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 AS03_A 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 AS03_B. 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).

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.

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.

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.

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.

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.

Perinatal dengue infection

We report a case of vertical transmission of dengue infection in an infant. The mother's was a term pregnancy with a history of chronic hypertension. She presented with high fever of 3 days duration 5 days prior to delivery. Her initial complete blood count showed platelet count of 64,000/mm3. Dengue hemorrhagic fever was diagnosed 2 days later and symptomatic treatment was given. During labor her platelets dropped to 11,000/mm3 and platelet concentrate was given. Cesarean section was performed due to prolonged second stage of labor. Her infant was normal at birth except for petechiae on the left thigh. The child's platelet count was 34,000/mm3 and low grade fever was detected on the first day. Clinical sepsis was suspected and antibiotic treatment was started and continued for 4 days until all the cultures came back as negative. Both mother and her baby made an uneventful recovery and were discharged 6 days after delivery with normal platelet counts. Maternal blood was positive for IgM antibody to dengue virus. Both cord blood and the baby's blood were positive for dengue virus serotype 2 by PCR.

Epidemiology of invasive meningococcal disease in 13 government hospitals in Thailand, 1994-1999

This study was conducted to elucidate the magnitude of problem and the clinical course of invasive meningococcal infection from 13 government hospitals in Thailand between 1994 and 1999. Thirty-six strains of Neisseria meningitidis were isolated from 16 blood and 24 cerebrospinal fluid specimens; 4 patients had positive culture in both blood and CSF. Of the 16 strains, 9 (56.3%) were serogroup B. Seventy-one and eighty-four percent of the isolates were susceptible to penicillin and cefotaxime/ceftriaxone respectively. Five out of six penicillin-nonsusceptible strains were found to be relatively resistant to penicillin with the MIC of 0.125 microg/ml. Of 33 patients whose medical records were available, 21 were males and 12 were females, with a mean age of 11.2 years. Fifteen patients (45.5%) presented with meningococcemia and 18 patients (54.5%) presented with meningococcal meningitis. Hypotension and purpura were found in 24.2% and 33.3% of patients respectively. The overall mortality rate was 9.1%. In conclusion, meningococcal disease is not common in Thailand, meningococcemia is a life-threatening condition whereas meningococcal meningitis is much less severe. The prevalence of meningococci relatively resistant to penicillin seems to be increasing.