccine, TMJ pain as well as neck and trap muscle stiffness seemed to increase in severity later that day, lasting about 24 to 36 hours.
Remember, side effects to the COVID vaccines are normal, typically short-lived, and begin within a day or two of getting your shot [13]. As for severity of those side effects, your age may come into play [14] along with which dose you're receiving — second doses of the mRNA vaccine tend to affect people moreso than the first. Most importantly, side effects (within reason) are positive. As Dr. Abdeldaim said, "I don't want to say you should be happy that you feel certain things, but the vaccine has to interact with your immune system." It's doing its job.
POPSUGAR aims to give you the most accurate and up-to-date information about the coronavirus, but details and recommendations about this pandemic may have changed since publication. For the latest information on COVID-19, please check out resources from the WHO [15], the CDC [16], and local public health departments [17].