Influenza Diagnosis in Clinical Practice: Comparing Rapid Antigen Tests and RT-PCR with Age-Stratified Results

Year 2025, Volume: 15 Issue: 3, 359 - 363, 05.01.2026

İhsan Topaloğlu , Gülfem Özduygu Çağrı Atasoy , Talha Karahan , Gizem Tükenmez , Murat Karameşe , Kübra Nur Yılmaz Gülfem Nur Yıldız Nurullah Çiftçi

Abstract

Aim: To evaluate the diagnostic sensitivity of a commercially available rapid influenza antigen test in comparison to reverse-transcription polymerase chain reaction (RT– PCR), and to examine the impact of age on test performance.
Material and Methods: We conducted a single-center, retrospective diagnostic sensitivity study at Kafkas University Faculty of Medicine Hospital between January and April 2025. Consecutive symptomatic patients were tested using multiplex RT-PCR on nasopharyngeal swabs. The index test (SD Bioline Influenza A/B RADT) was only performed on RT-PCR-positive samples following the manufacturer’s instructions. The primary endpoint was the sensitivity of the SD Bioline Influenza A/B RADT for influenza A and B overall and by age group (pediatric <18 years, adult ≥18 years). We also documented cases where RT-PCR-confirmed influenza A samples produced influenza B readings on the RADT and compared their frequency by age group. Statistics: sensitivity and 95% confidence intervals (CIs) were calculated using the Wilson method; subgroup comparisons employed Fisher’s exact test. As per the study design, specificity, positive predictive value (PPV), and negative predictive value (NPV) could not be estimated.
Results: Out of 531 symptomatic cases, 92 tested positive via RTPCR (influenza A: 78; influenza B: 14). The RADT exhibited an overall sensitivity of 81. 5%, with subtype-specific sensitivities of 78. 2% for influenza A and 100% for influenza B. Sensitivity was higher in children than in adults (92. 9% vs. 74. 0%, p=0. 03). A small subset of RT-PCR-confirmed influenza A samples produced influenza B readings on the RADT; none of these were RT-PCR-positive for influenza B. Specifically, in 11 of 78 RT-PCR-confirmed influenza A samples (14. 1%; 95% CI 8. 8.1–23. 5), the RADT read influenza B; none of these 11 samples were RT-PCR-positive for influenza B.
Conclusion: Rapid antigen tests are reliable tools for diagnosing influenza in children, given their higher sensitivity in this group. However, in adults, the lower sensitivity means that negative results should be interpreted with caution and may require confirmation by RT-PCR.

Keywords

influenza virus , RT-PCR diagnosis , rapid antigen test , age-related diagnostic performance; age-dependent immune response

References

• 1. Uyeki TM, Bernstein HH, Bradley JS, Englund JA, File TM, Fry AM, et al. Clinical practice guidelines by the Infectious Diseases Society of America:2018 update on diagnosis, treatment, chemoprophylaxis, and institutional outbreak management of seasonal influenza. Clin Infect Dis. 2019;68(6):895–902.
• 2. World Health Organization. (2019). WHO guidelines for rapid diagnostic testing for influenza. https://www. who. int/ publications/i/item/rapid-influenza-diagnostic-tests
• 3. Chartrand C, Leeflang MMG, Minion J, Brewer T, Pai M. Accuracy of rapid influenza diagnostic tests: A meta-analysis. Ann Intern Med. 2012;156(7):500–511.
• 4. Irving SA, Vandermause MF, Shay DK, Belongia EA. Comparison of nasal and nasopharyngeal swabs for influenza detection in adults. Clin Med Res. 2012;10(4):215–218.
• 5. Bruning AHL, van Dijk K, van Eijk HW, Koen G, van Woensel JB, Kruisinga FH, et al. Evaluation of a rapid antigen detection test for influenza A and B virus diagnosis. Diagnostics. 2017;7(4):65.
• 6. Chen Y, Huang Z, Jiang L, Zhu W, Liao C, Xu Y, et al. Clinical evaluation of a rapid influenza diagnostic test for detection of influenza A and B viruses in children in a tertiary care hospital in China. J Infect Dev Ctries. 2021;15(4):507–512.
• 7. Centers for Disease Control and Prevention. (2023). Influenza diagnostic testing during the 2022–2023 season. https://www. cdc.gov/flu/professionals/diagnosis/index.htm
• 8. Ryu SW, Suh IB, Yang PG, Oh HB, Kim JY, Baek LJ. Comparison of rapid influenza diagnostic tests for influenza A and B viruses with real-time RT-PCR. J Clin Virol. 2019;117:27–31.
• 9. Ryu SW, Suh IB, Ryu SM, Shin KS, Kim HS, Kim J, et al. Comparison of three rapid influenza diagnostic tests with digital readout systems and one conventional rapid influenza diagnostic test. J Clin Lab Anal. 2018;32(2):e22234.
• 10. Merckx J, Wali R, Schiller I, Caya C, Gore GC, Chartrand C, et al. Diagnostic accuracy of novel and traditional rapid tests for influenza infection compared with RT-PCR. a systematic review and meta-analysis. Ann Intern Med. 2017;167(6):394409.