Influenza A H1N1 in HIV-infected adults

Objectives

HIV‐infected adults are considered to be at higher risk for influenza A H1N1 complications but data supporting this belief are lacking. We aimed to compare epidemiological data, clinical characteristics, and outcomes of influenza A H1N1 infection between HIV‐infected and ‐uninfected adults.

Methods

From 26 April to 6 December 2009, each adult presenting with acute respiratory illness at the emergency department of our institution was considered for an influenza A H1N1 diagnosis by specific multiplex real‐time polymerase chain reaction. For every HIV‐infected adult diagnosed, three consecutive adults not known to be HIV‐infected diagnosed in the same calendar week were randomly chosen as controls.

Results

Among 2106 adults tested, 623 (30%) had influenza A H1N1 infection confirmed. Fifty‐six (9%) were HIV‐positive and were compared with 168 HIV‐negative controls. Relative to HIV‐negative controls, HIV‐positive patients were older, more frequently male, and more frequently smokers (P≤0.02). In the HIV‐positive group, prior or current AIDS‐defining events were reported for 30% of patients, 9% and 30% had CD4 counts of <200 and 200–500 cells/μL, respectively, and 95% had HIV‐1 RNA <50 copies/mL. Pneumonia (9%vs. 25%, respectively, in the HIV‐positive and HIV‐negative groups; P=0.01) and respiratory failure (9%vs. 21%, respectively; P=0.04) were less common in the HIV‐positive group. Oseltamivir (95%vs. 71% in the HIV‐positive and HIV‐negative groups, respectively; P=0.003) was administered more often in HIV‐positive patients. Three patients (all HIV‐negative) died. In the HIV‐positive group, CD4 cell count and plasma HIV‐1 RNA did not differ before and 4–6 weeks after influenza A H1N1 diagnosis (P>0.05).

Conclusions

HIV infection did not increase the severity of influenza A H1N1 infection, and influenza A H1N1 infection did not have a major effect on HIV infection.