At the gates of Christmas, the accumulated incidence of the coronavirus in Spain continues to skyrocket and is already at 441 cases per 100,000 inhabitants, an escalation of cases that is becoming visible every day.Given the imminent arrival of the summer dates and the increase in positives in covid-19, many have opted for the purchase of self-diagnostic antigen tests in pharmacies, of which there is already a lack of supply after their sales in the last month have increased by 545% according to the consulting firm IQVIA.Only in the week from November 29 to December 6, Spanish pharmacies sold 1,118,539 tests.But do you know what to do if you test positive?Unlike last year, at this time the vast majority of the population is vaccinated with the complete schedule, many over 60 years of age already have their third dose and children between 5 and 11 years of age have begun to receive the serum.However, the escalation of cases and the transmission of the omicron variant has made it advisable to carry out one of these tests before Christmas dinners and that their sale has skyrocketed in the population that has been in contact with a positive.The Spanish Agency for Medicines and Health Products (AEMPS) establishes that the sale of antigen tests for self-diagnosis is exclusively for sale in pharmacies, so they remember that they should not be purchased by other means and that the CE certificate must always be indicated.However, they point out that this test is not considered for the confirmation diagnosis of an active infection, but that if it tests positive, it will be considered a suspected case.According to the AEMPS, for the test to be more effective, it must be done in the first seven days after infection or in the first five days with symptoms related to covid-19 because these are the times when the viral load is higher and it is easier to detect the virus.The European Union advises the use of tests that have at least 97% specificity and a sensitivity of 90%.👉If you are going to use a self-diagnostic antigen test for #COVID19, you should take into account a series of recommendations.🦠 🧵[THREAD]👇 pic.twitter.com/jJ8gf5FZT1To take the test at home, follow the manufacturer's instructions.In general, you have to insert the swab into one or both nostrils without manipulating the part that goes into the nose with your hands.The instructions will include recommendations on how many centimeters the swab should be inserted inward, how many times it should be rotated in the nasal cavity, or how many seconds it should be inside to achieve the most accurate result possible.After that, the swab must be placed inside the extraction tube on which the reagent liquid has previously been poured.Once the swab is inserted, check that it fits snugly at the bottom of the tube.Once all the steps indicated by the manufacturer have been followed, a few drops should be poured on the card and the only thing left to do is wait 15 or 20 minutes for the result.As highlighted by the AEMPS, regardless of the result obtained, the control line C must always be clearly visible, which if only that appears means that the result is negative, while if the test line T is also displayed, it means that the test is positive."If when performing the test no colored line appears, or only the T line is displayed, but not the C line, the test is invalid and you must repeat it," they point out.In the event that the result is positive, either with or without symptoms, self-isolation should begin and contact your health center to expose the case.In addition, they remember that it is not a test that confirms active infection and must be confirmed with a diagnostic test, such as a PCR.However, if the result is negative, the AEMPS emphasizes that "it does not exclude the possibility of infection, it may be that the viral load is too low to be detected." For this reason, they advise continuing with the protection measures and, in case of having symptoms or being a close contact of a positive, they advise isolating themselves and contacting their health service to confirm the results with a more efficient test.