Background: HIV-1-infected children have an increased risk of severe chickenpox. However, vaccination is not recommended in severely immunocompromised children.
Objective: Can the live-attenuated varicella zoster virus (VZV) Oka strain be safely and effectively given to HIV-1-infected children despite previously low CD4 T-cell counts?
Methods: VZV vaccine was administered twice to 15 VZV-seronegative HIV-1-infected children when total lymphocyte counts were greater than 700 lymphocytes/μl, and six HIV-negative VZV-seronegative siblings. Weekly clinical follow-up and sampling were performed.
Results: None of the children developed any clinical symptom or serious adverse reaction after immunization. Only nine (60%) of the HIV-1-infected children had VZV-specific antibodies after two immunizations, whereas 100% of the siblings seroconverted. Age at baseline was negatively correlated with the VZV IgG titre at 6 weeks after the second vaccination in HIV-1-infected children. VZV-specific antibody titres after two immunizations were at a similar level to those found after wild-type infection in non-vaccinated HIV-1-infected patients, but significantly lower than in HIV-negative siblings. Importantly, VZV-specific T-cell responses increased after vaccination and were comparable in both groups over time. Documented wild-type VZV contact in three vaccinated patients did not result in breakthrough infections.
Conclusion: VZV vaccination of previously immunocompromised HIV-1-infected children was safe. Vaccination induced specific immune responses in some of the vaccinated HIV-1-infected children, suggesting that previously immunocompromised individuals are protected against severe forms of varicella.
From the aEmma Children's Hospital, the Netherlands
bDepartments of Clinical Viro-Immunology, Sanquin Research and Landsteiner Laboratory, the Netherlands
cMedical Microbiology, Section of Clinical Virology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
dDepartment of Immunology, Universitair Medisch Centrum Utrecht, Utrecht, the Netherlands.
Received 28 March, 2006
Revised 14 August, 2006
Accepted 25 September, 2006
Correspondence to Taco W. Kuijpers, Emma Children's Hospital, Academic Medical Center, Room G8-205, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands. Tel: +31 20 5662727; fax: +31 20 6917735; e-mail: email@example.com