Respiratory viruses and influenza-like illness: Epidemiology and outcomes in children aged 6 months to 10 years in a multi-country population sample.

BACKGROUND: Better population data on respiratory viruses in children in tropical and southern hemisphere countries is needed. METHODS: The epidemiology of respiratory viruses among healthy children (6 months to <10 years) with influenza-like illness (ILI) was determined in a population sample derived from an influenza vaccine trial (NCT01051661) in 17 centers in eight countries (Australia, South East Asia and Latin America). Active surveillance for ILI was conducted for approximately 1 year (between February 2010 and August 2011), with PCR analysis of nasal and throat swabs. RESULTS: 6266 children were included, of whom 2421 experienced 3717 ILI episodes. Rhinovirus/enterovirus had the highest prevalence (41.5%), followed by influenza (15.8%), adenovirus (9.8%), parainfluenza and respiratory syncytial virus (RSV) (both 9.7%), coronavirus (5.6%), human metapneumovirus (5.5%) and human bocavirus (HBov) (2.0%). Corresponding incidence per 100 person-years was 29.78, 11.34, 7.03, 6.96, 6.94, 4.00, 3.98 and 1.41. Except for influenza, respiratory virus prevalence declined with age. The incidence of medically-attended ILI associated with viral infection ranged from 1.03 (HBov) to 23.69 (rhinovirus/enterovirus). The percentage of children missing school or daycare ranged from 21.4% (HBov) to 52.1% (influenza). CONCLUSIONS: Active surveillance of healthy children provided evidence of respiratory illness burden associated with several viruses, with a substantial burden in older children.

Prevalence and Incidence of Respiratory Syncytial Virus and Other Respiratory Viral Infections in Children Aged 6 Months to 10 Years With Influenza-like Illness Enrolled in a Randomized Trial.

BACKGROUND: The high burden of respiratory syncytial virus (RSV)-associated morbidity and mortality makes vaccine development a priority. METHODS: As part of an efficacy trial of pandemic influenza vaccines (NCT01051661), RSV epidemiology in healthy children aged 6 months to <10 years at first vaccination with influenza-like illness (ILI) was evaluated in Australia, Brazil, Colombia, Costa Rica, Mexico, the Philippines, Singapore, and Thailand between February 2010 and August 2011. Active surveillance for ILI was conducted for approximately 1 year, with nasal and throat swabs analyzed by polymerase chain reaction. The prevalence and incidence of RSV among ILI episodes were calculated. RESULTS: A total of 6266 children were included, of whom 2421 experienced 3717 ILI episodes with a respiratory sample available. RSV was detected for 359 ILI episodes, a prevalence of 9.7% (95% confidence interval: 8.7-10.7). The highest prevalence was in children aged 12-23 or 24-35 months in all countries except the Philippines, where it was in children aged 6-11 months. The incidence of RSV-associated ILI was 7.0 (6.3-7.7) per 100 person-years (PY). Eighty-eight ILI episodes resulted in hospitalization, of which 8 were associated with RSV (prevalence 9.1% [4.0-17.1]; incidence 0.2 [0.1-0.3] per 100 PY). The incidence of RSV-associated ILI resulting in medical attendance was 6.0 (5.4-6.7) per 100 PY. RSV B subtypes were observed more frequently than A subtypes. CONCLUSIONS: Active surveillance demonstrated the considerable burden of RSV-associated illness that would not be identified through hospital-based surveillance, with a substantial part of the burden occurring in older infants and children.

Safety and immunogenicity of a rederived, live-attenuated dengue virus vaccine in healthy adults living in Thailand: a randomized trial.

Safety and immunogenicity of two formulations of a live-attenuated tetravalent dengue virus (TDEN) vaccine produced using rederived master seeds from a precursor vaccine were tested against a placebo control in a phase II, randomized, double blind trial (NCT00370682). Two doses were administered 6 months apart to 120 healthy, predominantly flavivirus-primed adults (87.5% and 97.5% in the two vaccine groups and 92.5% in the placebo group). Symptoms and signs reported after vaccination were mild to moderate and transient. There were no vaccine-related serious adverse events or dengue cases reported. Asymptomatic, low-level viremia (dengue virus type 2 [DENV-2], DENV-3, or DENV-4) was detected in 5 of 80 vaccine recipients. One placebo recipient developed a subclinical natural DENV-1 infection. All flavivirus-unprimed subjects and at least 97.1% of flavivirus-primed subjects were seropositive to antibodies against all four DENV types 1 and 3 months post-TDEN dose 2. The TDEN vaccine was immunogenic with an acceptable safety profile in flavivirus-primed adults.

Relative efficacy of AS03-adjuvanted pandemic influenza A(H1N1) vaccine in children: results of a controlled, randomized efficacy trial.

BACKGROUND: The vaccine efficacy (VE) of 1 or 2 doses of AS03-adjuvanted influenza A(H1N1) vaccine relative to that of 2 doses of nonadjuvanted influenza A(H1N1) vaccine in children 6 months to <10 years of age in a multinational study conducted during 2010-2011. METHODS: A total of 6145 children were randomly assigned at a ratio of 1:1:1 to receive 2 injections 21 days apart of A/California/7/2009(H1N1)-AS03 vaccine at dose 1 and saline placebo at dose 2, 2 doses 21 days apart of A/California/7/2009(H1N1)-AS03 vaccine (the Ad2 group), or 2 doses 21 days apart of nonadjuvanted A/California/7/2009(H1N1) vaccine (the NAd2 group). Active surveillance for influenza-like illnesses continued from days 14 to 385. Nose and throat samples obtained during influenza-like illnesses were tested for A/California/7/2009(H1N1), using reverse-transcriptase polymerase chain reaction. Immunogenicity, reactogenicity, and safety were assessed. RESULTS: There were 23 cases of confirmed 2009 pandemic influenza A(H1N1) (A[H1N1]pdm09) infection for the primary relative VE analysis. The VE in the Ad2 group relative to that in the NAd2 group was 76.8% (95% confidence interval, 18.5%-93.4%). The benefit of the AS03 adjuvant was demonstrated in terms of the greater immunogenicity observed in the Ad2 group, compared with the NAd2 group. CONCLUSION: The 4-8-fold antigen-sparing adjuvanted pandemic influenza vaccine demonstrated superior and clinically important prevention of A(H1N1)pdm09 infection, compared with nonadjuvanted vaccine, with no observed increase in medically attended or serious adverse events. These data support the use of adjuvanted influenza vaccines during influenza pandemics. Clinical Trials Registration. NCT01051661.

Extended antigen sparing potential of AS03-adjuvanted pandemic H1N1 vaccines in children, and immunological equivalence of two formulations of AS03-adjuvanted H1N1 vaccines: results from two randomised trials.

BACKGROUND: Pandemic influenza vaccine manufacturing capacity and distribution agility is enhanced through the availability of equivalent antigen-sparing vaccines. We evaluated equivalence in terms of immunogenicity between GlaxoSmithKline Vaccines' A/California/7/2009 (H1N1)v-like-AS03 vaccines manufactured in Dresden (D-Pan), and Quebec (Q-Pan). METHODS: In two studies, 334 adults 18-60 years of age received 2 doses of D-Pan or Q-Pan containing 3.75 µg haemagglutinin antigen (HA) adjuvanted with AS03A administered 21 days apart, and 209 children 3-9 years of age received 1 reduced dose of D-Panor Q-Pan (0.9 µg HA) or Q-Pan (1.9 µg HA) with AS03B. Haemagglutination inhibition (HI) titres were assessed before and 21 days post-vaccination. HI persistence was assessed after 12 months in adults and 6 months in children. RESULTS: Pre-defined criteria for immunological equivalence of Q-Pan versus D-Pan were achieved in both populations. After one vaccine dose, ≥97.6% of adults and children had HI titres ≥1:40, with increases in titre ≥25.7-fold. CHMP and CBER regulatory acceptance criteria for influenza vaccines were exceeded by all groups in both studies at Day 21. In adults,the percentage with HI titres ≥1:40 at Month 12 was 82.9% (Q-Pan) and 84.0% (D-Pan). In children, the percentages at Month 6 were 75.3.3% (Q-Pan0.9), 85.1% (D-Pan0.9) and 79.3% (Q-Pan1.9). Safety profile of the study vaccines was consistent with previously published data. CONCLUSION: Two studies indicate that A/California/7/2009 (H1N1)v-like HA manufactured at two sites and combined with AS03 are equivalent in terms of immunogenicity in adults and children and highly immunogenic. Different HA doses elicited an adequate immune response through 180 days post-vaccination in children 3-9 years of age. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00979407 and NCT01161160.

A randomized controlled study to evaluate the immunogenicity of a trivalent inactivated seasonal influenza vaccine at two dosages in children 6 to 35 months of age.

The trivalent inactivated influenza vaccine Fluarix™ is licensed in the US for adults and children from 3 years old. This randomized observer-blind study (NCT00764790) evaluated Fluarix™ at two doses; 0.25 ml (Flu-25) and 0.5 ml (Flu-50) in children aged 6-35 months. The primary objective was to demonstrate immunogenic non-inferiority vs. a control vaccine (Fluzone®; 0.25 ml). Children received Flu-25 (n = 1107), Flu-50 (n = 1106) or control vaccine (n = 1104) at Day 0 and for un-primed children, also on Day 28. Serum hemagglutination-inhibition titers were determined pre-vaccination and at Day 28 (primed) or Day 56 (un-primed). Non-inferiority was assessed by post-vaccination geometric mean titer (GMT) ratio, (upper 95% confidence interval [CI] ≤ 1.5) and difference in seroconversion rate (upper 95% CI ≤ 10%). Reactogenicity/safety was monitored. The immune response to Flu-50 met all regulatory criteria. Indicated by adjusted GMT ratios [with 95% CI], the criteria for non-inferiority of Flu-50 vs. control vaccine were reached for the B/Florida strain (1.13 [1.01-1.25]) but not for the A/Brisbane/H1N1 (1.74 [1.54-1.98]) or A/Uruguay/H3N2 (1.72 [1.57-1.89]) strains. In children aged 18-35 months similar immune responses were observed for Flu-50 and the control vaccine. Flu-50 induced a higher response than Flu-25 for all strains. Temperature (≥ 37.5°C) was reported in 6.2%, 6.4%, and 6.6% of the Flu-25, Flu-50, and control group, respectively. Reactogenicity/safety endpoints were within the same range for all vaccines. In children aged 6-35 months, immune responses with Flu-50 fulfilled regulatory criteria but did not meet the pre-defined criteria for non-inferiority vs. control. This appeared to be due to differences in immunogenicity in children aged<18 months.

Safety and immunogenicity of a tetravalent live-attenuated dengue vaccine in flavivirus-naive infants.

A Phase I/II observer-blind, randomized, controlled trial evaluated the safety and immunogenicity of a dengue virus (DENV) vaccine candidate in healthy Thai infants (aged 12-15 months) without measurable pre-vaccination neutralizing antibodies to DENV and Japanese encephalitis virus. Fifty-one subjects received two doses of either DENV (N = 34; four received 1/10th dose) or control vaccine (N = 17; dose 1, live varicella; dose 2, Haemophilus influenzae type b). After each vaccine dose, adverse events (AEs) were solicited for 21 days, and non-serious AEs were solicited for 30 days; serious AEs (SAEs) were recorded throughout the study. Laboratory safety assessments were performed at 10 and 30 days; neutralizing antibodies were measured at 30 days. The DENV vaccine was well-tolerated without any related SAEs. After the second dose, 85.7% of full-dose DENV vaccinees developed at least trivalent and 53.6% developed tetravalent neutralizing antibodies ≥ 1:10 to DENV (control group = 0%). This vaccine candidate, therefore, warrants continued development in this age group (NCT00322049; clinicaltrials.gov).

Immunogenicity of a human rotavirus vaccine (RIX4414) after storage at 37 °C for seven days.

AIM: The lyophilized formulation of the human rotavirus vaccine, RIX4414 (RotarixTM), is recommended to be stored at 2°C-8°C for optimal immunogenicity. In some settings with inadequate infrastructure for vaccine storage, unforeseen circumstances may cause cold chain breakage, resulting in the vaccine to be left at ambient temperatures. This study evaluated the heat stability of lyophilized RIX4414 vaccine in terms of immunogenicity when stored at tropical room temperature (37 °C) for 7 days before reconstitution. RESULTS: There was no statistically significant difference detected between RIX4414 vaccine stored at 2 °C-8 °C (Group RIX4414_control, n = 171) and that stored at 37 °C for 7 days (Group RIX4414_37 °C, n = 47) in terms of seroconversion rate and vaccine take. The anti-rotavirus IgA seroconversion rate 2 months post-Dose 2 was 84.7% (95% CI: 78.1%-90%) and 87.8% (95% CI: 73.8%-95.9%) in Groups RIX4414_control and RIX4414_37 °C, respectively. None of the 25 infants in placebo group seroconverted. The vaccine take in the respective vaccine groups were 88% (95% CI: 82.1%-92.5%) and 93.5% (95% CI: 82.1%-98.6%) and Geometric Mean Concentrations (GMCs) were 134.4 U/mL (95% CI: 104.5-172.9) and 163.7 U/mL (95% CI: 98.9-271.1). METHODS: Healthy infants aged 6-12 weeks, received two oral doses of either the RIX4414 vaccine stored at 2 °C-8 °C, RIX4414 vaccine stored at 37 °C for 7 days or placebo, according to a 0, 2 month schedule. Seroconversion rates in terms of anti-rotavirus IgA antibody levels (cut off: ≥ 20 U/mL by ELISA), anti-rotavirus IgA antibody GMCs and vaccine take were calculated 2 months post-Dose 2. CONCLUSION: Lyophilized RIX4414 vaccine stored at 37°C for 7 days before reconstitution has similar immunogenicity as the vaccine stored at 2 °C-8 °C. These results supported the use of RIX4414 in settings where the vaccine might be exposed to higher than the recommended storage temperatures.

Immunogenicity of a live-attenuated human rotavirus RIX4414 vaccine with or without buffering agent.

AIM: The lyophilized form of the human rotavirus RIX4414 vaccine (Rotarix()) is usually reconstituted with a liquid calcium carbonate (CaCO(3)) buffer and administered orally. However, errors in the reconstitution could occur (e.g. reconstituted with water instead of CaCO(3) buffer) or the buffer might be temporarily unavailable in few instances. This study was conducted to evaluate the immunogenicity of the RIX4414 vaccine if the vaccine was reconstituted with other agents (e.g., water) instead of CaCO(3) buffer. RESULTS: There was no statistical difference detected between RIX4414 vaccine reconstituted with buffer or water in vaccine take or in seroconversion rate. The anti-rotavirus Immunoglobulin A (IgA) seroconversion rate 2 months post-Dose 2 was 84.7% (95% CI: 78.1-90.0) for the group with buffer and 78.6% (95% CI: 71.2-84.8) for the group with water. Solicited and unsolicited symptoms reported were similar across groups. No vaccine related serious adverse events (SAEs) were reported. METHODS: Healthy infants aged 6-12 weeks, received two oral doses of the RIX4414 vaccine/placebo, reconstituted either with injectable water or CaCO(3) buffer according to a 0, 2 month schedule. Seroconversion rates in terms of anti-RV IgA antibody levels (cut off: >/=20 U/ml by ELISA) and vaccine take were calculated 2 months post-Dose 2. Solicited and unsolicited symptoms reported during the 15- and 31-day follow-up period after each dose and SAE s reported during the entire study period were recorded. CONCLUSION: Administration of RIX4414 vaccine in the absence of CaCO(3) buffer was shown to be well tolerated and immunogenic in Thai infants.

Invasive pneumococcal disease in Phramongkutklao Hospital 2004-2008: clinical data, serotype distribution and antimicrobial resistance patterns.

OBJECTIVE: To describe the clinical course, serotype distribution and antimicrobial resistance patterns of invasive pneumococcal disease (IPD) cases in a public hospital. MATERIAL AND METHOD: Retrospective review of IPD cases occurring from January 2004 through December 2008 was performed. Antibiotic susceptibility testing and serotyping were performed for available isolates. RESULTS: Fifty one IPD cases occurred during the study period, of which 47 had medical records available for review. The majority of cases occurred among children under 5 years of age (23.4%) and adults over 60 years of age (36.1%). Underlying diseases were identified in 72.3% of patients. Fifty-three percent of cases were associated with pneumonia, while 17% had meningitis, and 15% had isolated bacteremia. Serotype could be determined for 15 (31.9%) isolates, and 6B was most common. Based on current antibiotic susceptibility breakpoints for meningitis, 4 of the 7 available isolates from meningitis cases were penicillin resistant and one had reduced susceptibility to cefotaxime. Among non-meningitis isolates, 96.7% were penicillin susceptible and 3.3% had intermediate susceptibility to penicillin. Overall case fatality proportion was 19%. CONCLUSION: At this tertiary care hospital in Bangkok, IPD has disproportionately affected young children and the elderly. High rates of penicillin resistance among meningitis cases, the most severe form of IPD, underscore the need of appropriate treatment strategies and vaccine usage.

Primary vaccination with a new heptavalent DTPw-HBV/Hib-Neisseria meningitidis serogroups A and C combined vaccine is well tolerated.

OBJECTIVE: Safety and reactogenicity of a new heptavalent DTPw-HBV/Hib-MenAC (diphtheria, tetanus, whole cell pertussis-hepatitis B virus/Haemophilus influenzae type b-Neisseria meningitidis serogroups A and C) vaccine was compared with a widely used pentavalent DTPw-HBV/Hib vaccine. METHODS: Three phase III randomized studies comparable in design and methodology, in which healthy infants received DTPw-HBV/Hib-MenAC (N=1334) or DTPw-HBV/Hib (N=446) at 2, 4, and 6 months, were pooled for analysis. Solicited symptoms were recorded for 4 days, and unsolicited adverse events for 31 days after each dose. Serious adverse events (SAEs) were recorded throughout the studies. RESULTS: There were no significant differences between the two groups in the proportion of subjects with fever >39.5 degrees C or >40.0 degrees C (p<0.005). Compared to group DTPw-HBV/Hib, a significantly higher percentage of subjects in group DTPw-HBV/Hib-MenAC reported fever >39 degrees C (21.2% vs. 14.8%, p=0.004). Fever subsided quickly, did not lead to differences in attendance to medical services and did not increase from dose to dose. Sixty-seven SAEs were reported, 56/1334 (4.2%) in group DTPw-HBV/Hib-MenAC and 11/446 (2.5%) in the DTPw-HBV/Hib group. CONCLUSION: Overall, the heptavalent and pentavalent vaccines had similar safety profiles. The difference observed in percentage of subjects with fever >39 degrees C did not lead to differences in medically attended visits for fever.

The immunological response of Thai infants to haemophilus influenzae type B polysaccharide-tetanus conjugate vaccine co-administered in the same syringe with locally produced diphtheria-tetanus-pertussis vaccine.

OBJECTIVE: Comparing the immunogenicity and reactogenicity of three vaccine combinations. These were GlaxoSmithKline Biologicals' (GSK) Haemophilus influenzae type b vaccine (Hib-TT, Hiberix) administered with the local Government Pharmaceutical Organization's (GPO) diphtheria-tetanus-pertussis whole cell (DTPw) vaccine, Hib-TT mixed with GPO's DTPw vaccine, or Hib-IT mixed with GSKs' DTPw vaccine (Tritanrix). MATERIAL AND METHOD: An open, randomized, controlled, single center study of three hundred and sixty infants. They were randomized into three groups to receive either Hib-TT Hiberix mix with GPOs' DTPw vaccine (group 1), Hib-TT mixed with GPO's DTPw vaccine (group 2), or Hib-TT mixed with GSKs' DTPw vaccine (Tritanrix; group 3) at two, four and six months of age. RESULT: One month after the third dose, all subjects had antibodies level against Hib polyribosylribitol phosphate (PRP) > or = 0.15 microg/ml. All 11 subjects except two (in group 2) had anti-PRP levels > or = 1.0 microg/ml. The geometric mean concentrations were similar in all three groups. Over 96% of the subjects in all three groups demonstrated an immunological response to diphtheria, tetanus, and pertussis antigens. There was no diference among the three groups in terms of severe local reaction and fever. CONCLUSION: The present study showed that the combined vaccines produced an effective antibody response with no increase in reactogenicity compared to separately administrated vaccines.

Seroprevalence of hepatitis A in thai army medical cadets and nursing students: a reflection of regional risk differences.

A cross-sectional study of 432 army college students comprising 278 medical cadets and 154 nursing students, ages ranging from 15 to 26 years, was conducted in 2001 to determine the seroprevalence of hepatitis A virus (HAV) antibody. Serum specimens were tested for HAV antibody by a commercial enzyme immunoassay method. Anti-HAV was detected in 14.0%, 17.5%, and 15.3% of medical cadets, nursing students, and the total cohort, respectively. There was no statistically significant difference in seroprevalence between medical cadets and nursing students. Increasing prevalence of HAV correlated with increasing age. Significantly higher seroprevalence was detected in students from provinces outside of Bangkok compared to those who were from Bangkok (18.7% vs. 9.8%). The highest HAV seroprevalence was observed in subjects from the northeastern region of Thailand, suggesting that this region may be associated with greater risk for infection and should be the focus of preventive health strategies.

The study transplacental chikungunya virus antibody kinetics, Thailand.

Antibodies to chikungunya virus were detected by hemagglutination-inhibition assay in 33.6% of 2,000 infants' cord sera at delivery. Follow-up of 24 seropositive infants showed that the half-life of antibody persistence was 35.5 days. Chikungunya virus infection is common in Thailand, and routine use of diagnostic assays is needed.

Quantification of HIV-1 RNA load by one-tube-one-step RT PCR and real time PCR assay with TaqMan probe.

OBJECTIVES: To develop a less expensive assay to calculate HIV-1 viral load for use in resource-limited countries. MATERIAL AND METHOD: An In-house One-tube-one-step Viral Load Assay (IOVA) was developed by using real-time PCR-based with TaqMan probe. Primers and probe were designed from the conserved region of sequences from all HIV subtypes. A standard curve was generated from reference virus in various dilutions. IOVA was applied on 105 HIV-positive and 25 HIV-negative samples and compared with the results from ROCHE AMPLICLOR. RESULTS: IOVA measured HIV RNA in the samples ranging from 125 to 2 x 10(6) copies/mL. The coefficient of variation of intra- and inter-assay ranged from 0.68% to 7.89%. The sensitivity, specificity, positive and negative predictive values were 92%, 100%, 100% and 79.5% respectively. The parallel quantitative analysis showed high correlation (r=0.95) between IOVA and AMPLICOR. CONCLUSION: A new HIV-1 viral load assay was developed and validated. It was reliable and less expensive.

Transplacentally transferred maternal-infant antibodies to dengue virus.

Antibodies of all four dengue virus serotypes were detected by hemagglutination inhibition (HI) in 97% of 2,000 infants' cord sera at the time of delivery. In comparison with 250 mother-infant's paired sera, we found that 53% of the infants' serum HI titers were higher than those of the mother's. The mother/infant IgG subclasses 1, 2, 3, and 4 titers were 53.1/87.0, 8.4/11.7, 0.14/0.11, and 1.1/1.0 mg/dL, respectively. In 18 months of follow-up of 100 infants studied, we observed that antibody to dengue virus disappeared in 3% by two months of age, in 19% by four months of age, in 72% by six months of age, in 99% by nine months of age, and in 100% by 12 months of age, with a half-life of 41 days. We conclude that the antibodies to dengue virus disappeared in the first year of life. We suggest that the most appropriate age for vaccination with a live-attenuated dengue vaccine in an endemic area is one year of age.