Can supraclavicular lymph nodes react and swell after a vaccine like the COVID one?

Yes, lymph nodes in the supraclavicular area can react and swell after receiving a vaccine like the COVID-19 vaccine. This is because lymph nodes are clusters of white blood cells and vaccines work to strengthen/activate our immune system. Swelling of the lymph nodes can be a minor side effect and is a sign that your immune system is responding. Some people may also experience this phenomenon when they have certain infections. Before receiving the vaccine, you may have had lymph nodes in the same areas, but you may have never noticed them because they had never swollen before.