Comparative epidemiology of pandemic and seasonal influenza A in households.

BACKGROUND: There are few data on the comparative epidemiology and virology of the pandemic 2009 influenza A (H1N1) virus and cocirculating seasonal influenza A viruses in community settings. METHODS: We recruited 348 index patients with acute respiratory illness from 14 outpatient clinics in Hong Kong in July and August 2009. We then prospectively followed household members of 99 patients who tested positive for influenza A virus on rapid diagnostic testing. We collected nasal and throat swabs from all household members at three home visits within 7 days for testing by means of quantitative reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay and viral culture. Using hemagglutination-inhibition and viral-neutralization assays, we tested baseline and convalescent serum samples from a subgroup of patients for antibody responses to the pandemic and seasonal influenza A viruses. RESULTS: Secondary attack rates (as confirmed on RT-PCR assay) among household contacts of index patients were similar for the pandemic influenza virus (8%; 95% confidence interval [CI], 3 to 14) and seasonal influenza viruses (9%; 95% CI, 5 to 15). The patterns of viral shedding and the course of illness among index patients were also similar for the pandemic and seasonal influenza viruses. In a subgroup of patients for whom baseline and convalescent serum samples were available, 36% of household contacts who had serologic evidence of pandemic influenza virus infection did not shed detectable virus or report illness. CONCLUSIONS: Pandemic 2009 H1N1 virus has characteristics that are broadly similar to those of seasonal influenza A viruses in terms of rates of viral shedding, clinical illness, and transmissibility in the household setting.

Outcomes and prognostic factors in 267 patients with severe acute respiratory syndrome in Hong Kong.

BACKGROUND: Severe acute respiratory syndrome (SARS) has become a global public health emergency. OBJECTIVE: To evaluate the characteristics and outcomes of patients with SARS in Hong Kong and to identify predictors of mortality. DESIGN: Retrospective cohort study. SETTING: Quarantine hospital for patients with SARS in Hong Kong. PATIENTS: 267 consecutive patients hospitalized from 26 February to 31 March 2003 for probable or confirmed SARS. MEASUREMENTS: Clinical, laboratory, and radiographic measures; 3-month mortality rate. RESULTS: According to our case definition, there were 227 cases of confirmed SARS and 40 cases of probable SARS. Common presenting symptoms were fever (99% of patients), chills (74%), malaise (63%), and myalgia (50%). Laboratory findings included lymphopenia (73%), thrombocytopenia (50%), hyponatremia (60%), and elevated levels of lactate dehydrogenase (47%) and C-reactive protein (75%). During hospitalization, incidence of diarrhea (53%), anemia (53%), and acute renal failure (6%) increased. Sixty-nine patients (26%) required intensive care because of respiratory failure. The 3-month mortality rate was 12% (95% CI, 8% to 16%). Factors contributing to mortality were respiratory failure, acute renal failure, and nosocomial sepsis. On multivariate Cox regression, age older than 60 years (relative risk, 5.10 [CI, 2.30 to 11.31]; P < 0.001) and lactate dehydrogenase level greater than 3.8 micro kat/L at presentation (relative risk, 2.20 [CI, 1.03 to 4.71]; P = 0.04) were independent predictors of mortality. CONCLUSION: Because of the longer follow-up period in our cohort, the mortality rate in these patients is higher than rates reported in previous studies. Advanced age and high lactate dehydrogenase level at presentation predict mortality. *For members of the Princess Margaret Hospital SARS Study Group, see the Appendix.

Value of initial chest radiographs for predicting clinical outcomes in patients with severe acute respiratory syndrome.

PURPOSE: To determine whether the initial chest radiograph is helpful in predicting the clinical outcome of patients with severe acute respiratory syndrome (SARS). METHODS: Of 343 patients who met the World Health Organization's case definition of probable SARS and who had been admitted to a regional hospital in Hong Kong, 201 patients had laboratory evidence of SARS coronavirus infection. The initial frontal chest radiographs of these 201 patients were assessed in a blinded fashion by 3 radiologists; individual findings were accepted if at least 2 of the radiologists concurred. Independent predictors of an adverse outcome, defined as the need for assisted ventilation, death, or both, were identified by multivariate analysis. RESULTS: Bilateral disease and involvement of more than two zones on the initial chest radiograph were associated with a higher risk of liver impairment and poor clinical outcome. Forty-two patients (21%) developed an adverse outcome. Multivariate analysis showed that lung involvement of more than two zones (odds ratio [OR] = 7.0; 95% confidence interval [CI]: 2.7 to 17.9), older age (OR for each decade of life = 1.5; 95% CI: 1.1 to 2.0), and shortness of breath on admission (OR = 2.8; 95% CI: 1.1 to 7.4) were independent predictors of an adverse outcome. CONCLUSION: Frontal chest radiographs on presentation may have prognostic value in patients with SARS.

Adjustment outcomes in Chinese patients following one-month recovery from severe acute respiratory syndrome in Hong Kong.

This study aimed to examine the short-term adjustment outcomes including distress, self-esteem, and quality of life among Chinese patients after 1-month recovery from severe acute respiratory syndrome (SARS) in Hong Kong and to investigate the predictive abilities of a set of selected variables on the outcomes. At 1-month recovery, 100 SARS survivors (mean age = 37; 66 women) and 184 community subjects completed self-administered questionnaires. In the General Health Questionnaire-28, 61% of the SARS survivors were identified as distressed cases under a conservative cutoff score of 6. Compared with the community sample, SARS survivors had significantly more distress and poor quality of life. Being a healthcare worker, severity of SARS symptoms, steroid dosage, and social support accounted for a portion of variances of different measures. Early psychiatric screening and intervention may be beneficial for the adjustment of SARS survivors after short-term recovery. Future research on the long-term impact of SARS is recommended.