Sensitivity of Reverse Transcription Polymerase Chain Reaction Tests for Severe Acute Respiratory Syndrome Coronavirus 2 through Time

Abstract

Background. Reverse transcription polymerase chain reaction (RT-PCR) tests are the gold standard for detecting recent infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Reverse transcription PCR sensitivity varies over the course of an individual’s infection, related to changes in viral load. Differences in testing methods, and individual-level variables such as age, may also affect sensitivity. Methods. Using data from New Zealand, we estimate the time-varying sensitivity of SARS-CoV-2 RT-PCR under varying temporal, biological, and demographic factors. Results. Sensitivity peaks 4–5 days postinfection at 92.7% (91.4%–94.0%) and remains over 88% between 5 and 14 days postinfection. After the peak, sensitivity declined more rapidly in vaccinated cases compared with unvaccinated, females compared with males, those aged under 40 compared with over 40s, and Pacific peoples compared with other ethnicities. Conclusions. Reverse transcription PCR remains a sensitive technique and has been an effective tool in New Zealand’s border and postborder measures to control coronavirus disease 2019. Our results inform model parameters and decisions concerning routine testing frequency.