Performance of RT-PCR on Saliva Specimens Compared With Nasopharyngeal Swabs for the Detection of SARS-CoV-2 in Children: A Prospective Comparative Clinical Trial

The Infectious Diseases Society of America Guidelines on the Diagnosis of Coronavirus Disease 2019 (COVID-19): Molecular Diagnostic Testing

Accurate molecular diagnostic tests are necessary for confirming a diagnosis of coronavirus disease 2019 (COVID-19) and for identifying asymptomatic carriage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The number of available SARS-CoV-2 nucleic acid detection tests continues to increase as does the COVID-19 diagnostic literature. Thus, the Infectious Diseases Society of America (IDSA) developed an evidence-based diagnostic guideline to assist clinicians, clinical laboratorians, patients, and policymakers in decisions related to the optimal use of SARS-CoV-2 nucleic acid amplification tests. In addition, we provide a conceptual framework for understanding molecular diagnostic test performance, discuss nuances of test result interpretation in a variety of practice settings, and highlight important unmet research needs related to COVID-19 diagnostic testing. IDSA convened a multidisciplinary panel of infectious diseases clinicians, clinical microbiologists, and experts in systematic literature review to identify and prioritize clinical questions and outcomes related to the use of SARS-CoV-2 molecular diagnostics. Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assess the certainty of evidence and make testing recommendations. The panel agreed on 12 diagnostic recommendations. Access to accurate SARS-CoV-2 nucleic acid testing is critical for patient care, hospital infection prevention, and the public health response to COVID-19 infection. Information on the clinical performance of available tests continues to grow, but the quality of evidence of the current literature to support this updated molecular diagnostic guideline remains moderate to very low. Recognizing these limitations, the IDSA panel weighed available diagnostic evidence and recommends nucleic acid testing for all symptomatic individuals suspected of having COVID-19. In addition, testing is suggested for asymptomatic individuals with known or suspected contact with a COVID-19 case when the results will impact isolation/quarantine/personal protective equipment (PPE) usage decisions. Evidence in support of rapid testing and testing of upper respiratory specimens other than nasopharyngeal swabs, which offer logistical advantages, is sufficient to warrant conditional recommendations in favor of these approaches.

Comparative evaluation of saliva and nasopharyngeal swab for SARS-CoV-2 detection using RT-qPCR among COVID-19 suspected patients at Jigjiga, Eastern Ethiopia

BACKGROUND

Nasopharyngeal swab (NPS) remains the recommended sample type for Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) diagnosis. However, the collection procedure causes discomfort and irritation to the patients, lowering the quality of the sample and exposing healthcare workers to risk. Furthermore, there is also a shortage of flocked swabs and personnel protective equipment in low-income settings. Therefore, this necessitates an alternative diagnostic specimen. The purpose of this study was to evaluate the performance of saliva against NPS for SARS-CoV-2 detection using RT-qPCR among COVID-19 suspected patients at Jigjiga, Eastern Ethiopia.

METHODS

Comparative cross-sectional study was conducted from June 28 to July 30, 2022. A total of 227 paired saliva and NPS samples were collected from 227 COVID-19 suspected patients. Saliva and NPS samples were collected and transported to the Somali Regional Molecular Laboratory. Extraction was conducted using DaAn kit (DaAn Gene Co., Ltd China). Veri-Q RT-qPCR was used for amplification and detection (Mico BioMed Co, Ltd, Republic of Korea). The data were entered into Epi-data version 4.6 and analyzed using SPSS 25. McNemar's test was used to compare the detection rate. Agreement between NPS and saliva was performed using Cohen's Kappa. The mean and median of cycle threshold values were compared using paired t-tests and the correlation between cycle threshold values was measured using Pearson correlation coefficient. P value < 0.05 was considered statistically significant.

RESULTS

The overall positivity rate of SARS-CoV-2 RNA was 22.5% (95% CI 17-28%). Saliva showed higher sensitivity (83.8%, 95% CI, 73-94.5%) than NPS (68.9%, 95% CI 60.8-76.8%). The specificity of saliva was 92.6% (95% CI, 80.6% - 100%) compared to NPS (96.7%, 95% CI, 87% - 100%). The positive, negative, and overall percent agreement between NPS and saliva was 83.8%, 92.6%, and 91.2% respectively (κ = 0.703, 95% CI 0.58-0.825, P = 0.00). The concordance rate between the two samples was 60.8%. NPS showed a higher viral load than saliva. There was low positive correlation between the cycle threshold values of the two samples (r = 0.41, 95% CI -1.69 to -0.98, P >0.05).

CONCLUSION

Saliva showed a higher detection rate for SARS-CoV-2 molecular diagnosis than NPS and there was significant agreement between the two specimens. Therefore, saliva could be suitable and easily obtainable alternative diagnostic specimen for SARS-CoV-2 molecular diagnosis.

#Stayathome If You Have a Cold: High SARS-CoV-2 Salivary Viral Loads in Pediatric Patients with Nasopharyngeal Symptoms

The choice of the best SARS-CoV-2 detection approach is crucial to predict which children with SARS-CoV-2 are at high risk of spreading the virus in order to manage public health measures and policies. In this prospective observational study of 35 children admitted to the Pediatric Emergency Departments of two tertiary hospitals in Northern Italy who tested positive for SARS-CoV-2 by standard RT-PCR in nasopharyngeal swab (NPS), we evaluated their presenting symptoms according to their salivary viral load (SVL) determined by droplet digital PCR (ddPCR). Despite an overall low concordance between SARS-CoV-2 detected by salivary ddPCR and NPS RT-PCR (54.3%), when only patients with nasopharyngeal symptoms were analyzed, the sensitivity of ddPCR in saliva specimens increased to 71.4%, and over half of these patients had high SVL (>105 copies/mL), which was significantly more frequent than in children without nasopharyngeal symptoms (57.1% vs. 14.3%, OR = 8, CI 95% 1.28−50.03, p = 0.03). All asymptomatic children had low SVL values. Our findings support the hypothesis that children with nasopharyngeal symptoms are at higher risk of spreading SARS-CoV-2 due to their high SVL and, conversely, asymptomatic children are unlikely to spread the virus due to their low SVL, regardless of their NPS positivity.

Comparison of Nasopharyngeal and Saliva Swab Nucleic Acid Amplification and Rapid Antigen Testing To Detect Omicron SARS-CoV-2 Variant of Concern: a Prospective Clinical Trial (OMICRON)

In November 2021, the World Health Organization declared the Omicron variant (B.1.1.519) a variant of concern. Since then, worries have been expressed regarding the ability of usual diagnostic tests to detect the Omicron variant. In addition, some recently published data suggested that the salivary reverse transcription (RT)-PCR might perform better than the current gold standard, nasopharyngeal (NP) RT-PCR. In this study, we aimed to compare the sensitivities of nasopharyngeal and saliva RT-PCR and assess the diagnostic performances of rapid antigen testing (RAT) in nasopharyngeal and saliva samples. We conducted a prospective clinical study among symptomatic health care professionals consulting the occupational health service of our hospital for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) screening and hospitalized patients in internal medicine/intensive care wards screened for SARS-CoV-2 with COVID-19-compatible symptoms. A composite outcome considering NP PCR and/or saliva PCR was used as a reference standard to define COVID-19 cases. A total of 475 paired NP/saliva specimens have been collected with a positivity rate of 40% (n = 192). NP and salivary RT-PCR exhibited sensitivities of 98% (95% CI, 94 to 99%) and 87% (95% CI, 81 to 91%), respectively, for outpatients (n = 453) and 94% (95% CI, 72 to 99%) and 69% (95% CI, 44 to 86%), respectively, for hospitalized patients (n = 22). Nasopharyngeal rapid antigen testing exhibited much lower diagnostic performances (sensitivity of 66% and 31% for outpatients and inpatients, respectively), while saliva RAT showed a sensitivity of less than 5% in both groups. Nasopharyngeal RT-PCR testing remains the gold standard for SARS-CoV-2 Omicron variant screening. Salivary RT-PCR can be used as an alternative in case of contraindication to perform NP sampling. The use of RAT should be limited to settings where access to molecular diagnostic methods is lacking. IMPORTANCE The Omicron variant of concern spread rapidly since it was first reported in November 2021 and currently accounts for the vast majority of new infections worldwide. Recent reports suggest that saliva sampling might outweigh nasopharyngeal sampling for the diagnosis of the Omicron variant. Nevertheless, data investigating the best diagnostic strategy specifically for the Omicron variant of concern remain scarce. This study fills this gap in current knowledge and elucidates the question of which strategy to use in which patient. It provides a new basis for further improving COVID-19 screening programs and managing patients suspected to have COVID-19.

Direct Nasal Swab for Rapid Test and Saliva as an Alternative Biological Sample for RT-PCR in COVID-19 Diagnosis

Accurate and early diagnoses are prerequisites for prompt treatment. For coronavirus disease 2019 (COVID-19), it is even more crucial. Currently, choice of methods include rapid diagnostic tests and reverse transcription polymerase chain reaction (RT-PCR) using samples mostly of respiratory origin and sometimes saliva. We evaluated two rapid diagnostic tests with three specimen types using viral transport medium (VTM) containing naso-oropharyngeal (NOP) swabs, direct nasal and direct nasopharyngeal (NP) samples from 428 prospective patients. We also performed RT-PCR for 428 NOP VTM and 316 saliva samples to compare results. The sensitivity of the SD Biosensor Standard Q COVID-19 antigen (Ag) test kit drastically raised from an average of 65.55% (NOP VTM) to 85.25% (direct nasal samples), while RT-PCR was the gold standard. For the CareStart kit, the sensitivity was almost similar for direct NP swabs; the average was 84.57%. The specificities were ≥95% for both SD Biosensor Standard Q and CareStart COVID-19 Ag tests in all platforms. The kits were also able to detect patients with different variants as well. Alternatively, RT-PCR results from saliva and NOP VTM samples showed high sensitivities of 96.45% and 95.48% with respect to each other as standard. The overall results demonstrated high performance of the rapid tests, indicating the suitability for regular surveillance at clinical facilities when using direct nasal or direct NP samples rather than NOP VTM. Additionally, the analysis also signifies not showed that RT-PCR of saliva can be used as an choice of method to RT-PCR of NOP VTM, providing an easier, non-invasive sample collection method. IMPORTANCE There are several methods for the diagnosis of coronavirus disease 2019 (COVID-19), and the choice of methods depends mostly on the resources and level of sensitivity required by the user and health care providers. Still, reverse transcription polymerase chain reaction (RT-PCR) has been chosen as the best method using direct naso-oropharyngeal swabs. There are also other methods of fast detection, such as rapid diagnostic tests (RDTs), which offer result within 15 to 20 min and have become quite popular for self-testing and in the clinical setting. The major drawback of the currently used RT-PCR method is compliance, as it may cause irritation, and patients often refuse to test in such a way. RDTs, although inexpensive, suffer from low sensitivity due to technical issues. In this article, we propose saliva as a noninvasive source for RT-PCR samples and evaluate various specimen types at different times after infection for the best possible output from COVID-19 rapid tests.

Oral saliva swab reverse transcription PCR for Covid-19 in the paediatric population

OBJECTIVES

To evaluate the performance of oral saliva swab (OSS) reverse transcription PCR (RT-PCR) compared with RT-PCR and antigen rapid diagnostic test (Ag-RDT) on nasopharyngeal swabs (NPS) for SARS-CoV-2 in children.

DESIGN

Cross-sectional multicentre diagnostic study.

SETTING

Study nested in a prospective, observational cohort (EPICO-AEP) performed between February and March 2021 including 10 hospitals in Spain.

PATIENTS

Children from 0 to 18 years with symptoms compatible with Covid-19 of ≤5 days of duration were included. Two NPS samples (Ag-RDT and RT-PCR) and one OSS sample for RT-PCR were collected.

MAIN OUTCOME

Performance of Ag-RDT and RT-PCR on NPS and RT-PCR on OSS sample for SARS-CoV-2.

RESULTS

1174 children were included, aged 3.8 years (IQR 1.7-9.0); 73/1174 (6.2%) patients tested positive by at least one of the techniques. Sensitivity and specificity of OSS RT-PCR were 72.1% (95% CI 59.7 to 81.9) and 99.6% (95% CI 99 to 99.9), respectively, versus 61.8% (95% CI 49.1 to 73) and 99.9% (95% CI 99.4 to 100) for the Ag-RDT. Kappa index was 0.79 (95% CI 0.72 to 0.88) for OSS RT-PCR and 0.74 (95% CI 0.65 to 0.84) for Ag-RDT versus NPS RT-PCR.

CONCLUSIONS

RT-PCR on the OSS sample is an accurate option for SARS-CoV-2 testing in children. A less intrusive technique for younger patients, who usually are tested frequently, might increase the number of patients tested.

Salivary testing for SARS-CoV-2 in the pediatric population: a diagnostic accuracy study

BACKGROUND

Accurate and timely testing for SARS-CoV-2 in the pediatric population is crucial to control the COVID-19 pandemic; saliva testing has been proposed as a less invasive alternative to nasopharyngeal swabs. We sought to compare the detection of SARS-CoV-2 using saliva versus nasopharyngeal swab in the pediatric population, and to determine the optimum time of testing for SARS-CoV-2 using saliva.

METHODS

We conducted a longitudinal diagnostic study in Ottawa, Canada, from Jan. 19 to Mar. 26, 2021. Children aged 3-17 years were eligible if they exhibited symptoms of COVID-19, had been identified as a high-risk or close contact to someone confirmed positive for SARS-CoV-2 or had travelled outside Canada in the previous 14 days. Participants provided both nasopharyngeal swab and saliva samples. Saliva was collected using a self-collection kit (DNA Genotek, OM-505) or a sponge-based kit (DNA Genotek, ORE-100) if they could not provide a saliva sample into a tube.

RESULTS

Among 1580 paired nasopharyngeal and saliva tests, 60 paired samples were positive for SARS-CoV-2. Forty-four (73.3%) were concordant-positive results and 16 (26.6%) were discordant, among which 8 were positive only on nasopharyngeal swab and 8 were positive only on saliva testing. The sensitivity of saliva was 84.6% (95% confidence interval 71.9%-93.1%).

INTERPRETATION

Salivary testing for SARS-CoV-2 in the pediatric population is less invasive and shows similar detection of SARS-CoV-2 to nasopharyngeal swabs. It may therefore provide a feasible alternative for diagnosis of SARS-CoV-2 infection in children.

Saliva for molecular detection of SARS‐CoV ‐2 in preschool and school‐age children

SARS‐CoV‐2 diagnosis is a cornerstone for the management of coronavirus disease 2019 (COVID‐19). Numerous studies have assessed saliva performance over nasopharyngeal sampling (NPS), but data in young children are still rare. We explored saliva performance for SARS‐CoV‐2 detection by RT‐PCR according to the time interval from initial symptoms or patient serological status. We collected 509 NPS and saliva paired samples at initial diagnosis from 166 children under 12 years of age (including 57 children under 6), 106 between 12 and 17, and 237 adults. In children under 12, overall detection rate for SARS‐CoV‐2 was comparable in saliva and NPS, with an overall agreement of 89.8%. Saliva sensitivity was significantly lower than that of NPS (77.1% compared to 95.8%) in pre‐school and school‐age children but regained 96% when considering seronegative children only. This pattern was also observed to a lesser degree in adolescents but not in adults. Sensitivity of saliva was independent of symptoms, in contrary to NPS, whose sensitivity decreased significantly in asymptomatic subjects. Performance of saliva is excellent in children under 12 at early stages of infection. This reinforces saliva as a collection method for early and unbiased SARS‐CoV‐2 detection and a less invasive alternative for young children.

Principales modificaciones en la guía de práctica clínica «COVID-19 en pediatría»

Presentamos el resumen de las principales modificaciones surgidas en la guía de práctica clínica «COVID-19 en Pediatría» entre su versión inicial publicada en el año 2021 y la publicada en el año 2022. El documento se ha elaborado siguiendo los pasos estructurados de la medicina basada en la evidencia e incorporando el sistema GRADE para realizar síntesis de la evidencia, con valoración de su calidad y, cuando se consideró apropiado, emitir recomendaciones jerarquizadas (en función de la calidad de la evidencia, los valores y preferencias, el balance entre beneficios, riesgos y costes, la equidad y la factibilidad). En esta actualización se incluyen también los cambios recomendados por los revisores externos.

Se sintetizan las principales modificaciones en los siguientes apartados: epidemiología, clínica, diagnóstico, prevención, tratamiento y vacunas. En el conjunto del conocimiento alcanzado a lo largo del primer año de pandemia, las publicaciones durante el segundo año añaden nuevos datos, sin que en muchas de las áreas se produzcan modificaciones sustanciales. Los principales cambios acaecen en el campo de investigación de las vacunas. Esta actualización finaliza en diciembre de 2021, coincidiendo con el aumento de la infección por ómicron, por lo que será necesario una futura actualización del documento.

Main changes in the "COVID-19 in paediatrics" clinical practice guideline

We present a summary of the main modifications to the “COVID-19 in Paediatrics” clinical practice guideline made from its initial version, published in 2021, and the version published in 2022. The document was developed following the structured steps of evidence-based medicine and applying the GRADE system to synthesize the evidence, assess its quality and, when appropriate, issue graded recommendations (based on the quality of the evidence, values and preferences, the balance between benefits, risks and costs, equity and feasibility). This update also includes the modifications proposed by external reviewers.

We summarised the main modifications in the following sections: epidemiology, clinical features, diagnosis, prevention, treatment and vaccines. In relation to the body of knowledge achieved in the first year of the pandemic, the literature published in the second year contributed additional data, but without substantial modifications in many the areas. The main changes took place in the field of vaccine research. This update was completed in December 2021, coinciding with the emergence of infections by the omicron variant, so the document will need to be updated in the future.

Saliva as a diagnostic specimen for SARS-CoV-2 detection: a scoping review

Objectives

This scoping review aims to summarize the diagnostic value of saliva assessed from current studies that (1) compare its performance in reverse transcriptase‐polymerase chain reaction testing to nasopharyngeal swabs, (2) evaluate its performance in rapid and point‐of‐care COVID‐19 diagnostic tests, and (3) explore its use as a specimen for detecting anti‐SARS‐CoV‐2 antibodies.

Materials and Methods

A systematic search was performed on the following databases: Medline and Embase (Ovid), World Health Organization, Centers for Disease Control and Prevention, and Global Health (Ovid) from January 2019 to September 2021. Of the 657 publications identified from the searches, n = 146 articles were included in the final scoping review.

Results

Our findings showcase that salivary samples exceed nasopharyngeal swabs in detecting SARS‐CoV‐2 using reverse transcriptase‐polymerase chain reaction testing in several studies. A select number of rapid antigen and point‐of‐care tests from the literature were also identified capable of high detection rates using saliva. Moreover, anti‐SARS‐CoV‐2 antibodies have been shown to be detectable in saliva through biochemical assays.

Conclusion

We highlight the potential of saliva as an all‐rounded specimen in detecting SARS‐CoV‐2. However, future large‐scale clinical studies will be needed to support its widespread use as a non‐invasive clinical specimen for COVID‐19 testing.

High SARS-CoV-2 household transmission rates detected by dense saliva sampling

BACKGROUND

Understanding the dynamics of SARS-CoV-2 household transmission is important for adequate infection control measures in this ongoing pandemic.

METHODS

Households were enrolled upon a PCR-confirmed index case between October and December 2020, prior to the COVID-19 vaccination program. Saliva samples were obtained by self-sampling at day 1, 3, 5, 7, 10, 14, 21, 28, 35, and 42 from study inclusion. Nasopharyngeal swabs (NPS) and oropharyngeal swabs (OPS) were collected by the research team at day 7 and capillary blood samples at day 42. Household secondary attack rate (SAR) and per-person SAR were calculated based on at least one positive saliva, NPS, OPS, or serum sample. Whole genome sequencing was performed to investigate the possibility of multiple independent SARS-CoV-2 introductions within a household.

RESULTS

Eighty-five households were included consisting of 326 (unvaccinated) individuals. Comparable numbers of secondary cases were identified by saliva (133/241; 55.2%) and serum (127/213; 59.6%). The household SAR was 88.2%. The per-person SAR was 64.3%. The majority of the secondary cases tested positive in saliva at day 1 (103/150; 68.7%). Transmission from index case to household member was not affected by age or the nature of their relationship. Phylogenetic analyses suggested a single introduction for the investigated households.

CONCLUSION

Households have a pivotal role in SARS-CoV-2 transmission. By repeated saliva self-sampling combined with NPS, OPS, and serology, we found the highest SARS-CoV-2 household transmission rates reported to date. Salivary (self-)sampling of adults and children is suitable and attractive for near real-time monitoring of SARS-CoV-2 transmission in this setting.

SARS-CoV-2 Saliva Mass Screening in Primary Schools: A 10-Week Sentinel Surveillance Study in Munich, Germany

Representative, actively collected surveillance data on asymptomatic SARS-CoV-2 infections in primary schoolchildren remain scarce. We evaluated the feasibility of a saliva mass screening concept and assessed infectious activity in primary schools. During a 10-week period from 3 March to 21 May 2021, schoolchildren and staff from 17 primary schools in Munich participated in the sentinel surveillance, cohort study. Participants were tested using the Salivette® system, testing was supervised by trained school staff, and samples were processed via reverse transcription quantitative polymerase chain reaction (RT-qPCR). We included 4433 participants: 3752 children (median age, 8 [range, 6-13] years; 1926 girls [51%]) and 681 staff members (median age, 41 [range, 14-71] years; 592 women [87%]). In total, 23,905 samples were processed (4640 from staff), with participants representing 8.3% of all primary schoolchildren in Munich. Only eight cases were detected: Five out of 3752 participating children (0.13%) and three out of 681 staff members (0.44%). There were no secondary cases. In conclusion, supervised Salivette® self-sampling was feasible, reliable, and safe and thus constituted an ideal method for SARS-CoV-2 mass screenings in primary schoolchildren. Our findings suggest that infectious activity among asymptomatic primary schoolchildren and staff was low. Primary schools appear to continue to play a minor role in the spread of SARS-CoV-2 despite high community incidence rates.

Recent findings and applications of biomedical engineering for COVID-19 diagnosis: a critical review

COVID-19 is one of the most severe global health crises that humanity has ever faced. Researchers have restlessly focused on developing solutions for monitoring and tracing the viral culprit, SARS-CoV-2, as vital steps to break the chain of infection. Even though biomedical engineering (BME) is considered a rising field of medical sciences, it has demonstrated its pivotal role in nurturing the maturation of COVID-19 diagnostic technologies. Within a very short period of time, BME research applied to COVID-19 diagnosis has advanced with ever-increasing knowledge and inventions, especially in adapting available virus detection technologies into clinical practice and exploiting the power of interdisciplinary research to design novel diagnostic tools or improve the detection efficiency. To assist the development of BME in COVID-19 diagnosis, this review highlights the most recent diagnostic approaches and evaluates the potential of each research direction in the context of the pandemic.

Feasibility and Diagnostic Accuracy of Saliva-Based SARS-CoV-2 Screening in Educational Settings and Children Aged <12 Years

Children have been disproportionately affected during the COVID-19 pandemic. We aimed to assess a saliva-based algorithm for SARS-CoV-2 testing to be used in schools and childcare institutions under pandemic conditions. A weekly SARS-CoV-2 sentinel study in primary schools, kindergartens, and childcare facilities was conducted over a 12-week-period. In a sub-study covering 7 weeks, 1895 paired oropharyngeal and saliva samples were processed for SARS-CoV-2 rRT-PCR testing in both asymptomatic children (n = 1243) and staff (n = 652). Forty-nine additional concurrent swab and saliva samples were collected from SARS-CoV-2 infected patients (patient cohort). The Salivette^® system was used for saliva collection and assessed for feasibility and diagnostic performance. For children, a mean of 1.18 mL saliva could be obtained. Based on results from both cohorts, the Salivette^® testing algorithm demonstrated the specificity of 100% (95% CI 99.7–100) and sensitivity of 94.9% (95% CI 81.4–99.1) with oropharyngeal swabs as reference. Agreement between sampling systems was 100% for moderate to high viral load situations (defined as Ct-values <33 from oropharyngeal swabs). Comparative analysis of Ct-values derived from saliva vs. oropharyngeal swabs demonstrated a significant difference (mean 4.23; 95% CI 2.48–6.00). In conclusion, the Salivette^® system proved to be an easy-to-use, safe and feasible saliva collection method and a more pleasant alternative to oropharyngeal swabs for SARS-CoV-2 testing in children aged 3 years and above.

Diagnostic Accuracy of SARS-CoV-2 Rapid Antigen Detection Testing in Symptomatic and Asymptomatic Children in the Clinical Setting

Antigen-based rapid diagnostic tests (RDTs) are used in children despite the lack of data. We evaluated the diagnostic performance of the Panbio-COVID-19 Ag Rapid Test Device (P-RDT) in children. Symptomatic and asymptomatic participants 0 to 16 years old had two nasopharyngeal swabs (NPS) for both reverse transcription-PCR (RT-PCR) and P-RDT. A total of 822 participants completed the study, of which 533 (64.9%) were symptomatic. Among the 119 (14.5%) RT-PCR-positive patients, the P-RDT sensitivity was 0.66 (95% confidence interval [CI] 0.57 to 0.74). Mean viral load (VL) was higher among P-RDT-positive patients than negative ones (P < 0.001). Sensitivity was 0.91 in specimens with VL of >1.0E6 IU/ml (95% CI 0.83 to 0.99) and decreased to 0.75 (95% CI 0.66 to 0.83) for specimens >1.0E3 IU/ml. Among symptomatic participants, the P-RDT displayed a sensitivity of 0.73 (95% CI 0.64 to 0.82), which peaked at 1.00 at 2 days post-onset of symptoms (DPOS) (95% CI 1.00 to 1.00), then decreased to 0.56 (95% CI 0.23 to 0.88) at 5 DPOS. There was a trend toward lower P-RDT sensitivity in symptomatic children <12 years (0.62 [95% CI 0.45 to 0.78]) versus ≥12 years (0.80 [95% CI 0.69 to 0.91]; P = 0.09). In asymptomatic participants, the P-RDT displayed a sensitivity of 0.43 (95% CI 0.26 to 0.61). Specificity was 1.00 in symptomatic and asymptomatic children (95% CI 0.99 to 1.00). The overall 73% and 43% sensitivities of P-RDT in symptomatic and asymptomatic children, respectively, was below the 80% cutoff recommended by the World Health Organization. We observed a correlation between VL and P-RDT sensitivity, as well as variation of sensitivity according to DPOS, a major determinant of VL. These data highlight the limitations of RDTs in children, with the potential exception in early symptomatic children ≥12yrs.