Mid-June, millions of Spaniards are organizing, meditating and thinking about where they are going to spend your vacation this summer 2021. This year, everything indicates that we will live in a slightly more normalized way thanks to the vaccination campaign, we will finally be able to choose stay in Spain or leave our country to enjoy abroad again.
Whatever option it is, it is important to know that we must travel with the maximum guarantees to avoid incidents, and, suddenly, be confined by a contagion of Covid-19 or arriving at the airport and not having the proper credentials to be able to fly to the receiving country.
In this sense, and to be 100% prepared for the summer, it is very important to know in detail the Covid testing options. We spoke with Chiron prevention, the company for the prevention of occupational risks of the Quirónsalud Group that during the pandemic has carried out more than one million tests, to explain the characteristics of the different tests that exist and know which is the most appropriate when making our final choice.
The reference technique for the diagnosis of Covid-19 is RT-PCR due to its sensitivity in the early stages of contagion, since it can detect very low amounts of virus.
However, on the other hand, it does not differentiate by itself the stage of the disease in which the patient may find himself: onset, acute phase or recovery phase. If a negative result is obtained from a patient with a high suspicion of virus infection, it should be confirmed with a new test within a few days. The most common sampling is from the nasopharynx.
Another of the available options that this test allows is that the sample is taken in saliva. Is about an equally highly sensitive test of choice for the diagnosis of active infection (PDIA).
How do you explain us Juan Pedro Portell, director of the Occupational Health Area of Chiron prevention, the great advantage of this test is the comfort of taking the sample, since it can be done at any center and even at home, thanks to a kit that can be purchased online and includes all the elements and instructions for taking the sample and sending it to the laboratory .
RAPID ANTIGENS TEST
Also available is rapid antigen test, also cataloged as PDIA that detects the presence of the virus especially in the first 5 days from the beginning of the contagion with a high reliability of the result. The sampling is nasopharyngeal, as is the PCR.
«The main advantage is how quickly the result is obtained on site (15min), therefore without the need to send the test to the laboratory », concludes Portell.
Faced with a negative result and clinical suspicion of a disease that can be labeled as Covid-19, it is recommended, among other measures, to perform a conventional PCR after a couple of days.
TESTS FOR THE DETERMINATION OF IMMUNITY
It is based on the quantitative detection of specific IgG antibodies against Covid-19 in those people who have either overcome the infection symptomatically or asymptomatically with suspicion of having been exposed to the virus (close contact).
In this case, the sample is taken through a conventional blood extraction and it is not necessary to go on an empty stomach. The result will be available within 24-48 hours.
As a rule, antibodies are detected from 12-15 days since the beginning of the contagion, although it has been shown that a low percentage of the affected population does not generate antibodies after exposure. In the opinion of the specialist »It is possible to have overcome COVID-19 without developing antibodies. A small percentage of patients (around 2-5%) do not develop humoral immunity ”.
RAPID TEST OF ANTIBODIES
Although currently this test has greatly decreased its demand as it is a qualitative test, it was widely used at the beginning of the pandemic due to the limited availability of the previously mentioned tests.
It has a lower sensitivity and specificity compared to intravenous serology, but it has the advantage of the speed of the result and its non-referral to the laboratory.
In this sense, the specialist explains, “the required sample only requires a drop of blood obtained by fingerstick (finger). The result of it is available in less than 15 minutes ”.
POST VACCINATION SEROLOGY
Vaccines against Covid-19, as occurs in people who have suffered from the disease, allow for humoral immunity.
The most common vaccines have a mechanism of action that inhibits the binding of the virus to cells. The scientific evidence available allows us to affirm that approximately three weeks after the last dose of the vaccine dispensed, it can be detected, by performing this quantitative antibody test, its effectiveness by analyzing whether said antibodies have been generated against the virus. “However, the percentage of people who after vaccination develop antibodies against COVID-19 depends on the characteristics of each vaccine and the idiosyncrasy of each individual,” says the specialist from Chironprevention.
As has been commented in the case of post-disease immunity, it is possible to find a low percentage of patients who do not develop antibodies after having been vaccinated.
In this case, sampling also requires a conventional blood draw and does not require fasting.