Determining effectiveness of rotavirus vaccine by immunochromatography and reverse transcriptase polymerase chain reaction: A comparison.

INTRODUCTION: Because of the large animal reservoirs and reassortment capacity of rotaviruses (RVs) that pose the possibilities of waning the effectiveness of RV-vaccines, it remains essential to monitor vaccine effectiveness (VE) regularly. Although reverse transcription polymerase chain reaction (RT-PCR) remains sensitive for RV detection, physicians, especially in Japan, frequently use immunochromatography (IC)-based kits for RV diagnosis. Recently, IC is being used to calculate VE also. Herein, we investigated the validity of VEs determined by IC compared to that by RT-PCR during an outbreak in Shizuoka Prefecture, Japan.

METHODS: RVs in the stool or rectal swabs from children with acute gastroenteritis (AGE) were tested first by IC in the clinic and then by RT-PCR in the laboratory. A test-negative study design was used to examine VE.

RESULTS: Although the specificity of IC assay revealed 100%, its sensitivity remained weaker (67%) than that of RT-PCR that increased up to 88% depending on disease severity. VE assessed by IC remained stronger than that by RT-PCR: 79% (95% CI: 39-93%) by IC, and 58% (95% CI: -20% to 90%) by RT-PCR. However, VEs by IC and RT-PCR appeared almost similar in higher disease severity: 81.5% (95% CI: 40-94%) by IC and 72% (95% CI: 7-92%) by RT-PCR at severity ≥7, while 97.5% (95% CI: 77-99.7%) by IC and 92% (95% CI: 58-98%) by RT-PCR at severity ≥11. We showed that RV-vaccinated children had 80% [OR = 0.192 (95% CI: 0.052-0.709) less chance to be detected by IC.

CONCLUSION: Although the sensitivity and specificity of IC differ by brand type, generally, IC is not as sensitive as RT-PCR. Despite the VEs remain higher by IC, it looks comparable with that of RT-PCR in severe cases implying that VEs evaluated by IC against severe illness remain useful for VE-monitoring.