Insight into the practical performance of RT-PCR testing for SARS-CoV-2 using serological data: a cohort study

Area of Science:

• Infectious Diseases
• Epidemiology
• Public Health

Background:

• Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RT-PCR testing has limitations for effective surveillance.
• Serological tests offer a complementary approach to virological detection.
• Assessing RT-PCR performance and identifying undetected SARS-CoV-2 infections is critical.

Purpose of the Study:

• To evaluate the performance of RT-PCR-based surveillance protocols for SARS-CoV-2.
• To determine the prevalence of SARS-CoV-2 infections missed by RT-PCR in Shenzhen, China.
• To assess the utility of serological testing in conjunction with RT-PCR.

Main Methods:

• A cohort study involving RT-PCR-negative close contacts of confirmed SARS-CoV-2 cases in Shenzhen, China.
• Measurement of anti-SARS-CoV-2 antibodies (total, IgG, IgM) using ELISA 2-15 weeks post-exposure.
• Serosurvey of volunteers from areas with and without reported cases.

Main Results:

• 4.1% of RT-PCR-negative close contacts were seropositive for SARS-CoV-2 antibodies.
• RT-PCR failed to detect 36% of infected close contacts, with false-negative rates linked to infection stage.
• Seropositive individuals were less likely to report symptoms than RT-PCR-positive individuals.

Conclusions:

• Rigorous RT-PCR protocols may miss a significant proportion of SARS-CoV-2 infections.
• Timing of RT-PCR testing, especially in asymptomatic individuals, impacts sensitivity.
• Despite limitations, comprehensive surveillance including RT-PCR and quarantine contained community spread in Shenzhen.