Antigen test is reliable in the first three days of infection

Antigen tests have a diagnostic value to detect the Covid-19 virus, but in the face of changes in the omicron variant in viral load, their result is more reliable if performed in the first three days of the onset of clinical manifestations.

If the antigen test is done before or after this period, the sensitivity decreases, and therefore the results could be false negatives.

This is explained by the virologist from the Ibero-American University (UNIBE), Robert Paulino, who points out that it cannot be said in an absolute way that diagnostic tests are not helpful or predictive for diagnosis because it would be a mistake since they do have their value diagnosis. “The point is that in the scenario of an infection of the omicron variant, the virus has a difference in viral load, and the sensitivity is affected at the extremes of the illness. Therefore, he understands that for that reason, in these cases, when suspected by clinical manifestations that are highly suspicious of Covid-19, doctors recommend doing the PCR test subsequently. However, he recognizes that this has financial connotations because the antigen test must first be done, which costs between 1,700 and 2,000 pesos, and the PCR will cost between 4,700 and 5,000 pesos.