Improving Detection Efficiency of SARS-CoV-2 Nucleic Acid Testing

Area of Science:

• Virology
• Infectious Diseases
• Diagnostic Testing

Background:

• Nucleic acid testing (NAT) is crucial for diagnosing SARS-CoV-2, the virus causing COVID-19.
• Concerns exist regarding the high false-negative rate of SARS-CoV-2 NAT.
• This study investigates the detection efficiency of SARS-CoV-2 NAT in a large COVID-19 patient cohort.

Purpose of the Study:

• To analyze the factors influencing SARS-CoV-2 NAT positive rates.
• To determine the optimal conditions for improving COVID-19 diagnostic accuracy using NAT.

Main Methods:

• Analysis of 4,275 specimens from 532 COVID-19 patients in Sichuan Province.
• Evaluation of NAT positive rates based on disease severity, status, stage, specimen type, and number of specimens.
• Correlation of detection rates with days relative to symptom onset.

Main Results:

• Overall SARS-CoV-2 NAT positive rate was 37.5%.
• Bronchoalveolar lavage fluid (BALF) showed the highest positive rate (77.8%), followed by upper respiratory tract (URT) specimens (38.5%).
• Detection rates were highest for critical cases (43.4%), during the early phase of illness (85-95% within 3 days of onset), and improved significantly with multiple consecutive respiratory specimen tests (up to 93.2%).

Conclusions:

• SARS-CoV-2 NAT detection efficiency is significantly influenced by disease severity, patient status, specimen type, and disease progression.
• Collecting multiple respiratory specimens consecutively and sampling close to symptom onset are key strategies to enhance diagnostic accuracy.
• Optimizing specimen collection protocols can mitigate the false-negative rate of SARS-CoV-2 NAT.