Diagnosis of COVID-19: Considerations, controversies and challenges

Area of Science:

• Virology
• Infectious Diseases
• Epidemiology

Background:

• The COVID-19 pandemic, caused by SARS-CoV-2, has led to millions of cases and deaths globally.
• Most symptomatic COVID-19 cases present with mild upper respiratory tract symptoms.
• Accurate and timely diagnosis is crucial for managing the pandemic.

Purpose of the Study:

• To evaluate the diagnostic utility of RT-PCR and antibody-based immunoassays for COVID-19.
• To understand the temporal dynamics of viral RNA detection and antibody responses.
• To explore the potential roles of different diagnostic methods in clinical management and public health.

Main Methods:

• Reverse transcription polymerase chain reaction (RT-PCR) on nasopharyngeal samples for viral RNA detection.
• Detection of IgM and IgG antibodies following symptom onset.
• Evaluation of antibody-based immunoassays for diagnostic and surveillance applications.

Main Results:

• RT-PCR has an approximate 30% false-negative rate early in disease or in mild cases, often necessitating repeat testing.
• Viral RNA detection by RT-PCR can persist post-symptom resolution.
• IgM and IgG antibody responses become detectable several days after symptom onset, with robust responses in the second week.
• Antibody-based immunoassays have limited utility in diagnosing early symptomatic disease but may be useful for surveillance.

Conclusions:

• RT-PCR remains the primary diagnostic method for COVID-19, despite potential for false negatives.
• Antibody testing is valuable for assessing past infection and immune status, aiding surveillance efforts.
• Ongoing research is clarifying the role of antibody tests in conjunction with RT-PCR for early diagnosis and other applications, such as vaccination assessment and workforce screening.