Using Clinical Research Networks to Assess Severity of an Emerging Influenza Pandemic.

Background: Early clinical severity assessments during the 2009 influenza A H1N1 pandemic (pH1N1) overestimated clinical severity due to selection bias and other factors. We retrospectively investigated how to use data from the International Network for Strategic Initiatives in Global HIV Trials, a global clinical influenza research network, to make more accurate case fatality ratio (CFR) estimates early in a future pandemic, an essential part of pandemic response. Methods: We estimated the CFR of medically attended influenza (CFRMA) as the product of probability of hospitalization given confirmed outpatient influenza and the probability of death given hospitalization with confirmed influenza for the pandemic (2009-2011) and post-pandemic (2012-2015) periods. We used literature survey results on health-seeking behavior to convert that estimate to CFR among all infected persons (CFRAR). Results: During the pandemic period, 5.0% (3.1%-6.9%) of 561 pH1N1-positive outpatients were hospitalized. Of 282 pH1N1-positive inpatients, 8.5% (5.7%-12.6%) died. CFRMA for pH1N1 was 0.4% (0.2%-0.6%) in the pandemic period 2009-2011 but declined 5-fold in young adults during the post-pandemic period compared to the level of seasonal influenza in the post-pandemic period 2012-2015. CFR for influenza-negative patients did not change over time. We estimated the 2009 pandemic CFRAR to be 0.025%, 16-fold lower than CFRMA. Conclusions: Data from a clinical research network yielded accurate pandemic severity estimates, including increased severity among younger people. Going forward, clinical research networks with a global presence and standardized protocols would substantially aid rapid assessment of clinical severity. Clinical Trials Registration: NCT01056354 and NCT01056185

Effect of intermittent interleukin-2 therapy on CD4+ T-cell counts following antiretroviral cessation in patients with HIV.

BACKGROUND: Interleukin (IL)-2 therapy impacts T-cell homeostasis. Whether IL-2 expanded CD4(+) T cells may persist following viral rebound has not been fully investigated. METHODS: Patients with CD4(+) T cells 500/µl or more and HIV RNA less than 50 copies/ml were randomized to continue antiretroviral therapy (ART) either alone (n = 67) or combined with three IL-2 cycles (n = 81; 6 million units) twice daily for 5 days at weeks 0, 8, and 16 before stopping ART (week 24). Patients were followed up to 168 weeks. RESULTS: At week 24, median CD4(+) T-cell counts were 1198 and 703 cells/µl in the IL-2 and control groups, respectively (P < 0.001). At week 72, 27% (IL-2 group) and 45% (control group; P = 0.03) of patients were in failure (defined as no interruption of ART at week 24, CD4 drop below 350 cells/µl or ART resumption). After week 24, a biphasic decline (before and after week 32) of CD4 was noted -106 and -7 cells/µl per month in controls and -234 and -17 in IL-2 group (all P ≤ 0.0001). At week 96, IL-2-expanded CD4(+)CD25(+) T cells remained higher than in the control group (26 vs. 16%, P = 0.006). CONCLUSION: In IL-2-treated patients, CD4(+)CD25(+) T cells persisting despite viral replication allow a longer period of ART interruption.