Human immunodeficiency virus (HIV)-infected children are more likely to develop severe varicella and to die when infected than otherwise healthy children.1 2 In the absence of universal immunisation varicella remains prevalent.3 Secondary prophylaxis in exposed high-risk patients is expensive, invasive, carries the risk of side-effects and may not be implemented reliably. Primary prophylaxis with live-attenuated varicella vaccine has been shown to be safe and immunogenic and effective against both primary varicella and zoster recurrences in HIV-infected children including those with moderate immunosuppression.4^–8

The Advisory Committee on Immunization Practices in the USA recommends the use of varicella vaccine in seronegative HIV-infected children with CD4 counts >15% and adolescents and adults with counts at or above 200 cells/mm3.9 The British HIV Association similarly recommends the vaccine for adults with counts >400 or >200 while on stable highly active antriretroviral therapy (HAART). There are no UK recommendations for children.

An emailed survey in March 2008 to senior clinicians in six UK centres managing children with HIV confirmed that there is virtually no use of the vaccine in this patient group at present.

Six HIV-infected children attending our clinic (aged 13 months to 7 years at time of immunisation) without previous history of clinical varicella or detected serum anti-varicella antibody by standard commercial immunoassay have received live-attenuated varicella vaccine without any adverse effects. Three were receiving HAART; the other three were treatment-naïve. All had CD4 counts >400cells/mm3 (range 418–1316), CD4 percentage >15% (range 19–35%) and plasma RNA viral load between <40 and 230 372 copies/ml. We offer two doses of vaccine at least 4 weeks apart (range 7–16 weeks in these cases) and we do not undertake post-immunisation serology. None of the children has subsequently developed chickenpox nor zoster or had known exposure to the wild virus (total time since last dose of vaccine 11.2 child-years at the time of writing).

Assessment for varicella immunisation should be a routine part of the management of children with HIV and clinical experience of use of the vaccine in this group and subsequent varicella and zoster episodes should be the subject of prospective national audit.