Search

A prospective study among adults hospitalized for polymerase chain reaction–confirmed respiratory syncytial virus infections (n = 123) showed frequent occurrence of lower respiratory-tract complications causing respiratory insufficiency (52.8%), requirement for assisted ventilation (16.3%), and intensive care unit admission/death (12.2%). High viral RNA concentration was detected at time of hospitalization, including in patients who presented later than 2 days of illness (day 1–2, 7.29 ± 1.47; day 3–4, 7.28 ± 1.41; day 5–8, 6.66 ± 1.87 log10 copies/mL). RNA concentration was independently associated with risk of complications and respiratory insufficiency (adjusted odds ratio 1.40 per log10 copies/mL increase, 95% confidence interval, 1.03–1.90; P = .034). Our data indicate the need and provide a basis for clinical research on antiviral therapy in this population.

Background It is unclear if higher-dose oseltamivir provides benefit beyond the standard dose in influenza patients who require hospitalization. Methods A prospective intervention study was performed in 2 acute care general hospitals in Hong Kong over 4 seasonal peaks (2010-2012). Adults (≥18 years) with laboratory-confirmed influenza (85 A/H3N2, 34 A/H1N1pdm09, 36 B) infections who presented within 96 hours were recruited. Study regimen of either 150 mg or 75 mg oseltamivir twice daily for 5 days was allocated by site, which was switched after 2 seasons. Subjects with preexisting renal impairment (creatinine clearance, 40-60 mL/minute) received 75 mg oseltamivir twice daily. Viral clearance by day 5 and clinical responses were compared between groups. Plasma steady-state trough oseltamivir carboxylate (OC) concentration was measured by high-performance liquid chromatography-tandem mass spectrometry. Results Altogether, 41 and 114 patients received 150 mg and 75 mg twice-daily oseltamivir, respectively; their enrollment characteristics (mean age, 61 ± 18 vs 66 ± 16 years) and illness severity were comparable. Trough OC levels were higher in the 150-mg group (501.0 ± 237.0 vs 342.6 ± 192.7 ng/mL). There were no significant differences in day 5 viral RNA (44.7% vs 40.2%) or culture negativity (100.0% vs 98.1%), RNA decline rate, and durations of fever, oxygen supplementation, and hospitalization. Results were similar when analyzed by study arm (all cases and among those without renal impairment). Subanalysis of influenza B patients showed faster RNA decline rate (analysis of variance, F = 4.14; P = .05) and clearance (day 5, 80.0% vs 57.1%) with higher-dose treatment. No oseltamivir resistance was found. Treatments were generally well tolerated. Conclusions We found no additional benefit of higher-dose oseltamivir treatment in adults hospitalized with influenza A, but an improved virologic response in influenza B. Clinical trials registration ClinicalTrials.gov, NCT01052961.

BACKGROUND A need for quadrivalent vaccines to cover both lineages of influenza B has been raised. Information on the circulation status of influenza B lineages and the associated hospitalization rates is important to assist evidence-based decision making. This retrospective study revealed the situation in a subtropical city over a 10-year period. METHODS Sequences of 268 influenza B isolates were analyzed to identify the circulating pool of virus lineages for each year. Hospital records and population census data were used to estimate annual age-specific hospitalization rates. RESULTS Cocirculation with 2 influenza B lineages was found in 9 of the 10 years. Only in 6 of the 10 years had the vaccine strain successfully matched with the lineage that was found in >50% of the circulating pool. Six years were predominated by one lineage (occupying >80% of the circulating pool), and these years had higher (average, 1.4-fold) hospitalization rates. Matching between vaccine and circulating lineage was achieved only in 2 of the 6 "predominated years." The Yamagata lineage accounted for most (5/6) of the predominated years. Overall, 24% of influenza admissions were due to influenza B, and influenza B contributed to a higher proportion (41.9%) among children and young teenagers (5-14 years old). CONCLUSIONS Cocirculation with 2 influenza B lineages is common in the subtropical region. To predict the next predominant lineage proves to be difficult. Influenza B accounts for a substantial fraction of influenza-associated hospitalizations, especially among children and young teenagers. Quadrivalent vaccines may improve the effectiveness of influenza vaccination programs.

It is unclear whether pandemic 2009 influenza A (pH1N1) infection caused more significant disease among hospitalized adults than seasonal influenza.A prospective, observational study was conducted in adults hospitalized with polymerase chain reaction-confirmed pH1N1 infection in 2 acute-care general hospitals from June 2009 to May 2010 (n = 382). Complications and outcomes were described and compared with those in a seasonal influenza cohort (2007-2008, same hospitals; n = 754).Hospitalized patients with pH1N1 influenza were younger than those with seasonal influenza (mean age ± standard deviation, 47 ± 20 vs 70 ± 19 years) and fewer had comorbid conditions (48% vs 64%). The rate of positive immunofluorescence assay results was low (54% vs 84%), and antiviral use was frequent (96% vs 52%). Most patients in both cohorts developed complicated illnesses (67.8% vs 77.1%), but patients with pH1N1 influenza had higher rates of extrapulmonary complications (23% vs 16%; P = .004) and intensive care unit admission and/or death (patient age35 years, 2.3% vs 0%; 35-65 years, 12.4% vs 3.2%;65 years, 13.5% vs 8.5%; adjusted odds ratio [OR] 2.13; 95% confidence interval [CI], 1.25-3.62; P = .005). Patients who received antiviral treatment within 96 h after onset had better survival (log-rank test, P.001). However, without timely treatment, the mortality risk was higher with pH1N1 infection (9.0% vs 5.8% for seasonal influenza; adjusted OR, 6.85; 95% CI, 1.64-28.65; P = .008]. Bacterial superinfection worsened outcomes.Adults hospitalized for pH1N1 influenza had significant complications and mortality despite being younger than patients with seasonal influenza. Antiviral treatment within 96 h may improve survival.