Qiuhan Gao

Publications of Qiuhan Gao

• Effectiveness of pandemic H1N1-2009 vaccination in reducing laboratory confirmed influenza infections among military recruits in tropical Singapore.

  Authors: Vernon J Lee, Chi Hsien Tan, Jonathan Yap, Alex R Cook, Pei-Jun Ting, Jin-Phang Loh, Qiuhan Gao, Mark I Chen, Wee Lee Kang, Boon Huan Tan, Paul A Tambyah

  PloS one. 01/2011; 6(10):e26572.

  Limited information is available about pandemic H1N1-2009 influenza vaccine effectiveness in tropical communities. We studied the effectiveness of a pandemic H1N1 vaccination program in reducingLimited information is available about pandemic H1N1-2009 influenza vaccine effectiveness in tropical communities. We studied the effectiveness of a pandemic H1N1 vaccination program in reducing influenza cases in Singapore. A surveillance study was conducted among military personnel presenting with febrile respiratory illness from mid-2009 to mid-2010. Consenting individuals underwent nasal washes, which were tested with RT-PCR and subtyped. A vaccination program (inactivated monovalent Panvax H1N1-2009 vaccine) was carried out among recruits. A Bayesian hierarchical model was used to quantify relative risks in the pre- and post-vaccination periods. An autoregressive generalised linear model (GLM) was developed to minimise confounding. Of 2858 participants, 437 (15.3%), 60 (2.1%), and 273 (9.6%) had pandemic H1N1, H3N2, and influenza B. The ratio of relative risks for pandemic H1N1 infection before and after vaccination for the recruit camp relative to other camps was 0.14 (0.016,0.49); for H3N2, 0.44 (0.035,1.8); and for influenza B, 18 (0.77,89). Using the GLM for the recruit camp, post-vaccination weekly cases decreased by 54% (37%,67%, p<0.001) from that expected without vaccination; influenza B increased by 66 times (9-479 times, p<0.001); with no statistical difference for H3N2 (p = 0.54). Pandemic vaccination reduced H1N1-2009 disease burden among military recruits. Routine seasonal influenza vaccination should be considered.

• A clinical diagnostic model for predicting influenza among young adult military personnel with febrile respiratory illness in Singapore.

  Authors: Vernon J Lee, Jonathan Yap, Alex R Cook, Chi Hsien Tan, Jin-Phang Loh, Wee-Hong Koh, Elizabeth A S Lim, Jasper C W Liaw, Janet S W Chew, Iqbal Hossain, Ka Wei Chan, Pei-Jun Ting, Sock-Hoon Ng, Qiuhan Gao, Paul M Kelly, Mark I Chen, Paul A Tambyah, Boon Huan Tan

  PloS one. 01/2011; 6(3):e17468.

  Influenza infections present with wide-ranging clinical features. We aim to compare the differences in presentation between influenza and non-influenza cases among those with febrile respiratoryInfluenza infections present with wide-ranging clinical features. We aim to compare the differences in presentation between influenza and non-influenza cases among those with febrile respiratory illness (FRI) to determine predictors of influenza infection. Personnel with FRI (defined as fever ≥ 37.5 °C, with cough or sore throat) were recruited from the sentinel surveillance system in the Singapore military. Nasal washes were collected, and tested using the Resplex II and additional PCR assays for etiological determination. Interviewer-administered questionnaires collected information on patient demographics and clinical features. Univariate comparison of the various parameters was conducted, with statistically significant parameters entered into a multivariate logistic regression model. The final multivariate model for influenza versus non-influenza cases was used to build a predictive probability clinical diagnostic model. 821 out of 2858 subjects recruited from 11 May 2009 to 25 Jun 2010 had influenza, of which 434 (52.9%) had 2009 influenza A (H1N1), 58 (7.1%) seasonal influenza A (H3N2) and 269 (32.8%) influenza B. Influenza-positive cases were significantly more likely to present with running nose, chills and rigors, ocular symptoms and higher temperature, and less likely with sore throat, photophobia, injected pharynx, and nausea/vomiting. Our clinical diagnostic model had a sensitivity of 65% (95% CI: 58%, 72%), specificity of 69% (95% CI: 62%, 75%), and overall accuracy of 68% (95% CI: 64%, 71%), performing significantly better than conventional influenza-like illness (ILI) criteria. Use of a clinical diagnostic model may help predict influenza better than the conventional ILI definition among young adults with FRI.

• Seroconversion and asymptomatic infections during oseltamivir prophylaxis against Influenza A H1N1 2009

  Authors: Vernon Lee, Jonathan Yap, Joshua Tay, Ian Barr, Qiuhan Gao, Hanley Ho, Boon Tan, Paul Kelly, Paul Tambyah, Anne Kelso, Mark Chen

  BMC Infectious Diseases. 01/2010;

  Abstract Background Anti-viral prophylaxis is used to prevent the transmission of influenza. We studied serological confirmation of 2009 Influenza A (H1N1) infections during oseltamivir prophylaxisAbstract Background Anti-viral prophylaxis is used to prevent the transmission of influenza. We studied serological confirmation of 2009 Influenza A (H1N1) infections during oseltamivir prophylaxis and after cessation of prophylaxis. Methods Between 22 Jun and 16 Jul 09, we performed a cohort study in 3 outbreaks in the Singapore military where post-exposure oseltamivir ring chemoprophylaxis (75 mg daily for 10 days) was administered. The entire cohort was screened by RT-PCR (with HA gene primers) using nasopharyngeal swabs three times a week. Three blood samples were taken for haemagglutination inhibition testing - at the start of outbreak, 2 weeks after completion of 10 day oseltamivir prophylaxis, and 3 weeks after the pandemic's peak in Singapore. Questionnaires were also administered to collect clinical symptoms. Results 237 personnel were included for analysis. The overall infection rate of 2009 Influenza A (H1N1) during the three outbreaks was 11.4% (27/237). This included 11 index cases and 16 personnel (7.1%) who developed four-fold or higher rise in antibody titres during oseltamivir prophylaxis. Of these 16 personnel, 8 (3.5%) were symptomatic while the remaining 8 personnel (3.5%) were asymptomatic and tested negative on PCR. Post-cessation of prophylaxis, an additional 23 (12.1%) seroconverted. There was no significant difference in mean fold-rise in GMT between those who seroconverted during and post-prophylaxis (11.3 vs 11.7, p = 0.888). No allergic, neuropsychiatric or other severe side-effects were noted. Conclusions Post-exposure oseltamivir prophylaxis reduced the rate of infection during outbreaks, and did not substantially increase subsequent infection rates upon cessation. Asymptomatic infections occur during prophylaxis, which may confer protection against future infection. Post-exposure prophylaxis is effective as a measure in mitigating pandemic influenza outbreaks.

• Seroconversion and asymptomatic infections during oseltamivir prophylaxis against Influenza A H1N1 2009.

  Authors: Vernon J Lee, Jonathan Yap, Joshua K Tay, Ian Barr, Qiuhan Gao, Hanley J Ho, Boon Huan Tan, Paul M Kelly, Paul A Tambyah, Anne Kelso, Mark I Chen

  BMC infectious diseases. 01/2010; 10:164.

  Anti-viral prophylaxis is used to prevent the transmission of influenza. We studied serological confirmation of 2009 Influenza A (H1N1) infections during oseltamivir prophylaxis and after cessationAnti-viral prophylaxis is used to prevent the transmission of influenza. We studied serological confirmation of 2009 Influenza A (H1N1) infections during oseltamivir prophylaxis and after cessation of prophylaxis. Between 22 Jun and 16 Jul 09, we performed a cohort study in 3 outbreaks in the Singapore military where post-exposure oseltamivir ring chemoprophylaxis (75 mg daily for 10 days) was administered. The entire cohort was screened by RT-PCR (with HA gene primers) using nasopharyngeal swabs three times a week. Three blood samples were taken for haemagglutination inhibition testing--at the start of outbreak, 2 weeks after completion of 10 day oseltamivir prophylaxis, and 3 weeks after the pandemic's peak in Singapore. Questionnaires were also administered to collect clinical symptoms. 237 personnel were included for analysis. The overall infection rate of 2009 Influenza A (H1N1) during the three outbreaks was 11.4% (27/237). This included 11 index cases and 16 personnel (7.1%) who developed four-fold or higher rise in antibody titres during oseltamivir prophylaxis. Of these 16 personnel, 8 (3.5%) were symptomatic while the remaining 8 personnel (3.5%) were asymptomatic and tested negative on PCR. Post-cessation of prophylaxis, an additional 23 (12.1%) seroconverted. There was no significant difference in mean fold-rise in GMT between those who seroconverted during and post-prophylaxis (11.3 vs 11.7, p = 0.888). No allergic, neuropsychiatric or other severe side-effects were noted. Post-exposure oseltamivir prophylaxis reduced the rate of infection during outbreaks, and did not substantially increase subsequent infection rates upon cessation. Asymptomatic infections occur during prophylaxis, which may confer protection against future infection. Post-exposure prophylaxis is effective as a measure in mitigating pandemic influenza outbreaks.