Diagnosis of COVID-19 infection in children: Less nasopharyngeal swabs, more saliva

Investigation of the diagnostic performance of the SARS-CoV-2 saliva antigen test: A meta-analysis

BACKGROUND

The COVID-19 pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Rapid identification and isolation of patients with COVID-19 are critical strategies to contain COVID-19. The saliva antigen test has the advantages of noninvasiveness and decreased transmission risk to health-care professionals. This meta-analysis investigated the diagnostic accuracy of the saliva antigen test for SARS-CoV-2.

METHODS

We searched for relevant studies in PubMed, Embase, Cochrane Library, and Biomed Central. Studies evaluating the diagnostic accuracy of saliva antigen tests for SARS-CoV-2 were included. The data of the included studies were used to construct a 2 × 2 table on a per patient basis. The overall sensitivity and specificity of saliva antigen tests were determined using a bivariate random-effects model.

RESULTS

Nine studies enrolling 9842 patients were included. The meta-analysis generated a pooled sensitivity of 65.3% and a pooled specificity of 99.7%. A subgroup analysis of the studies performing the chemiluminescent enzyme immunoassay (CLEIA) for participants from airports and public health centers revealed a pooled sensitivity of 93.6%.

CONCLUSION

Our findings demonstrated that the saliva antigen test performed using CLEIA exhibited higher sensitivity for the detection of SARS-CoV-2. Therefore, the saliva antigen test performed using CLEIA might be an effective and noninvasive screening tool for SARS-CoV-2.

Monitoring of SARS-CoV-2 circulation using saliva testing in school children in Rome, Italy

Objectives

To describe the trend of SARS-CoV-2 RNA in saliva samples from children attending nine schools in Rome in the local surveillance unit RM3 during the period of September 2021-March 2022, in parallel with the trend of SARS-CoV-2 RNA observed in nasopharyngeal swabs (NPSs) from the population in the same catchment area that was routinely tested at our laboratory in the same period.

Methods

Saliva samples were collected using the Copan LolliSponge^TM device and analyzed by Aptima® SARS-CoV-2 Assay on the Panther® System. NPSs were tested using either Aptima® SARS-CoV-2 Assay or Alinity m SARS-CoV-2 Assay.

Results

The percentage of positivity in the two populations was different; of the 2222 saliva samples from students, 0.99% had positive results, whereas the percentage was higher (33.43%) in the 8994 NPSs representing the population from local surveillance unit RM3. Interestingly, the trend of SARS-CoV-2 RNA in saliva samples from students was consistent with that observed in NPSs from the population in same catchment area, although with peaks slightly anticipated.

Conclusion

Overall, screening of saliva in the schools represents a good system to monitor SARS-CoV-2 circulation in the population, allowing early detection and quick isolation of students who are asymptomatic with positive test results and thus prevention of virus transmission.

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

BACKGROUND

Saliva reverse transcriptase-Polymerase chain reaction (RT-PCR) is an attractive alternative for the detection of severe acute respiratory syndrome coronavirus 2 in adults with less known in children.

METHODS

Children with coronavirus disease 2019 symptoms were prospectively enrolled in a 1-month comparative clinical trial of saliva and nasopharyngeal (NP) RT-PCR. Detection rates and sensitivities of saliva and NP RT-PCR were compared as well as discordant NP and saliva RT-PCR findings including viral loads (VLs).

RESULTS

Of 405 patients enrolled, 397 patients had 2 tests performed. Mean age was 12.7 years (range, 1.2-17.9). Sensitivity of saliva was 85.2% (95% confidence interval: 78.2%-92.1%) when using NP as the standard; sensitivity of NP was 94.5% (89.8%-99.2%) when saliva was considered as the standard. For a NP RT-PCR VL threshold of ≥103 and ≥104 copies/mL, sensitivity of saliva increases to 88.7% and 95.2%, respectively. Sensitivity of saliva and NP swabs was, respectively, 89.5% and 95.3% in patient with symptoms less than 4 days (P = 0.249) and 70.0% and 95.0% in those with symptoms ≥4-7 days (P = 0.096). The 15 patients who had an isolated positive NP RT-PCR were younger (P = 0.034), had lower NP VL (median 5.6 × 103 vs. 3.9 × 107, P < 0.001), and could not drool saliva at the end of the sampling (P = 0.002). VLs were lower with saliva than with NP RT-PCR (median 8.7 cp/mL × 104; interquartile range 1.2 × 104-5.2 × 105; vs. median 4.0 × 107 cp/mL; interquartile range, 8.6 × 105-1 × 108; P < 0.001).

CONCLUSIONS

While RT-PCR testing on saliva performed more poorly in younger children and likely after longer duration of symptoms, saliva remains an attractive alternative to NP swabs in children.

Adding saliva testing to oropharyngeal and deep nasal swab testing increases PCR detection of SARS-CoV-2 in primary care and children

Objective

To compare the concordance and acceptability of saliva testing with standard‐of‐care oropharyngeal and bilateral deep nasal swab testing for severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) in children and in general practice.

Design

Prospective multicentre diagnostic validation study.

Setting

Royal Children’s Hospital, and two general practices (cohealth, West Melbourne; Cirqit Health, Altona North) in Melbourne, July–October 2020.

Participants

1050 people who provided paired saliva and oropharyngeal‐nasal swabs for SARS‐CoV‐2 testing.

Main outcome measures

Numbers of cases in which SARS‐CoV‐2 was detected in either specimen type by real‐time polymerase chain reaction; concordance of results for paired specimens; positive percent agreement (PPA) for virus detection, by specimen type.

Results

SARS‐CoV‐2 was detected in 54 of 1050 people with assessable specimens (5%), including 19 cases (35%) in which both specimens were positive. The overall PPA was 72% (95% CI, 58–84%) for saliva and 63% (95% CI, 49–76%) for oropharyngeal‐nasal swabs. For the 35 positive specimens from people aged 10 years or more, PPA was 86% (95% CI, 70–95%) for saliva and 63% (95% CI, 45–79%) for oropharyngeal‐nasal swabs. Adding saliva testing to standard‐of‐care oropharyngeal‐nasal swab testing increased overall case detection by 59% (95% CI, 29–95%). Providing saliva was preferred to an oropharyngeal‐nasal swab by most participants (75%), including 141 of 153 children under 10 years of age (92%).

Conclusion

In children over 10 years of age and adults, saliva testing alone may be suitable for SARS‐CoV‐2 detection, while for children under 10, saliva testing may be suitable as an adjunct to oropharyngeal‐nasal swab testing for increasing case detection.

Portable RT-PCR System: a Rapid and Scalable Diagnostic Tool for COVID-19 Testing

Combating the ongoing coronavirus disease 2019 (COVID-19) pandemic demands accurate, rapid, and point-of-care testing with fast results to triage cases for isolation and treatment. The current testing relies on reverse transcriptase PCR (RT-PCR), which is routinely performed in well-equipped laboratories by trained professionals at specific locations.

Combating the ongoing coronavirus disease 2019 (COVID-19) pandemic demands accurate, rapid, and point-of-care testing with fast results to triage cases for isolation and treatment. The current testing relies on reverse transcriptase PCR (RT-PCR), which is routinely performed in well-equipped laboratories by trained professionals at specific locations. However, during busy periods, high numbers of samples queued for testing can delay the test results, impacting efforts to reduce the infection risk. Besides, the absence of well-established laboratories at remote sites and low-resourced environments can contribute to a silent spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). These reasons compel the need to accommodate point-of-care testing for COVID-19 that meets the ASSURED criteria (affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free, and deliverable). This study assessed the agreement and accuracy of the portable Biomeme SARS-CoV-2 system against the gold standard tests. Nasopharyngeal and nasal swabs were used. Of the 192 samples tested using the Biomeme SARS-CoV-2 system, the results from 189 samples (98.4%) were in agreement with the reference standard-of-care RT-PCR testing for SARS-CoV-2. The portable system generated simultaneous results for nine samples in 80 min with high positive and negative percent agreements of 99.0% and 97.8%, respectively. We performed separate testing in a sealed glove box, offering complete biosafety containment. Thus, the Biomeme SARS-CoV-2 system can help decentralize COVID-19 testing and offer rapid test results for patients in remote and low-resourced settings.

Saliva for molecular detection of SARS-CoV-2 in school-age children

Objectives

The high diagnostic accuracy indices for saliva severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcriptase PCR (RT-PCR) reported in adults has not been demonstrated in children, and adequately powered studies focused on the paediatric population are lacking. This study was carried out to determine the diagnostic accuracy of saliva for SARS-CoV-2 RT-PCR in ambulatory children.

Methods

During 1 to 23 October 2020, we recruited a population-based sample of children presenting for coronavirus disease 2019 (COVID-19) screening in Dubai, United Arab Emirates. Each child provided paired nasopharyngeal (NP) swab and saliva for SARS-CoV-2 RT-PCR N, E and RdRp gene detection.

Results

Paired NP swab and saliva samples were obtained from 476 children with mean ± standard deviation age of 10.8 ± 3.9 years, and 58.2% were male (277/476). Nine participants were sampled twice, so 485 pairs of NP swab/saliva were tested. Virus detection in at least one specimen type was reported in 17.9% (87/485), with similar detection in NP swab (16.7%, 81/485) and saliva (15.9%, 77/485). Sensitivity and specificity of saliva RT-PCR was 87.7% (95% confidence interval (CI) 78.5–93.9) and 98.5% (95% CI 96.8–99.5). The positive and negative predictive values were 92.2% (95% CI 84.2–96.3) and 97.6% (95% CI 95.7–98.6), with a kappa coefficient of 0.879 (95% CI 0.821–0.937). Concordance of findings between NP swab and saliva did not differ by age (p 0.67) or gender (p 0.29). Cycle threshold (Ct) values were significantly higher in NP swab/saliva pairs with discordant findings compared to those with both specimens positive.

Conclusions

In light of these findings, we recommend saliva as a diagnostic specimen for COVID-19 screening in children.