The Costa Rican Social Security Fund (CCSS) implemented the mixed use of molecular and antigen tests – also known as rapid tests – for the diagnosis of COVID-19. This implementation has taken place gradually since December, and is already applied in 38 health establishments throughout the country.
“The PCR test is the key to the diagnostic process in the Pandemic; however, the antigen is used to give speed of diagnosis to people with symptoms of COVID-19 in the first days of evolution,” said Angie Cervantes, microbiologist and advisor to the Health Services Development Directorate.
Rapid tests have use restrictions to increase the certainty of diagnosis, for example, they should be applied in people with symptoms between day one and five of discomfort. In addition, it is recommended to analyze them within four hours after the sample is taken.
Low accuracy
According to the CCSS, if an asymptomatic person undergoes this test, he will have little chance that his result will be valid, since its detection capacity is lower when there are few viruses in respiratory secretions. Similarly, he reported that any negative test of this type must be confirmed with a PCR test.
The use of these tests, according to the institution, has gained more value in communities without a sophisticated laboratory for the confirmation of PCR tests, and for this reason, their mixed implementation allows a reduction in response time. It is estimated that in the coming months the coverage of antigen processing will be expanded to 80 laboratories.
