Key takeaway: Both types of RDTs are crucial for effective public health management.
Rapid diagnostic tests (RDTs) for COVID-19 can detect either antigen (Ag) or antibody (Ab), and both types of tests have important roles.
A combination is needed for effective patient management and public health planning.
This May 2020 report outlines general information on Ag- and Ab-detection RDTs for COVID-19, and suggested uses for them.
Polymerase chain reaction (PCR) or Ag
- Directly detects the virus and should be prioritized for diagnosis and monitoring
- Prioritize for case management to enable decentralized testing – particularly where PCR testing is limited.
Immune response tests or Ab
- Tests detecting viral immune response tests can be complementary for clinical care
- Should be prioritized for seroprevalence and epidemiological purposes
- Prioritize Ab RDTs for seroprevalence surveys to inform public health measures and testing of contacts to establish previous viral spread.
The value of any test is dependent on factors such as the test performance, or sensitivity/specificity, as well as the epidemiological context, or prevalence in the population where it is used, and timing.
The report also lists unique features of SARS-COV-2 to consider when using RDTs and specifies operational characteristics, such as how to interpret test results.