Comparative Performance of SARS-CoV-2 Detection Assays Using Seven Different Primer-Probe Sets and One Assay Kit

Laboratory Tests for COVID-19: A Review of Peer-Reviewed Publications and Implications for Clinical Use

Diagnostic tests for the coronavirus infection 2019 (COVID-19) are critical for prompt diagnosis, treatment and isolation to break the cycle of transmission. A positive real-time reverse-transcriptase polymerase chain reaction (RT-PCR), in conjunction with clinical and epidemiologic data, is the current standard for diagnosis, but several challenges still exist. Serological assays help to understand epidemiology better and to evaluate vaccine responses but they are unreliable for diagnosis in the acute phase of illness or assuming protective immunity. Serology is gaining attention, mainly because of convalescent plasma gaining importance as treatment for clinically worsening COVID-19 patients. We provide a narrative review of peer-reviewed research studies on RT-PCR, serology and antigen immune-assays for COVID-19, briefly describe their lab methods and discuss their limitations for clinical practice.

DIRECT RT-qPCR DETECTION OF SARS-CoV-2 RNA FROM PATIENT NASOPHARYNGEAL SWABS WITHOUT AN RNA EXTRACTION STEP

The ongoing COVID-19 pandemic has caused an unprecedented need for rapid diagnostic testing. The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) recommend a standard assay that includes an RNA extraction step from a nasopharyngeal (NP) swab followed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) to detect the purified SARS-CoV-2 RNA. The current global shortage of RNA extraction kits has caused a severe bottleneck to COVID-19 testing. We hypothesized that SARS-CoV-2 RNA could be detected from NP samples via a direct RT-qPCR assay that omits the RNA extraction step altogether, and tested this hypothesis on a series of blinded clinical samples. The direct RT-qPCR approach correctly identified 92% of NP samples (n = 155) demonstrated to be positive for SARS-CoV-2 RNA by traditional clinical diagnostic RT-qPCR that included an RNA extraction. Thus, direct RT-qPCR could be a front-line approach to identify the substantial majority of COVID-19 patients, reserving a repeat test with RNA extraction for those individuals with high suspicion of infection but an initial negative result. This strategy would drastically ease supply chokepoints of COVID-19 testing and should be applicable throughout the world.

COVID-19 Pandemic and Children: A Review

The severe respiratory disease COVID-19 (coronavirus disease 2019) was first reported in late December 2019 in Wuhan City, China. Soon thereafter, the World Health Organization (WHO) officially declared it a pandemic. The adult population is highly affected by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2); however, infants and children are also not spared. Transmission in the pediatric population appears to be primarily from COVID-19-positive adults, largely from family contacts through droplets, direct contacts, and aerosols. There is also evidence of fecal-oral route of transmission. The incubation period of COVID-19 in children ranges from 2 to 10 days. Most children are asymptomatic. The most common symptoms amongst symptomatic children are fever and cough. Shortness of breath, sore throat, rhinorrhea, conjunctivitis, fatigue, and headache are other common symptoms. Diarrhea, vomiting, and abdominal pain are the common gastrointestinal symptoms that may be present with or without respiratory symptoms. Very few children are likely to develop severe disease.Supportive care is the mainstay of treatment. Though data are limited, antiviral therapies such as remdesivir, favipiravir, lopinavir/ritonavir, and other drugs like hydroxychloroquine/chloroquine have been used for severe COVID-19 cases, with remdesivir showing the greatest promise. A few children may develop an exaggerated immune response, characterized by exaggerated cytokine release and manifests with features similar to Kawasaki disease. The syndrome has been referred to by many names including pediatric inflammatory multisystem syndrome (PIMS) and more recently, as multisystem inflammatory syndrome in children (MIS-C); this life-threatening condition often requires a multidisciplinary team effort and use of immunomodulators.