Immunoglobulin Use, Availability, and Administration Considerations in Measles Prevention.

In 2026, the National Foundation for Infectious Diseases (NFID), with the Infectious Diseases Society of America (IDSA), convened a Measles Summit in response to the largest U.S. measles resurgence in over three decades, with more than 3,000 confirmed cases mostly among unvaccinated individuals. Many clinicians and public health professionals have limited firsthand measles experience, underscoring the need for clinical guidance. In this commentary, we examine immune globulin (IG) use for measles post-exposure prophylaxis (PEP) amid fragile supply and logistical challenges. GamaSTAN®, the sole Food and Drug Administration (FDA)-licensed intramuscular IG product, faces episodic availability, non-returnable single-vial economics, and a 2013 recommendation to double the PEP dose, increasing per-patient demand. IVIG is increasingly employed when patients weigh 30 kg or more, beyond the weight at which an adequate dose of immune globulin can be given intramuscularly, or when IMIG supply is constrained, while concurrent lot withdrawals compromise institutional formularies. We review evidence-based patient selection for PEP, emphasizing that the Measles, Mumps, and Rubella (MMR) vaccine remains first-line within 72 hours of exposure, with IG reserved when vaccination is contraindicated or potentially ineffective. Immunosuppressive therapies vary widely in their effects on the safety and efficacy of live vaccines. We therefore argue against categorizing every biologic, immunomodulator, or steroid as an automatic MMR contraindication, which would overestimate IG-PEP demand and preclude MMR for eligible patients. We propose class-specific stratification and an electronic health record decision-support rule to better align IG demand with genuine need. Finally, we address declining potency standards for measles antibody, attributable to waning donor titers, and offer guidance on dosing, multi-site pediatric administration, and infusion logistics within the PEP window.