The occurrence of lymphadenopathy following vaccination has been described as a rare adverse reaction (≥1/1000 to<1/100) following mRNA vaccines. In general, vaccination-related lymphadenopathies are usually in axillary localization, being supraclavicular localization much more infrequent.
An incorrect vaccine administration technique could be influencing the occurrence of supraclavicular lymphadenopathies, as it has been observed that vaccine drainage tends to ascend to the supraclavicular nodes when the vaccine is administered in the area near the shoulder and not in the center of the deltoid triangle.
Supraclavicular lymphadenopathies appearing up to 10 days after vaccination are inflammatory and tend to resolve spontaneously after 7 days from the date of their appearance in most of the cases. No complementary tests (blood tests, biopsies or computed axial tomography) are necessary, nor do they require any specific pharmacological or physical treatment. In case of acute onset of supraclavicular lymphadenopathy after vaccination with a mRNA based COVID-19 vaccine, this possibility of transient and benign self-limited vaccine-related adverse reaction should be considered.
- The occurrence of lymphadenopathy following vaccination has been described as a rare adverse reaction (≥1/1000 to<1/100) following mRNA vaccines.
 Fernández-Prada M, Rivero-Calle I, Calvache-González A, Martinón-Torres F. Acute onset supraclavicular lymphadenopathy coinciding with intramuscular mRNA vaccination against COVID-19 may be related to vaccine injection technique, Spain, January and February 2021. Euro Surveill. 2021 Mar;26(10):2100193. doi: 10.2807/1560-7917.ES.2021.26.10.2100193. PMID: 33706861; PMCID: PMC7953532.