Estimating the Health and Economic Impact of Universal Varicella Vaccination in Jordan

Background

To evaluate the impact of adding universal varicella vaccination (UVV) to the existing childhood vaccination programme in Jordan, and identify the most cost-effective strategy.

Methods

A dynamic transmission model of varicella infection was calibrated to available varicella seroprevalence data within the region and validated against local epidemiological data. Local direct and indirect costs and healthcare utilization data were used. We considered the health and economic impact of one dose UVV administered concurrently with MMR at 12 months of age with 95% coverage, and two dose strategies with short (6 month) and long (4 year) intervals between First and Second dose. We took the societal perspective (direct and indirect costs) and discounted costs and QALYs by 3%/year to assess cost-effectiveness.

Results

The model estimated the current burden of varicella at 172,000 cases/year, an incidence rate of 2,200/100,000 persons. In the 5^th/25^th year after vaccination, all strategies substantially reduced total varicella incidence by 89.5%/96.6% (1 dose), 92.3%/98.0% (2 dose short), and 90.5%/98.3% (2 dose long), compared with no vaccine (Figure 1). In the absence of vaccination, an estimated $47.89 M ($28.81 M direct, $19.08 indirect) was spent annually on varicella treatment. The average annual total treatment costs over 25 years from the societal perspective were $4.01M (1 dose), $3.34M (2 dose short), and $3.43M (2 dose long). Considering a willingness to pay (WTP) threshold of $3,600 USD / QALY and the societal perspective, the 1 dose program was the most cost-effective with cost savings of $83.40 USD and health gain of 4.127 × 10⁻⁵ QALYs per person. 2 dose programs are similarly cost-saving and highly effective, compared with a scenario of no vaccination; however, moving incrementally from a 1 dose strategy, incremental cost-effectiveness ratios (ICERS) were $6.9M/QALY (short vs. 1 dose) and $13.5M/QALY (long vs. short), both well as above the WTP threshold. All strategies reached.

Conclusion

One or two dose UVV in Jordan will significantly reduce varicella disease burden and is cost saving relative to no vaccine over 25 years.

Disclosures

W. Hayajneh, Merck & Co., Inc.: Consultant, Consulting fee. J. Maalouf, Merck & Co., Inc.: Employee, Salary. B. Kuter, Merck & Co., Inc.: Employee, Salary.T. Weiss, Merck & Co., Inc.: Employee, Salary. V. Daniels, Merck & Co., Inc.: Employee, Salary. L. Wolfson, Merck & Co., Inc.: Employee, Salary.

Molecular typing of multiresistant Klebsiella pneumoniae isolated from children from northern Jordan

Twenty-nine clinical isolates of community acquired Klebsiella pneumoniae obtained from 17 children with malnutrition were characterized by antibiotic susceptibility, plasmid analysis, and random amplified polymorphic DNA (RAPD) techniques. Disc diffusion methodology was used to test the susceptibility of the isolates to 13 antibiotics: amoxycillin, cephapirin, ceftazidime, cefoxitin, cefotaxime, aztreonam, gentamicin, ciprofloxacin, chloramphenicol, erythromycin, nalidixic acid, trimethoprim and amoxycillin-clavulanic acid. All the isolates showed multiresistance patterns (15 patterns) ranging from resistance to two antibiotics to resistance to 10 antibiotics. All isolates were resistant to amoxycillin and erythromycin. Ten K. pneumoniae isolates producing extended-spectrum beta-lactamases (ESBLs) as evidenced by the double-disc diffusion synergy test were isolated sporadically from six patients. Six of these 10 isolates were hyperproducers of ESBL, which resulted in increased resistance to the beta-lactam-beta-lactamase inhibitor combination amoxycillin-clavulanic acid. Plasmid analysis showed plasmid ranging in size from 48 kilobases (kb) to 1.4 kb. All the 29 isolates shared the same plasmid 26 kb. There was a consistent relationship between antibiotype and plasmid profiles for each pair of isolates obtained from five individual patients. RAPD analysis using a single (10-mer) primer demonstrated that the isolates that have the same antibiotype and the same plasmid profile had different RAPD fingerprint patterns. These results demonstrate that the RAPD technique is better than antibiotype characterization and a plasmid analysis profile for typing K. pneumoniae as well as for revealing strain differences.

Respiratory syncytial virus infection in infants hospitalized with respiratory illness in northern Jordan

During the winter seasons of 1993 and 1994, a total of 256 nasopharyngeal aspirates (NPA) from infants aged less than 1 year old admitted to the pediatric ward of Princess Rahma Hospital, northern Jordan, with bronchiolitis and/or pneumonia, were tested for the presence of respiratory syncytial virus (RSV) using direct immunofluorescence assay (DFA) and cell culture (CC). Of the 256 specimens, 129 (50 per cent) were found positive by both DFA and CC, whereas 24 specimens (9 per cent) and 16 specimens (6 per cent) were found positive by DFA and CC, respectively. In an evaluation of the collected NPA specimens detected by DFA, a sensitivity of 89 per cent and a specificity of 78 per cent were demonstrated. These data suggest that virus isolation in CC is still important for the diagnosis of RSV, although DFA is a valuable, rapid diagnostic assay.

Viral gastroenteritis among young children in northern Jordan

During the summer months of 1992 and 1993, a total of 439 diarrhoeatic fecal specimens from infants and young children less than 3 years of age admitted to the pediatric ward of Princess Basma Teaching Hospital, northern Jordan were tested for the presence of viruses using direct electron microscopy (EM) and enzyme-linked immunosorbent assay (ELISA) for rotavirus. EM revealed rotaviruses in 83 (18.9 per cent) of cases, adenoviruses in five (1.1 per cent) cases, and small round viruses in three (0.68 per cent) cases. In contrast, the ELISA assay detected rotaviruses in 174 (39.6 per cent) of cases. In an evaluation of the collected diarrhoeatic fecal samples for rotavirus detected by ELISA, a sensitivity of 95.2 per cent and a specificity of 73.3 per cent was demonstrated.

Shigellosis in Jordanian children: a clinico-epidemiologic prospective study and susceptibility to antibiotics

During a 2-year prospective study of children hospitalized with gastroenteritis, shigellosis was detected in 66 cases (9 per cent of 726 admissions). The age group for peak shigella incidence was 1-4 years. The incidence increased from 8 per cent in 1991, to 11 per cent in 1992. Shigella flexneri was the most common isolate (65 per cent), followed by Shigella sonnei (17 per cent), Shigella boydi (11 per cent), and Shigella dysenteriae (7 per cent). At presentation, 44 per cent had watery diarrhoea, followed by dysentery during hospitalization in the majority of cases. Seizures occurred in 27 per cent of cases and preceded diarrhoea in 15 per cent. Most Shigella flexneri and dysenteriae strains were resistant to co-trimoxazole, ampicillin, tetracyclin, and chloramphenicol. Nalidixic acid, gentamicin and cefotaxime were the most effective antibacterial agents. Case fatality was 3 per cent associated with strains resistant to the antibiotics used initially in the treatment.