Current Status of Laboratory Diagnosis for COVID-19: A Narrative Review

Figures & data

Table 1 Characteristics of Different Direct Tests for SARS-CoV-2

SARS-CoV-2 Test	Identification	Specimen	Specific Infrastructural Requirement	Optimal Timing for Testing (Days)	Turnaround Time (minutes)	Se (%)	Sp (%)
rt-PCR	RNA	nasopharyngeal and/or oropharyngeal swabs and/or lower respiratory specimen	Yes	At least 2 days after infection until negativization	190	≃89*	99**
RT-LAMP	RNA	nasopharyngeal and/or oropharyngeal swabs and/or lower respiratory specimen	Yes	At least 2 days after infection until negativization	45–60	comparable to rt-PCR	comparable to rt-PCR
NP antigen detection test	Antigen (Ag) of SARS-CoV-2	nasopharyngeal and/or oropharyngeal swabs and/or lower respiratory specimen	Yes	At least 2 days after infection until negativization	240	70–86**	95–97**

Abbreviations: rt-PCR, real time-protein chain reaction; RT-LAMP, reverse-transcription-loop-mediated isothermal amplification; NP, nucleoprotein; Se, sensitivity; Sp, specificity. * Data from meta-analysis; ** Data declared by producer.

Table 2 Advantages, Disadvantages, and Possible Indications of Different Direct Tests for SARS-CoV-2

SARS-CoV-2 Test C	Advantages	Disadvantages	Indications
rt-PCR	Widely used High sensitivity and specificity	Needs for infrastructure Expensive Medium turnaround time Qualified personnel Incorrect sampling Restrictions on sample transportation	Currently the gold standard in symptomatic and asymptomatic patients
RT-LAMP	Lowest turnaround time considering direct methods High sensitivity Less bias in the analytical phase	Needs for infrastructure Expensive Qualified personnel Incorrect sampling Restrictions on sample transportation	Substitute for rt-PCR where possible in order to reduce the turnaround time
NP antigen detection test	Easier analytical procedures Possible even in less equipped labs	No real-life studies Low sensibility Qualified personnel Incorrect sampling Restrictions on sample transportation	It could be used in facilities with no equipment for rt-PCR, waiting for the rt-PCR test

Abbreviations: rt-PCR, real-time protein chain reaction; RT-LAMP, reverse-transcription-loop-mediated isothermal amplification; NP, nucleoprotein.

Table 3 Characteristics of Different Indirect Test for SARS-CoV-2

SARS-CoV-2 Test	Type	Specimen	Specific Infrastructural Requirement	Optimal Timing for Testing (days)	Turnaround Time (minutes)	Se (%)	Sp (%)
ELISA	IgG and IgM	human serum, plasma, whole blood	Yes	After 17–19 days from infection	240	≃82*	≃97*
CLIA	IgM and IgG	human serum, plasma, whole blood	Yes	After 17–19 days from infection	30	≃77.9^§	≃100^§
Rapid detection test	IgG and IgM	fingerprick samples	No	After 17–19 days from infection	10–30	≃88.6^§	≃90.63^§

Abbreviations: ELISA, enzyme-linked immunosorbent assay; CLIA, chemiluminescence immunoassay; Se, sensitivity; Sp, specificity. * Data from meta-analysis; § Data from small cohort.

Table 4 Advantages, Disadvantages, and Possible Indications of Different Indirect Tests for SARS-CoV-2

SARS-CoV-2 Test	Advantages	Disadvantages	Indications
ELISA	Not very expensive Medium turnaround time Data confirmed by meta-analysis and cohort data Easy collection sampling Widely used technique	Needs infrastructure Qualified personnel	Population screening and/or second level test in order to confirm Rapid detection test results
CLIA	High throughput and sensitivity method Assist early detection of suspicious cases with nucleic acid false negative High production capacity with advanced automatic production line	Needs infrastructure Qualified personnel Data from small cohort	Population screening and/or second level test in order to confirm Rapid detection test results
Rapid detection test	Does not need infrastructure Easy collection sampling	Low specificity and sensitivity Data from small cohort data	Weekly screening in high risk population, eg, healthcare personnel

Abbreviations: ELISA, enzyme-linked immunosorbent assay; CLIA, chemiluminescence immunoassay.