05/10/2020 - 18:53
- Clarín.com
- Society
Rapid coronavirus tests - which are used to detect people who have passed through the disease without being diagnosed - were at the center of the controversy, after their effectiveness was questioned in the last few hours. From the Government they assured that they fulfill the expected function: add details for an epidemiological investigation . In addition, they clarified that these tests for the detection of antibodies, which they brought from China and began to be carried out in Retiro, Constitución and Once, were donated.
Doubts about the sensitivity of the tests arose after 1,200 rapid tests were performed and only eight people tested positive . From the Ministry of Health they specified that before planning the study based on the donated tests "validation was requested from CONICET and the Ministry of Science and Technology."
"There in the return they told us that in IgM (immunoglobulin M) the sensitivity is low and they recommended not to use it and in IgG (immunoglobulin G) it has an average of 80% sensitivity and that they recommended to observe well specifically as it was weak to evaluate The positive. With that information, we designed the study we did. IgM was not used, and the personnel were trained to observe the strip regarding the weakness, "they added from the Health portfolio.
And they added, referring to the efficacy of the tests, that "worldwide it is known that no test has 100 percent sensitivity and specificity."
Along the same lines, the Minister of Science, Technology and Innovation, Roberto Salvarezza, published his opinion on Twitter: "The test strips (known as rapid tests) used by @msalnacion at the stations of Constitución, Retiro and Once are suitable for making epidemiological studies. They have a sensitivity of 80%, being one of the best we tested in the country to detect IgG. "
As explained to Clarín Lautaro de Vedia, former president of the Argentine Society of Infectious Diseases, there are two main types of antibodies that can be analyzed from rapid tests: IgMs, which are those that appear two or three days after manifesting the illness; and IgGs that develop later and last for many years or a lifetime.
He says he has no record of studies that measure IgM but that he does know of the existence of other quick tests that are slightly more sensitive in relation to IgG . "It is not ideal that two cases out of ten escape you. Sensitivity is a little low. However, it should not be forgotten that the objective of this study is not the detection of cases of current disease but to establish the level of viral circulation in the community, "says the infectologist at the Muñiz Hospital.
"We always knew that they were not used for diagnosis (that's what the swabs are for using the PCR technique) and that, in fact, they were for an epidemiological investigation. Furthermore, no rapid test has 100% sensitivity, " added sources from Casa Rosada. .
In total, the Health portfolio has 170,000 rapid tests by the Chinese firm Zhuhai Livzon Diagnostics. This is not the first controversy with these kits. The Indian Medical Research Council recently canceled a major purchase it had made on the grounds of "poor quality" and being "over priced" .
In the Argentine case, and when asked by this newspaper about the choice of these kits and not others or the use of the money that this acquisition implied for other purposes, the Government maintained that " the tests were donated and not money, and that this was the decision of the company that made them available in the context of the emergency. "
"Anmat did not pass the test to market, but it did for this particular study. What we are going to have is a photo of people who have positive antibodies in Argentina, knowing that if the sensitivity is 80%, there may be a 20 % more and we took this data into account. It is incorrect to say that the tests are defective, because to say that means to say that it does not fulfill what it promises and this is not so, "they concluded from the Ministry of Health.
What are they used for
These tests are part of the Covid-19 Surveillance Study operation for the evaluation of people with positive serology for the SARS-CoV-2 virus, which began last month, after receiving the donation from China.
Coronavirus testing in Retiro. (DPA)
On April 24, 400 tests were carried out at the Constitución station and all were negative ; on April 29 it was done among 431 people at the Retiro station, with a positive ; and the following day 420 were performed at the Once station, with seven positives .
The coronavirus health surveillance study is intended for volunteers, over 18 years of age, but without symptoms or who have had them in the last 20 days or more.