[Influenza vaccination in HIV infected children: immunologic and viral load changes]

To identify whether influenza immunization in HIV infected children could increase HIV viral load and decrease CD4+ lymphocytes count as a consequence of the response induced by a T cell-dependent antigen.

Prospective, descriptive study, with 51 HIV infected children, vaccinated against influenza in 1999, in Florianópolis, Brazil. Blood samples were collected at three different moments: on the immunization day; between 14 and 20 days later; between 60 and 90 days later. Plasma levels of HIV viral load and CD4+ lymphocytes count were determined. Friedman ANOVA test, Student t test for dependent samples, Bonferroni correction and Wilcoxon matched test were performed for statistical analysis.

Children's mean age was 6.08 years (1 to 12.9 years). The medians of CD4+ lymphocyte count on vaccination day and at the other two moments were 789, 645 and 768 cells/mm(3), respectively. A significant reduction was observed in the CD4+ lymphocyte count between the first and the second analyses, but the same did not happen between the first and the third analyses. There was no significant difference of CD4+ lymphocyte percentage between the first and the second analyses. The median of HIV viral load values in log10 copies/ml was 4.38, 4.30 and 4.25, at the three moments respectively. Eight out of 44 patients (18.2%) showed increase > or =0.5 log 10 copies/ml in HIV viral load between the first and the second analysis and among these, four returned to levels close to their base levels in the third analysis.

There was no significant change in the CD4+ lymphocyte percentage, in spite of a transitory increase in HIV viral load after influenza vaccination. Caution should be used when administering vaccine against flu to children with no stable clinical and immunological conditions, mainly if they are not under effective anti-retroviral therapeutics.