Later than expected, but the rapid antigen tests, the result of which is obtained after 15 or 20 minutes (compared to the 24 or 48 hours it takes for PCR), are already working in Catalonia. This week they have finally been distributed in the 80% of primary care centers (CAP), 161 of which (in Catalonia there are more than 400 health centers) have already carried out 1,641 of these rapid tests. 80% of them have tested positive. At the same time, in recent days Catalonia has been carrying out some 30,000 PCR daily.
As explained this Wednesday the ‘councilor’ of Salut, Alba Vergés, rapid diagnostic antigen tests are only valid in people who present symptoms for the first five days. They are not useful in patients without symptoms, such as CRPs. “These tests are a complement to the current PCR,” explained Vergés, who clarified that Catalonia already has one million antigen tests, expandable to two million, of which have already been distributed 500.000.
The covid-19 pandemic is advancing without brake in a Catalonia that is considering, as Vergés has admitted, establishing a curfew in the coming days. In the last week, the Catalan CAPs have attended to 28,000 people suspected of having the virus. A week ago, there were 22,000 and a month ago, 13,000, which shows a “very clear growth of people with symptoms.”
According to the head of the Servei de Microbiologia del Vall d’Hebron Hospital (Barcelona), Tomás Pumarola, currently the two main diagnostic tools for covid-19 are PCR and antigen tests. “The difference is in the sensitivity, in the capacity they have to detect positive cases,” he said. PCRs remain the most reliable test; however, antigen tests have a sensitivity of 93% and a specificity of 90% during the first five days that people express symptoms.
Antigen tests, such as PCR, consist of a nasopharyngeal sample, but the result is obtained very quickly, after 15 or 20 minutes. In addition, there is another “diagnostic typology”: detection of antibodies, which is a blood test (serological) that detects the body’s response to the virus. To all this is added a new technology for PCR, the ‘pooling’, which allows analysis of more samples in less time. Even so, this technology should be used in areas of low prevalence, where the positives do not exceed 3%, such as ‘clean’ residences for the virus or in screening for health professionals.
On the fact that in some CAPs, such as the Roger de Flor from Barcelona, the flu campaign Due to “lack of stocks” of the vaccine, Vergés has called for calm and has guaranteed that the campaign will last two months and it will reach the whole world. “The campaign is going very well, but let us not be alarmed if at some point, due to the high demand, people are summoned within a week or two. We have two months to get vaccinated and this year more vaccines have been bought. They will reach the whole world “, it is finished.