A National Institutes of Health (NIH) study has found that the effectiveness of rapid antigen tests is on par with laboratory-based polymerase chain reaction (PCR) tests for Covid-19 serial screening when used every three days.
The researchers affiliated with the NIH’s Rapid Acceleration of Diagnostics (RADx) programme noted that both testing approaches are equally efficient in identifying the SARS-CoV-2 virus.
The findings are from 43 individuals infected with Covid-19.
For the study, the team evaluated three viral testing modalities – PCR testing of saliva, PCR testing of nasal specimens and rapid antigen testing of nasal samples.
The saliva sample analysis was carried out using the University of Illinois at Urbana-Champaign (UIUC)’s covidSHIELD, an authorised saliva-based PCR test that delivers results in approximately 12 hours.
Abbott’s Alinity device was the PCR test used for nasal swab testing.
Quidel’s Sofia SARS Antigen Fluorescent Immunoassay device, which delivers results after 15 minutes, was used for rapid antigen testing in the study.
As compared to antigen tests, individual PCR tests are more sensitive, especially during the early stages of infection.
However, the study results demonstrated that both modes of testing had a sensitivity of 98% when performed regularly under a screening programme.
As antigen tests can offer quick results in point-of-care or at-home settings and are cheaper than lab tests, the latest findings indicate that rapid tests could be an effective screening tool to curb the Covid-19 outbreak.
The PCR molecular tests and rapid antigen tests showed increased sensitivity when viral cultures were positive for SARS-CoV-2.
NIH unit National Institute of Biomedical Imaging and Bioengineering (NIBIB) director Bruce Tromberg said: “Rapid antigen testing at home, two to three times per week, is a powerful and convenient way for individuals to screen for Covid-19 infection.
“With schools and businesses reopening, an individual’s risk of infection can change from day to day. Serial antigen testing can help people manage this risk and quickly take action to prevent spread of the virus.”
Furthermore, wider testing with antigen tests is expected to allow large-scale screening to identify asymptomatic transmitters.