<h4>Background</h4>Comprehensive information about the accuracy of antigen rapid diagnostic tests (Ag-RDTs) for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is essential to guide public health decision makers in choosing the best tests and testing policies. In August 2021, we published a systematic review and meta-analysis about the accuracy of Ag-RDTs. We now update this work and analyze the factors influencing test sensitivity in further detail.<h4>Methods and findings</h4>We registered the review on PROSPERO (registration number: CRD42020225140). We systematically searched preprint and peer-reviewed databases for publications evaluating the accuracy of Ag-RDTs for SARS-CoV-2 until August 31, 2021. Descriptive analyses of all studies were performed, and when more than 4 studies were available, a random-effects meta-analysis was used to estimate pooled sensitivity and specificity with reverse transcription polymerase chain reaction (RT-PCR) testing as a reference. To evaluate factors influencing test sensitivity, we performed 3 different analyses using multivariable mixed-effects meta-regression models. We included 194 studies with 221,878 Ag-RDTs performed. Overall, the pooled estimates of Ag-RDT sensitivity and specificity were 72.0% (95% confidence interval [CI] 69.8 to 74.2) and 98.9% (95% CI 98.6 to 99.1). When manufacturer instructions were followed, sensitivity increased to 76.3% (95% CI 73.7 to 78.7). Sensitivity was markedly better on samples with lower RT-PCR cycle threshold (Ct) values (97.9% [95% CI 96.9 to 98.9] and 90.6% [95% CI 88.3 to 93.0] for Ct-values <20 and <25, compared to 54.4% [95% CI 47.3 to 61.5] and 18.7% [95% CI 13.9 to 23.4] for Ct-values ≥25 and ≥30) and was estimated to increase by 2.9 percentage points (95% CI 1.7 to 4.0) for every unit decrease in mean Ct-value when adjusting for testing procedure and patients' symptom status. Concordantly, we found the mean Ct-value to be lower for true positive (22.2 [95% CI 21.5 to 22.8]) compared to false negative (30.4 [95% CI 29.7 to 31.1]) results. Testing in the first week from symptom onset resulted in substantially higher sensitivity (81.9% [95% CI 77.7 to 85.5]) compared to testing after 1 week (51.8%, 95% CI 41.5 to 61.9). Similarly, sensitivity was higher in symptomatic (76.2% [95% CI 73.3 to 78.9]) compared to asymptomatic (56.8% [95% CI 50.9 to 62.4]) persons. However, both effects were mainly driven by the Ct-value of the sample. With regards to sample type, highest sensitivity was found for nasopharyngeal (NP) and combined NP/oropharyngeal samples (70.8% [95% CI 68.3 to 73.2]), as well as in anterior nasal/mid-turbinate samples (77.3% [95% CI 73.0 to 81.0]). Our analysis was limited by the included studies' heterogeneity in viral load assessment and sample origination.<h4>Conclusions</h4>Ag-RDTs detect most of the individuals infected with SARS-CoV-2, and almost all (>90%) when high viral loads are present. With viral load, as estimated by Ct-value, being the most influential factor on their sensitivity, they are especially useful to detect persons with high viral load who are most likely to transmit the virus. To further quantify the effects of other factors influencing test sensitivity, standardization of clinical accuracy studies and access to patient level Ct-values and duration of symptoms are needed.

<h4>Introduction</h4>Reverse transcription-polymerase chain reaction (RT-PCR) to detect SARS-CoV-2 is time-consuming and sometimes not feasible in developing nations. Rapid antigen test (RAT) could decrease the load of diagnosis. However, the efficacy of RAT is yet to be investigated comprehensively. Thus, the current systematic review and meta-analysis were conducted to evaluate the diagnostic accuracy of RAT against RT-PCR methods as the reference standard.<h4>Methods</h4>We searched the MEDLINE/Pubmed and Embase databases for the relevant records. The QUADAS-2 tool was used to assess the quality of the studies. Diagnostic accuracy measures [i.e., sensitivity, specificity, diagnostic odds ratio (DOR), positive likelihood ratios (PLR), negative likelihood ratios (NLR), and the area under the curve (AUC)] were pooled with a random-effects model. All statistical analyses were performed with Meta-DiSc (Version 1.4, Cochrane Colloquium, Barcelona, Spain).<h4>Results</h4>After reviewing retrieved records, we identified 60 studies that met the inclusion criteria. The pooled sensitivity and specificity of the rapid antigen tests against the reference test (the real-time PCR) were 69% (95% CI: 68-70) and 99% (95% CI: 99-99). The PLR, NLR, DOR and the AUC estimates were found to be 72 (95% CI: 44-119), 0.30 (95% CI: 0.26-0.36), 316 (95% CI: 167-590) and 97%, respectively.<h4>Conclusion</h4>The present study indicated that using RAT kits is primarily recommended for the early detection of patients suspected of having COVID-19, particularly in countries with limited resources and laboratory equipment. However, the negative RAT samples may need to be confirmed using molecular tests, mainly when the symptoms of COVID-19 are present.

<h4>Objective</h4>To systematically assess the diagnostic accuracy of rapid point-of-care tests for diagnosis of current SARS-CoV-2 infections in children under real-life conditions.<h4>Design</h4>Systematic review and meta-analysis.<h4>Data sources</h4>MEDLINE, Embase, Cochrane Database for Systematic Reviews, INAHTA HTA database, preprint servers (via Europe PMC), ClinicalTrials.gov, WHO ICTRP from 1 January 2020 to 7 May 2021; NICE Evidence Search, NICE Guidance, FIND Website from 1 January 2020 to 24 May 2021.<h4>Review methods</h4>Diagnostic cross-sectional or cohort studies were eligible for inclusion if they had paediatric study participants and compared rapid point-of care tests for diagnosing current SARS-CoV-2 infections with reverse transcription polymerase chain reaction (RT-PCR) as the reference standard. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool was used to assess the risk of bias and the applicability of the included studies. Bivariate meta-analyses with random effects were performed. Variability was assessed by subgroup analyses.<h4>Results</h4>17 studies with a total of 6355 paediatric study participants were included. All studies compared antigen tests against RT-PCR. Overall, studies evaluated eight antigen tests from six different brands. Only one study was at low risk of bias. The pooled overall diagnostic sensitivity and specificity in paediatric populations was 64.2% (95% CI 57.4% to 70.5%) and 99.1% (95% CI 98.2% to 99.5%), respectively. In symptomatic children, the pooled diagnostic sensitivity was 71.8% (95% CI 63.6% to 78.8%) and the pooled diagnostic specificity was 98.7% (95% CI 96.6% to 99.5%). The pooled diagnostic sensitivity in asymptomatic children was 56.2% (95% CI 47.6% to 64.4%) and the pooled diagnostic specificity was 98.6% (95% CI 97.3% to 99.3%).<h4>Conclusions</h4>The performance of current antigen tests in paediatric populations under real-life conditions varies broadly. Relevant data were only identified for very few antigen tests on the market, and the risk of bias was mostly unclear due to poor reporting. Additionally, the most common uses of these tests in children (eg, self-testing in schools or parents testing their toddlers before kindergarten) have not been addressed in clinical performance studies yet. The observed low diagnostic sensitivity may impact the planned purpose of the broad implementation of testing programmes.<h4>Prospero registration number</h4>CRD42021236313.

We assessed the performance of the Panbio rapid antigen detection (RAD) test for the detection of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection and we compared it with the routine reverse transcriptase‐polymerase chain reaction (RT‐PCR)‐based molecular test in a population of 4167 unselected patients admitted to IRCCS Sacro Cuore Don Calabria Hospital. Analysis stratified by cycling threshold (Ct) value of SARS‐CoV‐2 gene targets indicated that antigen (Ag)‐positive Ct values were significantly lower compared to Ag‐negative values (p < 0.0001). Overall, we found discordance in 140, tested negative by RAD and positive by RT‐PCR, and in 4 resulted positive by RAD and negative by RT‐PCR. RAD test achieved a sensitivity and specificity of 66.82% and 99.89%, respectively. The positive predictive value was shown to be 97.87% while the negative predictive value was shown to be 97.62%. In our context, the RAD test showed a reliable diagnostic response in subjects that displayed high Ct values, corresponding to high viral load, while low ability was displayed to identify positive cases with medium‐low Ct values, thus presenting low viral load and where confirmatory RT‐PCR was needed. Our finding supports the use of the RAD test in real‐life settings where a high volume of swabs is being processed but with caution when interpreting a positive test result in a low prevalence setting.

d extraction with the MagNA Pure System (Roche Diagnostics), in accordance with the manufacturer’s instructions. The presence of the E gene, RdRP gene, and N gene of the SARS-CoV-2 virus were identified by a commercial RT-PCR assay (Allplex 2019-nCoV Assay; Seegene). Samples were considered positive at molecular screening if all three genes were detected. The Centers for Disease Control and Prevention RT-PCR protocol was used to confirm the presence of SARS-CoV-2 [ 9 ]. To date [ 10 , 11 ], this methodology is considered the gold standard for the detection of SARS-CoV-2 infection. SARS-CoV-2 IgM/IgG Rapid Test The SARS-CoV-2 IgM/IgG combined antibody rapid test kit, VivaDiag, (VivaChek Biotech) is a lateral flow qualitative immunoassay used for the rapid determination of the presence or absence of both anti-SARS-CoV-2-IgM and anti-SARS-CoV-2-IgG in human specimens (whole blood, serum, and plasma). A surface antigen from SARS-CoV-2, which can specifically bind to SARS-CoV-2 antibodies (including both IgM and IgG), is conjugated to colloidal gold nanoparticles and sprayed onto conjugation pads. The rapid SARS-CoV-2 IgG/IgM combined antibody test strip has two mouse antihuman monoclonal antibodies (anti-IgG and anti-IgM) on two separate test lines. When testing, 10-15 µL of a specimen was inserted into the sample port, and then the sample dilution buffer was added. As the specimen flowed through the device, anti-SARS-CoV-2 IgG and IgM antibodies, if present in the specimen, were bound by the SARS-CoV-2 antigens (ie, the gold colorimetric reagent fixed on the conjugate pad). As the conjugated sample continued to travel up the strip, the anti-SARS-CoV-2 IgM antibodies were bound on the M (IgM) line, and the anti-COVID-19 IgG antibodies were bound to the G (IgG) line. If the specimen did not contain SARS-CoV-2 antibodies, no labeled complexes were bound. The presence of SARS-CoV-2 IgG and IgM antibodies was indicated by a red/purple line on a specific region of the device

Sufficient high-quality data are unavailable to describe the management approach and guideline of COVID-19 disease in pediatric and adolescent population which may be due to mild presentation in most of cases and less severe complications than older ages. World Health Organization was concerned with the establishment of an approved guideline to manage the increasing number of COVID-19 patients worldwide aiming to prevent or lessen COVID-19 global burden. The clinical features have a wide spectrum starting from uncomplicated mild illness, mild-moderate pneumonia, severe pneumonia, acute respiratory distress syndrome, sepsis, septic shock, and multisystem inflammatory syndrome in children. Many important definitions were developed to identify the COVID-19 case status including confirmed, suspected, and probable case. Many laboratory tests may be beneficially done but reverse transcriptase – polymerase chain reaction (RT-PCR) for SARS-CoV-2 RNA is diagnostic. Patient isolation and adequate intake of fluid and calories, antipyretics (preferably paracetamol), antibiotics (in secondary bacterial infections), and bed rest are the mainstay of approved supportive treatment. While oxygen supplementation may be added in moderate to severe cases; anticoagulation prophylaxis (enoxaparin) is strongly advised in children with certain situations where hypercoagulability state is identified, and therapy should be evaluated based on risk factors. New approaches, drugs, and therapies are curren

COVID-19 rapid antigen tests or RATs, also frequently called COVID-19 lateral flow tests or LFTs, are rapid antigen tests used to detect SARS-CoV-2 infection COVID-19 rapid antigen tests or RATs, also frequently called COVID-19 lateral flow tests or LFTs, are rapid antigen tests used to detect SARS-CoV-2 infection (COVID-19). They are quick to implement with minimal training, cost a fraction of other forms of COVID-19 testing, and give users a result within 5–30 minutes. RATs have been used in several countries as part of mass testing or population-wid COVID-19 rapid antigen tests or RATs, also frequently called COVID-19 lateral flow tests or LFTs, are rapid antigen tests used to detect SARS-CoV-2 infection (COVID-19). They are quick to implement with minimal training, cost a fraction of other forms of COVID-19 testing, and give users a result within 5–30 minutes. RATs have been used in several countries as part of mass testing or population-wide screening approaches. Many RATs can be used for self-testing, in which an individual "collects their own specimen… and interpret[s] their test result themselves". False positives are very rare; the tests' specificity is 98%-99%. However, the tests have a sensitivity of 70%-72%, which is lower than COVID-19 polymerase chain reaction (PCR) tests' sensitivity of 88%-96%. Despite this, COVID-19 RATs remain valuable in finding people who would otherwise not know they were infected, helping to prevent further transmission. The tests are more sensitive in the symptomatic and transmissive stages of disease when the viral load is higher.

COVID-19 testing involves analyzing samples to assess the current or past presence of SARS-CoV-2, the virus that causes COVID-19 and is responsible for the COVID-19 testing involves analyzing samples to assess the current or past presence of SARS-CoV-2, the virus that causes COVID-19 and is responsible for the COVID-19 pandemic. The two main types of tests detect either the presence of the virus or antibodies produced in response to infection. Molecular tests for viral presence through its molecular components are used to diagnose individual cases an An antigen is the part of a pathogen that elicits an immune response. Antigen tests look for antigen proteins from the viral surface. In the case of a coronavirus, these are usually proteins from the surface spikes. SARS-CoV-2 antigens can be detected before onset of COVID-19 symptoms (as soon as sufficient SARS-CoV-2 virus particles are present) with more rapid test results, but with less sensitivity than PCR tests for the virus. COVID-19 rapid antigen tests are lateral flow immunoassays that detect the presence of a specific viral antigen, which indicates current viral infection. Antigen tests produce results quickly (within approximately 15–30 minutes), and most can be used at the point-of-care or as self-tests. Self-tests are rapid tests that can be taken at home or anywhere, are easy to use, and produce rapid results. Antigen tests can be performed on nasopharyngeal, nasal swab, or saliva specimens. Antigen tests that can identify SARS-CoV-2 offer a faster and less expensive method to test for the virus. Antigen tests are generally less sensitive than real-time reverse transcription polymerase chain reaction (RT-PCR) and other nucleic… RT-P…