Abstract Body

We sought to determine if standard influenza and pneumococcus vaccines can be used to stimulate HIV reservoirs during suppressive antiretroviral therapy (ART).

Persons with HIV infection on suppressive ART (N=54) were enrolled in a randomized, double-blinded, placebo-controlled, cross-over trial of two clinically recommended vaccines. For three cycles, Placebo, Pneumovax®23, and Fluarix® vaccines were administered in random blinded order with a minimum 8-week wash-out period between administrations. Blood was collected at baseline and days 2, 4, 7, 14 and 30 post immunization. Levels of total cellular HIV RNA and HIV DNA were measured by droplet digital (dd)PCR. For the primary outcome, a paired-sample t-test compared differences in changes in level of CD4+ T-cell-associated HIV RNA levels from baseline to day 7 post-injection between each vaccine and placebo. We performed similar comparisons on remaining timepoints (days 2, 4, 14 and 30) and on HIV DNA levels for secondary outcomes.

Fifty-three participants completed at least one cycle and there were no serious adverse events related to the intervention. Mean age was 45 years (standard deviation [SD]: 11); 45 (83%) were men (sex at birth) and 19 (35%) were white, 23 (43%) Hispanic and 12 (22.2%) of mixed race/ethnicity. Mean CD4+ T-cells at randomization were 753 cells/?l (SD: 249). Overall, we observed no significant differences in cellular HIV RNA transcription for either of the two vaccines compared to placebo from baseline to day 7 (Pneumovax®23 [mean difference: -999 (95%CI: -3007,1009), n=35, p=0.32] and Fluarix® [mean difference: -334 (95% CI: -1136,468), n=40, p=0.40], Figure 1 Panel A). Similarly, we did not observe significant differences in changes from baseline to days 2, 4, 14 or 30 for cellular HIV RNA levels, Figure 1 Panel B. We observed a significant transient increase in cellular HIV DNA levels when comparing changes from baseline for Pneumovax®23 to change from baseline for placebo injections at days 2 and 4 after vaccine administration (Day 2: 41 [95%CI: 4,78], p=0.03, n=33, Day 4: 78 [95%CI: 1,155], p=0.0485, n=8) but not at days 7, 14 or 30 and none for Fluarix®, Figure 1 Panels C and D.

Clinically recommended vaccines appear safe but did not stimulate the immune system strongly enough to elicit significantly noticeable cellular HIV transcription during ART.