Rotavirus vaccine effectiveness in Hong Kong children.

BACKGROUND: Rotavirus is a common infectious cause of childhood hospitalisation in Hong Kong. Rotavirus vaccines have been used in the private sector since licensure in 2006 but have not been incorporated in the government's universal Childhood Immunisation Programme. This study aimed to evaluate rotavirus vaccine effectiveness against hospitalisation. METHODS: This case-control study was conducted in the 2014/2015 rotavirus season in six public hospitals. Hospitalised acute gastroenteritis patients meeting inclusion criteria were recruited and copies of their immunisation records were collected. Case-patients were defined as enrolled subjects with stool specimens obtained in the first 48h of hospitalisation that tested positive for rotavirus, whereas control-patients were those with stool specimens obtained in the first 48h of hospitalisation testing negative for rotavirus. Vaccine effectiveness for administration of at least one dose of either Rotarix(®) (GlaxoSmithKline Biologicals) or RotaTeq(®) (Merck Research Laboratories) was calculated as 1 minus the odds ratio for rotavirus vaccination history for case-patients versus control-patients. RESULTS: Among the 525 eligible subjects recruited, immunisation records were seen in 404 (77%) subjects. 31% (162/525 and 126/404) tested positive for rotavirus. In the 404 subjects assessed for vaccine effectiveness, 2.4% and 24% received at least 1 dose of either rotavirus vaccine in case- and control-patients respectively. The unmatched vaccine effectiveness against hospitalisation for administration of at least one dose of either rotavirus vaccines was 92% (95% confidence interval [CI]: 75%, 98%). The matched analyses by age only and both age and admission date showed 96% (95% CI: 72%, 100%) and 89% (95% CI: 51%, 97%) protection against rotavirus hospitalisation respectively. CONCLUSIONS: Rotavirus vaccine is highly effective in preventing hospitalisation from rotavirus disease in young Hong Kong children.

Efficacy, safety and immunogenicity of a human rotavirus vaccine (RIX4414) in Hong Kong children up to three years of age: a randomized, controlled trial.

BACKGROUND: A phase III, double-blind, randomized, controlled trial was conducted in Hong Kong to evaluate the efficacy, safety and immunogenicity of a human rotavirus vaccine, RIX4414 (Rotarix) against severe rotavirus gastroenteritis in children up to three years of age. METHODS: Healthy infants aged 6-12 weeks were enrolled between 08-December-2003 and 31-August-2005 and received two oral doses of either RIX4414 vaccine (N=1513) or placebo (N=1512) given 2 months apart. Vaccine efficacy was assessed from two weeks post-Dose 2 until the children were two and three years of age. Anti-rotavirus IgA seroconversion rate was calculated pre-vaccination and 1-2 months post-Dose 2 using ELISA (cut-off=20 U/mL) for 100 infants. Safety was assessed until the children were two years of age; serious adverse events (SAEs) were recorded throughout the study period. RESULTS: In children aged two and three years of life, vaccine efficacy against severe rotavirus gastroenteritis was 95.6% (95% CI: 73.1%-99.9%) and 96.1% (95% CI: 76.5%-99.9%), respectively. The seroconversion rate 1-2 months after the second dose of RIX4414 was 97.5% (95% CI: 86.8%-99.9%). At least one SAE was recorded in 439 and 477 infants who were administered RIX4414 and placebo, respectively (p-value=0.130). Six intussusception cases were reported (RIX4414=4; placebo=2) and none was assessed to be vaccine-related. CONCLUSION: RIX4414 was efficacious, immunogenic and safe in the prevention of rotavirus gastroenteritis for at least two years post-vaccination in Hong Kong children.

Chronic ulcerative gastroduodenitis as a first gastrointestinal manifestation of Hermansky-Pudlak syndrome in a 10-year-old child.

A 10-year-old Chinese boy who had a history of congenital thrombocytopathy presented with severe iron deficiency anemia secondary to chronic gastric inflammation and duodenal ulcerations. Subtle oculocutaneous albinism led to the finding of diminished dense bodies in the platelets under electron microscopy, hence the diagnosis of Hermansky-Pudlak syndrome (HPS). Biopsies from the stomach and duodenum revealed a lymphocytic infiltration in the submucosa, but H pylori infection was absent. The gastroduodenitis responded to the treatment with omeprazole while iron deficiency anemia was corrected by oral iron therapy. HPS is a rare cause of congenital bleeding disorder with multisystemic manifestations. Upper gastrointestinal involvement is rare and should be distinguished from a mere manifestation of the bleeding diathesis.

Hospital-based study of the economic burden associated with rotavirus diarrhea in Hong Kong.

BACKGROUND: Rotavirus infection is the most common cause of severe diarrhea in both developed and developing countries. METHODS: To estimate the economic burden associated with rotavirus infection in Hong Kong, we combined data on the disease burden of rotavirus-associated hospital admissions with detailed cost data for a subsample of 471 children with diarrhea admitted to hospitals. RESULTS: The annual total social cost and total direct medical cost for rotavirus-associated admissions were calculated as 4.3 US dollars and 4 million US dollars, respectively, by use of data collected during March 2001 to March 2003. The estimate of the direct medical costs was approximately 4-fold higher than a previous estimate; this difference largely reflects the greater disease burden identified through active disease surveillance conducted under the auspices of the Asian Rotavirus Surveillance Network. On average, families spent 120 US dollars when their child's admission was associated with rotavirus infection; this cost represents approximately 10% of the monthly salary of an unskilled or service worker. CONCLUSIONS: These data emphasize the potential for a safe and effective rotavirus vaccine to reduce the economic burden associated with rotavirus disease.

Estimates of rotavirus disease burden in Hong Kong: hospital-based surveillance.

BACKGROUND: We conducted prospective, hospital-based surveillance for rotavirus disease for a 2-year period at 4 of 12 public government (Hospital Authority [HA]) hospitals in Hong Kong. It has been estimated that HA hospitals provide 90% of inpatient care in Hong Kong. METHODS: Information was collected for children <5 years old who had a primary or secondary diagnosis of diarrhea or for whom a stool sample was tested for the presence of rotavirus (by enzyme immunoassay) or bacteria (by culture). Surveillance data were compared with routine discharge information from the HA's computerized Clinical Management System (CMS). RESULTS: During a 2-year period (1 April 2001 through 31 March 2003), 7391 children were admitted to the hospital with diarrhea or developed diarrhea during their hospital stay. Of these children, 5881 (80%) had a stool sample tested for the presence of rotavirus, and 30% were positive for rotavirus (representing 24% of all diarrhea-associated admissions). CMS data underreported the total percentage of diarrhea-associated admissions (15% vs. 20%) and the percentage of diarrhea-associated admissions that were the result of rotavirus infection (13% vs. 24%). Estimated rates of hospitalization for rotavirus infection (8.8 admissions/1000 children <5 years old and 18.4 admissions/1000 children <1 year old) were 4-fold higher than our previous estimates, which were determined on the basis of CMS data alone. We estimate that the cumulative risk of hospitalization with rotavirus diarrhea by age 5 years is 1 in 24. Combined active and passive (CMS) surveillance data indicate that 4.6% of all general pediatric admissions to HA hospitals in Hong Kong were associated with rotavirus infection. CONCLUSION: Our study combined passive surveillance data from all Hong Kong HA hospitals with active surveillance data from 4 sentinel hospitals. The estimates of rotavirus disease burden obtained will help emphasize the effect of this important disease and create awareness of the potential for rotavirus vaccines. The surveillance model developed could also be a powerful tool for monitoring the effect of a vaccine.