Effectiveness of Intramuscular Immunoglobulin in Unvaccinated Family Members After Household Measles Exposure

To the Editor—The efficacy of intramuscular immunoglobulin (IGIM) after measles exposure in patients weighing >30 kg may be decreased, because these patients may not receive an adequate dose of measles antibodies from the maximum dose. The Advisory Committee on Immunization Practices and the California Department of Public Health (CDPH) recommend IGIM for measles prophylaxis if it can be administered within 6 days of exposure [1, 2]. The CDPH recommends 0.5 mL/kg of IGIM with a maximal dose of 15 mL to unvaccinated children who weigh <30 kg. There is no recommendation to administer IGIM to persons weighing >30 kg, presumably because they may not receive a sufficient amount of measles antibodies from the maximum dose of 15 mL [2]. We report the effectiveness of IGIM after household exposure to measles in 2 unvaccinated family members weighing >30 kg.