Subcutaneous nodules: an important adverse event following immunization

ABSTRACT

Introduction: Subcutaneous nodules are a rare adverse event following immunization (AEFI). Reported cases have frequently been associated with aluminum-containing vaccines. Despite the development of a consensus definition of a subcutaneous nodule from the Brighton Collaboration in 2004, there continues to be variation in definitions used in published literature.

Areas covered: We reviewed the literature regarding subcutaneous nodule etiology, definition, clinical features, management, and approach to future immunizations. Embase and MEDLINE databases were searched with relevant MeSH terms initially on 8 November 2016, the same searches were repeated on 9 September 2018 prior to finalizing this review. We reviewed published case reports and larger studies reporting subcutaneous nodules and also reviewed articles discussing broader use of aluminum in immunizations and AEFIs.

Expert commentary: Consensus from clinicians regarding the approach to management of subcutaneous nodules is vital. We believe that the safety concerns regarding aluminum causing subcutaneous nodules are far outweighed by the benefits of vaccines containing aluminum. Ultimately, supporting subsequent immunizations in individuals that develop nodules needs to be a priority.

KEYWORDS:

• Adverse event following immunization
• immunization
• subcutaneous nodule
• vaccine

Article highlights

• Subcutaneous nodules are a rare adverse event following immunization (AEFI).

• Subcutaneous nodules have been frequently associated with aluminum-containing vaccines, along with variations in injection technique.

• Aluminum has been used as an adjuvant to increase vaccine response for many decades.

• Safety concerns regarding aluminum causing subcutaneous nodules are far outweighed by the benefits of vaccines containing aluminum.

• Clinical management of subcutaneous nodules is varied, but a priority should be ensuring subsequent immunizations are supported.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Supplementary material

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Additional information

Funding

This paper was not funded.