7%; 95% confidence interval (CI) 69.2–84.8%] than by healthy individuals (88.0%; 95% CI 81.2–93.0%; P < 0.001) and did not increase after the second dose (69.8%; 95% CI 60.1–78.3%). Systemic reactions were rare and evenly distributed in the two groups (not shown). Ninety of 121 HIV-infected patients provided paired plasma samples for the detection of HIV RNA before and 4 weeks after the second dose of vaccine. At baseline, HIV RNA levels were below the detection threshold in 68 individuals and detectable

in 22. Unexpectedly, overall HIV RNA levels were significantly higher at follow-up compared with baseline (P < 0.001). HIV RNA was detected in 40 of 68 (58.8%) previously aviraemic patients [median 152 copies/mL; interquartile range (IQR) 87–509 copies/mL], independent of CD4 cell count (Fig. 1f). Among the 22 HIV-infected patients with buy RO4929097 detectable baseline HIV RNA levels (≥ 20 copies/mL), the median HIV RNA level increased, but an increase of ≥1 log10 copies/mL was observed in only two of 22 patients (9.1%). Individuals with an increase in their HIV RNA level were invited to return for follow-up 3 months later (median 91 days; IQR 65–122 days) at which point HIV RNA levels had returned to baseline in most individuals (27 of

34; 79.4%; Fig. 1f). Logistic regression analysis AG-014699 nmr established previous nonadjuvanted seasonal influenza Dimethyl sulfoxide vaccination as the sole determinant for HIV RNA increase above the detection threshold of 20 copies in previously aviraemic patients (P = 0.05; Table 4). Patients with a new elevated HIV RNA after dose 2 had similar characteristics compared with patients who stayed virologically suppressed: no differences in treatment regimen (NNRTI-based vs. PI-based antiretroviral therapy) were observed (data not

shown). In the following season (2010/2011), HIV RNA levels were assessed before and 4 weeks after administration of a single dose of seasonal influenza vaccine in a total of 66 HIV-positive patients who had participated in 2009. HIV RNA levels increased this time only weakly in three previously aviraemic individuals (median 29 copies/mL; range 20–125 copies/mL), two of whom had also experienced an increase after the AS03-adjuvanted vaccine in 2009 (23 and 125 copies/mL, respectively). For the remaining 23 individuals who had experienced an increase in viraemia in 2009, this finding was not reproduced in 2010/2011. This study reports the influence of the novel AS03-adjuvanted influenza A/09/H1N1 vaccine in HIV-positive patients attending an HIV clinic in a public hospital. HIV-positive patients achieved seroprotection rates of 94.2% and seroconversion rates of 85.6%, regardless of their clinical or biological characteristics. However, immunization triggered a detectable increase in HIV RNA levels even in successfully HAART-treated, aviraemic patients.