Safety and immunogenicity of two formulations of rotavirus vaccine in Vietnamese infants.

BACKGROUND AND AIMS: ROTAVIN-M1® (licensed, frozen vaccine) and ROTAVIN (second-generation, liquid candidate vaccine) are two rotavirus vaccine formulations developed from a live attenuated G1P8 (KH0118) strain by Center for Research and Production of Vaccines and Biologicals (POLYVAC), Vietnam. This study compared the safety and immunogenicity of these two formulations. METHODS: A Phase 3, randomized, partially double-blinded, active-controlled study was conducted in healthy infants aged 60-91 days in Vietnam. Infants received two doses of ROTAVIN or ROTAVIN-M1 in a ratio of 2:1 with an interval of 8 weeks. Solicited reactions were collected for 7 days after each vaccination. Blood samples were collected pre-vaccination and 4 weeks after the second vaccination in a subset of infants. Non-inferiority criteria required that the lower bound of 95% confidence intervals (CIs) of the post-vaccination anti-rotavirus IgA GMC (Geometric Mean Concentration) ratio of ROTAVIN/ROTAVIN-M1 should be >0.5. A co-primary objective was to compare the safety of the two vaccines in terms of solicited reactions. RESULTS: A total of 825 infants were enrolled. The post-vaccination GMC was 48.25 (95% CI: 40.59, 57.37) in the ROTAVIN group and 35.04 (95% CI: 27.34, 44.91) in the ROTAVIN-M1 group with an IgA GMC ratio of 1.38 (95% CI: 1.02, 1.86) thus meeting the pre-set criteria for non-inferiority. A total of 605 solicited reactions were reported in 297 (36.0%) participants with 35.4% in the ROTAVIN group and 37.2% in the ROTAVIN-M1 group. There were no cases of intussusception or death reported in the study. CONCLUSIONS: Based on the data generated, it can be concluded that ROTAVIN is immunologically non-inferior and has similar safety profile to ROTAVIN-M1 when administered to infants in a two-dose schedule. Therefore, it can be considered as a more suitable option for programmatic use to prevent rotavirus diarrhoea in Vietnam and the Mekong region. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov identifier: NCT03703336, October 11, 2018.

Single-composition Al3+-singly doped ZnO phosphors for UV-pumped warm white light-emitting diode applications.

The development of full-visible-spectrum phosphors is essential for next-generation light-emitting devices with better light quality. Herein, we report on a novel broad-band-emitting phosphor based on single-composition Al-doped ZnO phosphors. Under the UV excitation of 325 nm, the ZnO : Al phosphor exhibits a full spectrum emission in the visible wavelength range from 400 to 800 nm with a CIE chromaticity coordinate of (0.42, 0.48), a quantum efficiency of 43%, a color rendering index (CRI) of 74, a correlated color temperature (CCT) value of 3873 K and an activation energy of 0.22 eV. A prototype of a UV-pumped warm WLED with a high CRI of 87 and a CCT of 4067 K has been achieved by using only this broad-band-emitting Al3+-doped ZnO phosphor. The obtained results indicate that the single-composition Al3+-singly doped warm white emitting phosphor is a promising candidate for UV-pump warm white light-emitting diodes.

Determination of cut-off cycle threshold values in routine RT-PCR assays to assist differential diagnosis of norovirus in children hospitalized for acute gastroenteritis.

Norovirus (NV) is an important cause of acute gastroenteritis in children, but is also frequently detected in asymptomatic children, which complicates the interpretation of NV detection results in both the clinical setting and population prevalence studies. A total of 807 faecal samples from children aged <5 years hospitalized for acute gastroenteritis were collected in Thai Binh, Vietnam, from January 2011 to September 2012. Real-time RT-PCR was used to detect and quantify NV-RNA in clinical samples. A bimodal distribution of cycle threshold (Ct) values was observed in which the lower peak was assumed to represent cases for which NV was the causal agent of diarrhoea, whereas the higher peak was assumed to represent cases involving an alternative pathogen other than NV. Under these assumptions, we applied finite-mixture modelling to estimate a threshold of Ct <21·36 (95% confidence interval 20·29-22·46) to distinguish NV-positive patients for which NV was the likely cause of diarrhoea. We evaluated the validity of the threshold through comparisons with NV antigen ELISA results, and comparisons of Ct values in patients co-infected with rotavirus. We conclude that the use of an appropriate cut-off value in the interpretation of NV real-time RT-PCR results may improve differential diagnosis of enteric infections, and could contribute to improved estimates of the burden of NV disease.

Immunogenicity, reactogenicity and safety of the human rotavirus vaccine RIX4414 (Rotarix™) oral suspension (liquid formulation) when co-administered with expanded program on immunization (EPI) vaccines in Vietnam and the Philippines in 2006-2007.

Evaluation of immunogenicity and safety of a 2-dose liquid formulation of human rotavirus vaccine, RIX4414 following WHO's Expanded Program on Immunization (EPI) schedule (0, 1, and 2 months; Month 0 indicates day of enrollment) in Vietnam and the Philippines. Infants aged 6-10 (mean=8.7 ± 1.07 weeks Vietnam) and 5-10 weeks (mean=6.6 ± 1.03 weeks Philippines) received two doses of RIX4414 vaccine (V) and one dose of placebo (PL) or three placebo doses concomitantly with commercially available diphtheria-tetanus-whole-cell pertussis, hepatitis B and oral poliovirus vaccines. The vaccination schedules were: V-V-PL, V-PL-V and PL-PL-PL (Vietnam); PL-V-V, V-PL-V and PL-PL-PL (Philippines). Anti-rotavirus seroconversion rate was assessed pre-vaccination and post-vaccination (ELISA cut-off=20 U/ml). 375 infants were enrolled in each country. Seroconversion rates at one month post-Dose 2 of RIX4414 were Vietnam 63.3% (95% CI: 54.3-71.6) in V-V-PL group and 81.5% (95% CI: 73.4-88) in V-PL-V group; Philippines 70% (95% CI: 61-78) in PL-V-V group and 59.2% (95% CI: 49.8-68) in V-PL-V group. Frequencies of solicited (8-day post-each dose) and unsolicited symptoms (31-day post-each dose) were similar. Two-doses of rotavirus vaccine administered within the WHO EPI offer flexibility in existing schedule, though both schedules provides good immune responses.

Association of environmental tobacco smoking exposure with an increased risk of hospital admissions for pneumonia in children under 5 years of age in Vietnam.

BACKGROUND: The association between environmental tobacco smoking (ETS) and childhood pneumonia has not been established in developed or developing countries. A study was conducted to assess the effect and impact of ETS exposure on pneumonia among children in central Vietnam. METHODS: A population-based large-scale cross-sectional survey was conducted covering all residents of 33 communes in Khanh Hoa Province, the central part of Vietnam. Information on demographics, socioeconomic status and house environment, including smoking status of each household member, was collected from householders. Hospital admissions for pneumonia among children aged <5 years in each household in the previous 12 months were recorded based on caregiver's report. RESULTS: A total of 353 525 individuals living in 75 828 households were identified in the study areas. Of these, 24 781 (7.0%) were aged <5 years. The prevalence of ETS was 70.5% and the period prevalence of hospital admissions for pneumonia was 2.6%. Multiple logistic regression analysis showed that exposure to ETS was independently associated with hospital admissions for pneumonia (adjusted odds ratio 1.55, 95% CI 1.25 to 1.92). The prevalence of tobacco smoking was higher among men than women (51.5% vs 1.5%). It is estimated that 28.7% of childhood pneumonia in this community is attributable to ETS. CONCLUSIONS: Children in Vietnam are exposed to substantial levels of ETS which results in 44 000 excess hospital admissions due to pneumonia each year among children aged <5 years.

Incidence of bacterial meningitis in Asia using enhanced CSF testing: polymerase chain reaction, latex agglutination and culture.

To enhance the detection of bacterial meningitis in an East Asian surveillance study, we employed cerebrospinal fluid (CSF) bacterial culture, latex agglutination (LA) and polymerase chain reaction-enzyme immunoassay (PCR-EIA) testing for Haemophilus influenzae type b (Hib) and Streptococcus pneumoniae (Sp). The sensitivity and specificity of CSF PCR-EIA testing was compared to LA and culture. A meningitis case was defined by one positive result for any of the three tests. The sensitivity of H. influenzae CSF PCR-EIA, LA, and culture was 100%, 40% and 57.5% respectively; and for Sp CSF PCR-EIA, LA and culture, the sensitivity was 100%, 58.3% and 66.7%, respectively. Hib and Sp specificity was 100% by each method. CSF PCR-EIA was more sensitive than culture or LA for the detection of Hib and Sp meningitis cases increasing their incidence by 74% and 50% compared to culture respectively. CSF PCR-EIA should be included for the detection of bacterial meningitis in surveillance studies.

Mycobacterium tuberculosis Beijing genotype emerging in Vietnam.

To assess whether the Mycobacterium tuberculosis Beijing genotype is emerging in Vietnam, we analyzed 563 isolates from new cases by spoligotyping and examined the association between the genotype and age, resistance, and BCG vaccination status. Three hundred one (54%) patients were infected with Beijing genotype strains. The genotype was associated with younger age (and hence with active transmission) and with isoniazid and streptomycin resistance, but not with BCG vaccination.

Changes in cellular response to mycobacterial antigens and cytokine production patterns in leprosy patients during multiple drug therapy.

Changes in Mycobacterium leprae-induced lymphoproliferative responses and mediator release by leprosy patients' lymphocytes were followed during multiple drug therapy (MDT). At the time of diagnosis, multibacillary (MB) patients who did not develop reactions responded to both sonicated M. leprae and synthetic disaccharide coupled to bovine serum albumin (ND-BSA) antigens, but those who would later develop reactions did not respond, even in the presence of added cytokines. The paucibacillary (PB) group initially had high responses to sonicated M. leprae but no response to ND-BSA, even in the presence of added cytokines. In the first year of treatment, the supernatants of PB patients' cell cultures contained factors that enhanced the phytohaemagglutinin (PHA) response of normal cells. In contrast, those MB patients who did not develop reactions at a later stage produced culture supernatants that were inhibitory. Interestingly, the MB patients who later developed reactions during treatment, and did not initially respond to M. leprae, produced supernatants containing enhancing factors, like those of the PB group. Later on in the treatment, all patients had the same patterns: when response to M. leprae decreased from its highest level, inhibitory factors were produced. Further studies revealed that the supernatants which inhibited the PHA response of normal cells contained the active form of transforming growth factor-beta 1, (TGF-beta 1), whatever the disease type or treatment status of the donor. These TGF-beta 1 levels correlated directly with the degree of inhibition. Similarly supernatants that neither inhibited nor enhanced PHA responses contained the highest levels of interleukin-10 (IL-10), while those from treated patients that enhanced contained the lowest levels of interleukin-4 (IL-4) and interferon-gamma (IFN-gamma). These cytokine correlations transcended the conventional disease classification, and imply that all patients pass through a sequence of patterns of immune response during treatment. These treatment-induced changes may explain occasional reports of response patterns at variance with the 'immunological spectrum' of leprosy.