Long-term Follow-up of Mahidol-Aventis Tetravalent Live Attenuated Dengue Vaccine in Adults and Children 1998-2007
1. After DEN vaccine administration
- Safety and immunogenicity of Mahidol-Aventis tetravalent DEN vaccine in adults (n=59) and schools chidren (n=103) were established.
- Single dose of DEN vaccine induced tetravalent seroconversion in semi-immune subjects.
2. Long-term safety: Flavivirus Naïve Adults & Children Vaccine Recipients
- Mild dengue fever (DF) 7 cases were observed (2 adults, 5 children) 7 years after vaccination.
- No severe form of dengue disease occured in recipients exposed to wild type DEN infections, 7-8 years after vaccine administration.
Results suggest that preexisting dengue antibodies induced by the vaccine do not enhance dengue illness (no ADE), and use of the vaccine in dengue endemic area is safe.
3. Long-term NAb: Flavivirus Naïve Children Recipients of Vaccine
- Antibodies to DEN viruses of vaccine recipients were well persisting.
- GMT of NAb for DEN-1 and DEN-2 of vaccine recipients with wild-type (Wt) DEN infections were significantly higher than those of recipients without Wt DEN infection and surpassed that for DEN-3.
Immune Response and Occurrence of Dengue Infection in Thai Children 3-8 Years after Mahidol Live Attenuated Tetravalent Dengue Vaccine (LATDV)
In 1992-1997, 140 Thai children 4-15 years of age received LATDV. 113 were participated in this retrospective cohort study in 2001. The vaccinated subjects with NAb increased compared with 3–8 years earlier was probably due to subsequent Wt DEN infections. There were no excess hospitalizations for clinically suspected DF or DHF in vaccinees (1 DF and 3 DHF) compared with controls (14 DHF). Results suggest that preexisting dengue antibodies induced by LATDV do not enhance dengue illness (no ADE), and the use of the vaccine in a dengue-endemic area is safe.
Epidemiological Study of Dengue Infection in Children Ratcahburi Provience, Thailand 2006-09
A prospective study of dengue virus infection in primary school children in Muang district, Ratchaburi Province, Thailand is a descriptive dynamic cohort school-based study initiated in January 2005 and fully established in February 2006.
To determine the epidemiology of symptomatic dengue infection. To develop a study model in which to study the efficay of a dengue vaccine.
1. Active Case Surveillance Jan–Dec 2006: A total of 8,429 student-absent episodes occurred; 1,892 had fever, 734 visited Ratchaburi Hospital (RH) and 580 were hospitalized.
Annual number of children with fever (1,892/2,625) was 0.7 day/child-year.
2. Symptomatic dengue infection: 51 cases (aged 5-11 y) were laboratory postive for acute dengue infection, accounting for 2.7 % of all 1892 febrile cases. 1o and 2o dengue infections were 4 cases and 47 cases, respectively. The disease occured all year and highest in August 10 cases. The incidence of symptomatic dengue virus infection (51/3,024) was 1.7%.
Dengue Virus Infections in the First 2 Years of Life and the Kinetics of Transplacentally Transferred DEN NAb in Thai Children
During Nov 2000 to Mar 2001, serum samples from 219 mother-child pairs and 140 children were studied. Antiboies were found in 97% of cord serum samples and disappeared in 27%, 80%, and 95% of the children by the age of 6, 9, and 12 m, respectively. GMTs to 4 dengue serotypes decreased to 5.4-15.5 in 6-month-old infants. 11/12 children acquired dengue infection at 6 m of age and beyond; 1 had the infection at 3 m of age. 2 exhibited undifferentiated febrile illnesses, and 10 had subclinical infections. Evidence of dengue virus infection and very low GMTs against
all dengue serotypes in children at 6 m of age and beyond was demonstrated. There was no evidence that maternal antibodies were harmful to infants exposed to Wt DEN infections. Dengue virus infection rates increase from 12 m of age onward. These data provide information for supporting the optimal age at vaccination.
Chimerix Dengue Vaccine Trial in Thai Children This is the first phase IIb dengue trial in Thai Children 4-11 years of age in Ratchaburi Province, Thailand. If this vaccine is shown to be effective prevention for dengue disease will be soon available.