The National Health Surveillance Agency (Anvisa) approved on Monday (22) a new rapid test for Covid-19, developed by the pharmaceutical company Roche. The serological examination measures the presence of antibodies against the coronavirus in blood samples from patients and can indicate whether the person has already been in contact with the infectious agent.
According to the manufacturer, if applied 14 days after the onset of symptoms, the test has 99.03% sensitivity and 98.65% specificity. The first rate describes the ability of the test to identify patients who are actually infected, among people with suspected disease. The second corresponds to the ability of the procedure to correctly point out negative results in healthy individuals. The product should arrive in Brazil in November.
Like other serological tests, Roche’s rapid test involves collecting blood from the patient’s finger and can yield results in periods of 10 to 15 minutes. The degree of specificity allows for greater precision in identifying the antibodies of the new coronavirus and avoiding the interference of antibodies related to other diseases.
“In the current pandemic situation, tests that detect antibody responses against SARS-CoV-2 will be essential to support the development of vaccines and also to understand the rate and spread of infection among populations and, if the evidence evidence, to determine whether a person has acquired immunity or not to the new coronavirus, ”he told Roche in a statement.
Rapid tests are important tools to control the spread of the pandemic, as they can assist in tracking contamination and identifying asymptomatic patients. The tests, however, are not suitable for diagnosis in the early stages of Covid-19.
This is because the tests analyze two immunoglobulins: the IgM antibody can be produced by the immune system after a few days of the appearance of the first symptoms, while the IgG has a later response. If an analysis points to the absence of IgM and IgG, for example, there is a possibility that the patient has not been exposed to the coronavirus, but there are also chances that the individual has been infected and has not yet developed an immune response.
The most recommended test for early diagnosis is RT-PCR, which involves molecular analysis of airway samples from patients. The materials are collected by a swab, a kind of longer swab, inserted into the patient’s mouth or nostril.
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