Tawee Chotpitayasunondh

Clinical aspects of pandemic 2009 influenza a (H1N1) virus infection

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Update on avian influenza A (H5N1) virus infection in humans.

The members of the writing committee (Abdel-Nasser Abdel-Ghafar, M.D., Tawee Chotpitayasunondh, M.D., Zhancheng Gao, M.D., Ph.D., Frederick G. Hayden, M.D., Nguyen Duc Hien, M.D., Ph.D., Menno D. de Jong, M.D., Ph.D., Azim Naghdaliyev, M.D., J.S. Malik Peiris, M.D., Nahoko Shindo, M.D., Santoso Soeroso, M.D., and Timothy M. Uyeki, M.D.) assume responsibility for the overall content and integrity of the article. Address reprint requests to Dr. Hayden at the Global Influenza Program, Department of Epidemic and Pandemic Alert and Response, World Health Organization, 20 Ave. Appia, Ch-1211, Geneva 27, Switzerland, or at haydenf@who.int.

Clinical efficacy and safety of a novel tetravalent dengue vaccine in healthy children in Asia: a phase 3, randomised, observer-masked, placebo-controlled trial

BACKGROUND An estimated 100 million people have symptomatic dengue infection every year. This is the first report of a phase 3 vaccine efficacy trial of a candidate dengue vaccine. We aimed to assess the efficacy of the CYD dengue vaccine against symptomatic, virologically confirmed dengue in children. METHODS We did an observer-masked, randomised controlled, multicentre, phase 3 trial in five countries in the Asia-Pacific region. Between June 3, and Dec 1, 2011, healthy children aged 2-14 years were randomly assigned (2:1), by computer-generated permuted blocks of six with an interactive voice or web response system, to receive three injections of a recombinant, live, attenuated, tetravalent dengue vaccine (CYD-TDV), or placebo, at months 0, 6, and 12. Randomisation was stratified by age and site. Participants were followed up until month 25. Trial staff responsible for the preparation and administration of injections were unmasked to group allocation, but were not included in the follow-up of the participants; allocation was concealed from the study sponsor, investigators, and parents and guardians. Our primary objective was to assess protective efficacy against symptomatic, virologically confirmed dengue, irrespective of disease severity or serotype, that took place more than 28 days after the third injection. The primary endpoint was for the lower bound of the 95% CI of vaccine efficacy to be greater than 25%. Analysis was by intention to treat and per procotol. This trial is registered with ClinicalTrials.gov, number NCT01373281. FINDINGS We randomly assigned 10,275 children to receive either vaccine (n=6851) or placebo (n=3424), of whom 6710 (98%) and 3350 (98%), respectively, were included in the primary analysis. 250 cases of virologically confirmed dengue took place more than 28 days after the third injection (117 [47%] in the vaccine group and 133 [53%] in the control group). The primary endpoint was achieved with 56·5% (95% CI 43·8-66·4) efficacy. We recorded 647 serious adverse events (402 [62%] in the vaccine group and 245 [38%] in the control group). 54 (1%) children in the vaccine group and 33 (1%) of those in the control group had serious adverse events that happened within 28 days of vaccination. Serious adverse events were consistent with medical disorders in this age group and were mainly infections and injuries. INTERPRETATION Our findings show that dengue vaccine is efficacious when given as three injections at months 0, 6, and 12 to children aged 2-14 years in endemic areas in Asia, and has a good safety profile. Vaccination could reduce the incidence of symptomatic infection and hospital admission and has the potential to provide an important public health benefit. FUNDING Sanofi Pasteur.

Human Disease from Influenza A (H5N1), Thailand, 2004

Direct contact with sick poultry, young age, pneumonia and lymphopenia, and acute respiratory distress syndrome should prompt specific laboratory testing for H5 influenza.

Correlation of cellular immune responses with protection against culture-confirmed influenza virus in young children.

ABSTRACT The highly sensitive gamma interferon (IFN-γ) enzyme-linked immunosorbent spot (ELISPOT) assay permits the investigation of the role of cell-mediated immunity (CMI) in the protection of young children against influenza. Preliminary studies of young children confirmed that the IFN-γ ELISPOT assay was a more sensitive measure of influenza memory immune responses than serum antibody and that among seronegative children aged 6 to <36 months, an intranasal dose of 107 fluorescent focus units (FFU) of a live attenuated influenza virus vaccine (CAIV-T) elicited substantial CMI responses. A commercial inactivated influenza virus vaccine elicited CMI responses only in children with some previous exposure to related influenza viruses as determined by detectable antibody levels prevaccination. The role of CMI in actual protection against community-acquired, culture-confirmed clinical influenza by CAIV-T was investigated in a large randomized, double-blind, placebo-controlled dose-ranging efficacy trial with 2,172 children aged 6 to <36 months in the Philippines and Thailand. The estimated protection curve indicated that the majority of infants and young children with ≥100 spot-forming cells/106 peripheral blood mononuclear cells were protected against clinical influenza, establishing a possible target level of CMI for future influenza vaccine development. The ELISPOT assay for IFN-γ is a sensitive and reproducible measure of CMI and memory immune responses and contributes to establishing requirements for the future development of vaccines against influenza, especially those used for children.

Micafungin Versus Liposomal Amphotericin B for Pediatric Patients With Invasive Candidiasis: Substudy of a Randomized Double-blind Trial

Background: Invasive candidiasis is increasingly prevalent in premature infants and seriously ill children, and pediatric data on available antifungal therapies are lacking. Methods: We conducted a pediatric substudy as part of a double-blind, randomized, multinational trial to compare micafungin (2 mg/kg) with liposomal amphotericin B (3 mg/kg) as first-line treatment of invasive candidiasis. Treatment success was defined as clinical and mycologic response at the end of therapy. Statistical analyses were descriptive, as the sample size meant that the study was not powered for hypothesis testing. Results: One hundred six patients were included in the intent-to-treat population; and 98 patients—48 patients in the micafungin group and 50 patients in the liposomal amphotericin B group—in the modified intent-to-treat population. Baseline characteristics were balanced between treatment groups. Overall, 57 patients were <2 years old including 19 patients who were premature at birth; and 41 patients were 2 to <16 years old. Most patients (91/98, 92.9%) had candidemia, and 7/98 (7.1%) patients had other forms of invasive candidiasis. Treatment success was observed for 35/48 (72.9%) patients treated with micafungin and 38/50 (76.0%) patients treated with liposomal amphotericin B. The difference in proportions adjusted for neutropenic status was −2.4% [95% CI: (−20.1 to 15.3)]. Efficacy findings were consistent, independent of the neutropenic status, the age of the patient, and whether the patient was premature at birth. Both treatments were well tolerated, but with a lower incidence of adverse events that led to discontinuation in the micafungin group (2/52, 3.8%) compared with the liposomal amphotericin B group (9/54, 16.7%) (P = 0.05, Fisher exact test). Conclusions: Micafungin seems to be similarly effective and as safe as liposomal amphotericin B for the treatment of invasive candidiasis in pediatric patients. (ClinicalTrials.gov number, NCT00106288).

WHO Rapid Advice Guidelines for pharmacological management of sporadic human infection with avian influenza A (H5N1) virus

Summary Recent spread of avian influenza A (H5N1) virus to poultry and wild birds has increased the threat of human infections with H5N1 virus worldwide. Despite international agreement to stockpile antivirals, evidence-based guidelines for their use do not exist. WHO assembled an international multidisciplinary panel to develop rapid advice for the pharmacological management of human H5N1 virus infection in the current pandemic alert period. A transparent methodological guideline process on the basis of the Grading Recommendations, Assessment, Development and Evaluation (GRADE) approach was used to develop evidence-based guidelines. Our development of specific recommendations for treatment and chemoprophylaxis of sporadic H5N1 infection resulted from the benefits, harms, burden, and cost of interventions in several patient and exposure groups. Overall, the quality of the underlying evidence for all recommendations was rated as very low because it was based on small case series of H5N1 patients, on extrapolation from preclinical studies, and high quality studies of seasonal influenza. A strong recommendation to treat H5N1 patients with oseltamivir was made in part because of the severity of the disease. Similarly, strong recommendations were made to use neuraminidase inhibitors as chemoprophylaxis in high-risk exposure populations. Emergence of other novel influenza A viral subtypes with pandemic potential, or changes in the pathogenicity of H5N1 virus strains, will require an update of these guidelines and WHO will be monitoring this closely.

Maternal viral load and timing of mother-to-child HIV transmission Bangkok Thailand.

OBJECTIVES To determine the proportion of HIV-1-infected infants infected in utero and intrapartum, the relationship between transmission risk factors and time of transmission, and the population-attributable fractions for maternal viral load. DESIGN Prospective cohort study of 218 formula-fed infants of HIV-1-infected untreated mothers with known infection outcome and a birth HIV-1-positive DNA PCR test result. METHODS Transmission in utero was presumed to have occurred if the birth sample (within 72 h of birth) was HIV-1-positive by PCR; intrapartum transmission was presumed if the birth sample tested negative and a later sample was HIV-1-positive. Two comparisons were carried out for selected risk factors for mother-to-child transmission: infants infected in utero versus all infants with a HIV-1-negative birth PCR test result, and infants infected intrapartum versus uninfected infants. RESULTS Of 49 infected infants with an HIV-1 birth PCR result, 12 (24.5%) [95% confidence interval (CI), 14 -38] were presumed to have been infected in utero and 37 (75.5%) were presumed to have been infected intrapartum. The estimated absolute overall transmission rate was 22.5%; this comprised 5.5% (95% CI, 3-9) in utero transmission and 18% (95% CI, 13-24) intrapartum transmission. Intrapartum transmission accounted for 75.5% of infections. High maternal HIV-1 viral load (> median) was a strong risk factor for both in utero [adjusted odds ratio (AOR) 5.8 (95% CI, 1.4-38.8] and intrapartum transmission (AOR, 4.4; 95% CI, 1.9-11.2). Low birth-weight was associated with in utero transmission, whereas low maternal natural killer cell and CD4(+) T-lymphocyte percentages were associated with intrapartum transmission. The population-attributable fraction for intrapartum transmission associated with viral load > 10 000 copies/ml was 69%. CONCLUSIONS Our results provide further evidence that most perinatal HIV-1 transmission occurs during labor and delivery, and that risk factors may differ according to time of transmission. Interventions to reduce maternal viral load should be effective in reducing both in utero and intrapartum transmission.

Efficacy and safety of a live attenuated, cold-adapted influenza vaccine, trivalent against culture-confirmed influenza in young children in Asia.

Background: This study was designed to evaluate the efficacy and safety of cold-adapted influenza vaccine, trivalent (CAIV-T) against culture-confirmed influenza in children 12 to <36 months of age during 2 consecutive influenza seasons at multiple sites in Asia. Methods: In year 1, 3174 children 12 to <36 months of age were randomized to receive 2 doses of CAIV-T (n = 1900) or placebo (n = 1274) intranasally ≥28 days apart. In year 2, 2947 subjects were rerandomized to receive 1 dose of CAIV-T or placebo. Results: Mean age at enrollment was 23.5 ± 7.4 months. In year 1, efficacy of CAIV-T compared with placebo was 72.9% [95% confidence interval (CI): 62.8–80.5%] against antigenically similar influenza subtypes, and 70.1% (95% CI: 60.9–77.3%) against any strain. In year 2, revaccination with CAIV-T demonstrated significant efficacy against antigenically similar (84.3%; 95% CI: 70.1–92.4%) and any (64.2%; 95% CI: 44.2–77.3%) influenza strains. In year 1, fever, runny nose/nasal congestion, decreased activity and appetite, and use of fever medication were more frequent with CAIV-T after dose 1. Runny nose/nasal congestion after dose 2 (year 1) and dose 3 (year 2) and use of fever medication after dose 3 (year 2) were the only other events reported significantly more frequently in CAIV-T recipients. Conclusions: CAIV-T was well tolerated and effective in preventing culture-confirmed influenza illness over multiple and complex influenza seasons in young children in Asia.

Antiviral resistance during the 2009 influenza A H1N1 pandemic: public health, laboratory, and clinical perspectives

Influenza A H1N1 2009 virus caused the first pandemic in an era when neuraminidase inhibitor antiviral drugs were available in many countries. The experiences of detecting and responding to resistance during the pandemic provided important lessons for public health, laboratory testing, and clinical management. We propose recommendations for antiviral susceptibility testing, reporting results, and management of patients infected with 2009 pandemic influenza A H1N1. Sustained global monitoring for antiviral resistance among circulating influenza viruses is crucial to inform public health and clinical recommendations for antiviral use, especially since community spread of oseltamivir-resistant A H1N1 2009 virus remains a concern. Further studies are needed to better understand influenza management in specific patient groups, such as severely immunocompromised hosts, including optimisation of antiviral treatment, rapid sample testing, and timely reporting of susceptibility results.