Measles reimmunization may not be effective in protecting HIV-infected children.

Abstract

To the Editors: We were interested to read the paper by Newman et al.1 They conclude that most HIV-infected children were not immune to measles and “might benefit from revaccination.” We agree that many HIV-infected children are not immune to measles, but revaccination may only benefit a proportion of these children. We have audited immunity to measles in HIV-infected children seen in our 3 centers in England. All children were reported to have been given measles vaccine as part of their routine childhood immunizations. Measles immunoglobulin G (IgG) was measured by enzyme-linked immunoassay. If measles IgG was not detected, children were given up to 2 doses of measles, mumps and rubella vaccine, if their CD4 count was >15%.2 Measles IgG was measured 6–12 weeks after vaccination to assess response. RESULTS Only 83 of 224 (37%) HIV-infected children in our clinics had detectable measles IgG, suggesting immunity to measles (Table 1). Twenty-four of the 141 nonimmune children were not subsequently immunized for a variety of reasons (CD4% <15%; moved away; and consent not obtained).TABLE 1: Numbers of HIV-Infected Children Tested for Measles Immunity at 3 English Centers and Response to VaccinationOf the 117 children who were revaccinated 74 (63%) responded; 59 of whom were receiving combination antiretroviral therapy (cART) with undetectable viral loads. Of the 35 nonresponders, 20 were not receiving cART and 25 had a detectable viral load. Sixty-five of 80 (81%) children receiving cART responded to measles vaccination compared with 9 of 29 (31%) not receiving cART. DISCUSSION Our audit also found a low prevalence of measles IgG seropositivity in HIV-infected children attending our clinics, despite a history of previous immunization. Previous studies have also shown that a substantial proportion of HIV-infected children are not immune to measles despite prior vaccination.3 Revaccination with measles vaccine is thus suggested. However, response to measles vaccine in HIV-infected children is poor in those not receiving cART.4 Response rates improve in those on cART, especially in older children with low HIV viral loads.4,5 We found that of those who could be immunized and those receiving cART with undetectable viral loads were more likely to respond. Despite assessment and reimmunization, only 157 children (70%) in our clinics are immune to measles. Documentation of measles immunization should be routine, but this is not enough to predict if HIV-infected children are immune to measles. Attention should focus on measuring measles immunity. We support the recent Paediatric European Network for Treatment of AIDS/Children’s HIV Association guidelines,2 which suggest that HIV-infected children should have measles serology measured to confirm immunity to measles. Those children who are nonimmune should be given one or more doses of measles, mumps and rubella vaccine, if they have a CD4% >15%. Response is much more likely if they are receiving cART and have an undetectable viral load. However, despite these measures, a substantial proportion of HIV-infected children will remain nonimmune to measles. Katie Rowson, RN Anton Tan, FRCPCH North Manchester General Hospital Manchester, United Kingdom Sheila Donaghy, RN Katja Doerholt, MD Paul Heath, MD St. George’s Healthcare NHS Trust London, United Kingdom Andrew Riordan, MD Alder Hey Children’s NHS Trust Liverpool, United Kingdom