1. In what situations is a diagnostic test for the novel coronavirus determined?
In case of suspicion of disease, it is always recommended to carry out the test in accordance with the recommendations of the General Directorate of Health, the suspicion being based on the presentation of symptoms.
2. What distinguishes the different types of tests?
We have three types of tests in Portugal: molecular, rapid antigenic and serological tests.
Molecular testing is the gold standard for diagnosing and detecting the presence of the SARS-CoV-2 virus in a biological product extracted by swabs from the nose and throat. The results must be known between 12 and 24 hours because, before the analysis, it is necessary to replicate the collected material (RNA) several times.
Rapid antigenic tests identify the proteins of the virus, the biological material being collected by swabs, but the result is available in 20 to 30 minutes. This test has a precise indication, and should be used within the first five days of illness, in order to reduce false negatives. They can also be used for screening when molecular molecules are not available.
3. What are serological tests?
Serological tests assess whether a person has developed anti-Covid-19 antibodies from a drop of blood. If you have developed it is a sign that you have come in contact with the virus. However, they are not used for the diagnosis of Covid-19 because there is not enough scientific evidence on the importance of the presence of the different antibodies in the blood.
4. What is the sensitivity of each of these tests?
Rapid antigenic tests have a sensitivity greater than 90%. As for molecular tests, the sensitivity and specificity are greater than 99%.
5. Is contact with a positive case always a test criterion?
According to scientific evidence, contact with a positive is not always indicated for testing.
6. If there is such an indication, how long after contact should I wait to take the test?
After contact with an infected person, the incubation period can range from 2 to 14 days. Thus, in the early days, the likelihood of having developed the body’s response to the virus is unlikely. Perhaps between the 5th and 7th day, in most people the virus can already be detected.
7. If the result is negative, can I leave home and return to work or school?
Performing the test does not change the guidelines if the test is negative. As the incubation period can be up to 14 days, isolation should also last 14 days. Therefore, you cannot leave home or go to work until 14 days have passed after the last contact with the infected person.
8. When is it necessary to repeat a test?
After a positive test, there is no indication for a repeat test to determine cure. If the patient has three days without fever and with significant improvement in symptoms, he can be discharged, without examination, on the 10th day if the illness was mild to moderate, or after 20 days if the illness was severe or critical.
For you who visit us regularly, we have a special campaign.
RLDESC2020 – Use this code in
If you are already a subscriber, log in with your account. Login
9. Which entities can order diagnostic tests?
If illness is suspected, tests can be ordered by any doctor or through the SNS24 line.
10. What is the advantage of a company or institution testing the whole team?
Screening tests give a picture of workers before Covid on a given day, making it possible to isolate the sick from the non-sick. However, if there is no symptomatic person, the likelihood of positive results is low. However, given the existence of a positive person in a company, screening all workers can be very useful in breaking the chains of disease transmission.
Rapid tests are used for symptoms, only in the first five days of illness, to reduce false negatives. The molecular test is the benchmark for the diagnosis and screening of SARS-CoV-2 infection ”
Rui Passadouro, public health delegate at ACES Pinhal Litoral
11. I will have to travel. Do I have to take a test?
Many countries require negative entry tests. I recommend looking for these countries on the airline website i.e. TAP.
12. What are the advantages of serological tests?
Currently, they are not used for the diagnosis of Covid-19 because there is insufficient scientific evidence as to the importance of the presence of the different antibodies in the blood.
13. Who can or should take this test and under what circumstances?
There is no indication to perform it for diagnostic purposes.
14. Can I take this test on my own?
Yes, because they are available on the market. They can also be prescribed by doctors in very specific circumstances, especially if there is any doubt that the patient has been in contact with the virus before. However, they are not reimbursed by the SNS.
15. I had a serological test and proved that I was in contact with the virus and that I had developed antibodies. Does this mean that I am protected?
This is a very relevant question, but the answer is not easy because, at this time, it is not yet possible to correlate the values presented in the immunoassay with those that confer immunity, not even how many time this immunity will be maintained.
See more questions and answers on the following topics
(Article published in the December 10, 2020 edition of REGION OF LEIRIA)https://thetrustedchronicle.com/