Accuracy and efficacy of pre-dengue vaccination

A convenient, highly specific and highly sensitive dengue pre-vaccination test is still needed. The OnSite Dengue IgG Rapid Diagnostic Test (RDT) is a new rapid diagnostic test specifically designed for pre-vaccination screening.

Our objective was to retrospectively assess the efficacy of a tetravalent dengue vaccine (CYD-TDV) in participants determined to be seropositive for dengue by the OnSite IgG RDT and to evaluate the performance of the assay.

This was an add-on study using pre-vaccination samples from two CYD-TDV efficacy trials conducted in five countries in the Asia-Pacific region (NCT01373281) and five countries in Latin America (NCT01374516). Baseline dengue serostatus was determined by OnSite IgG RDT on samples from the immunogenicity subsets of both assays.

In participants who tested positive, we calculated the efficacy of the CYD-TDV vaccine against virologically confirmed symptomatic dengue fever (VCD) over 25 months and against hospitalization with VCD over 72 months of follow-up after the first vaccination.

We used a benchmark algorithm to determine the baseline dengue serostatus for each sample, and the sensitivity and specificity of the OnSite IgG RDT were calculated. The analyzes were carried out on the whole population (aged 2 to 16), as well as on those aged 6 or over and those aged 9 or over.

Of the 3983 participants in the immunogenicity subsets of the CYD14 and CYD15 efficacy trials, 3962 had complete reference dengue test results allowing classification of baseline serostatus and 3833 had sufficient remaining serum samples for evaluation with the OnSite IgG RDT.

Of the samples tested, 2486 (64.9%) of 3833 were positive for the OnSite IgG TDR. In participants aged 2–16 years positive for the OnSite IgG RDT, vaccine efficacy was 84·1% (95% CI 71·6–91·1) against symptomatic VCD and 69·2% ( 38·8–84· 5) versus hospitalization with VCD, with similar results in those aged 6 years or older and those aged 9 years or older.

The OnSite IgG RDT showed very high sensitivity (91 1%, 89 9–92 1) and high specificity (92 8%, 91 2–94 2) in participants aged 2 to 16 years, with specificity in people aged 9 years or older (96 6%, 94 9–97 8).

On-site IgG RDT should provide a valuable tool for screening for previous dengue infection at the time of vaccination. In people who were positive for the OnSite IgG RDT, the efficacy of the CYD-TDV vaccine was high in all three age groups.