Subcutaneous nodules: an important adverse event following immunization.

Area of Science:

• Immunology
• Vaccinology
• Dermatology

Background:

• Subcutaneous nodules are a rare adverse event following immunization (AEFI).
• Cases are frequently associated with aluminum-containing vaccines.
• Varied definitions of subcutaneous nodules persist despite a 2004 consensus.

Purpose of the Study:

• To review the literature on subcutaneous nodule etiology, definition, clinical features, and management.
• To discuss the approach to future immunizations in individuals who develop nodules.
• To provide expert commentary on the clinical consensus for managing subcutaneous nodules.

Main Methods:

• Literature search of Embase and MEDLINE databases using relevant MeSH terms.
• Searches conducted initially on November 8, 2016, and repeated on September 9, 2018.
• Review of published case reports, larger studies, and articles on aluminum in immunizations and AEFIs.

Main Results:

• Subcutaneous nodules are a rare but reported adverse event following immunization.
• Aluminum-containing vaccines are frequently implicated in reported cases.
• Literature review highlights variations in nodule definitions and clinical management.

Conclusions:

• Consensus among clinicians on managing subcutaneous nodules is crucial.
• The benefits of aluminum-adjuvanted vaccines outweigh the safety concerns of subcutaneous nodules.
• Prioritizing subsequent immunizations for individuals who develop nodules is essential.