The director-general of Health said today that the objective of the authorities is to “quickly identify and isolate” the contacts of a person with covid-19, even if they are not tested.
“Our goal is this: to quickly isolate contacts, regardless of whether to do a test right away. It is immediate to proceed to isolation, with or without a test ”, noted Graça Freitas, at the regular press conference on the pandemic in Portugal, answering a question about a Lancet study, released on Thursday, which warns of the need to perform tests within the first 24 hours to prevent the spread of viruses.
The director-general warned that people placed in prophylactic isolation due to contact with infected people, if they test negative, “cannot freely interpret the test and leave home without authorization” from health authorities.
“If they test negative, they cannot come out on the street. They have to remain in isolation for 14 days ”, he warned.
There are currently 206 active covid-19 outbreaks in the country and the Minister of Health, Marta Temido, observed that “an outbreak is only considered closed” after “two incubation periods, that is, 28 days, from the infection of the last registered case”.
A scientific study published in the Lancet magazine indicates that, however effective the screening of contacts of people sick with covid-19, it will be of little use to stop the spread of the disease if diagnostic tests are not rapid.
“If the diagnostic test on covid-19 takes three or more days after a person develops symptoms, even the most effective contact screening strategy will not be able to reduce the transmission of the virus,” say the researchers responsible for the research released Thursday. market.
If test results are achieved within 24 hours with screening of at least 80% of contacts, the average number of contacts infected by a person (known as RT) can be reduced from 1.2 to 0.8, avoiding 80% transmissions of the new coronavirus, he adds.
“This study reinforces the conclusions of others, showing that contact screening can be an effective intervention to prevent the spread of the SARS-CoV-2 virus, but only with a high proportion of contacts and a quick testing process,” said one of the main authors of the study, Miriam Kretzschmar, from the Dutch university of Utrecht.
One of the main conclusions is that “mobile applications can make it possible to find people who are potentially infected faster, but if the tests take three days or more, even this technology will not be able to stop the transmission of the virus,” he said.
In tracking contacts, it is necessary to find all people who have been in contact with an infected person in order to be able to be isolated and thus prevent further contagion.
For the screening to be effective, it is necessary that the virus transmission rate translated into R0 is less than 01, that is, that the number of new infections caused by each person is less than one.
In the study, the mathematical model used assumes that about 40 percent of virus transmission occurs before an infected person shows symptoms of covid-19.
Therefore, contact tracking only works and can only keep the R below 01 if people with covid-19 receive a positive diagnosis on the day they are tested, as soon as they develop symptoms.
With no contagion mitigation measures, each person will infect an average of 2.5 people. However, only with physical distance, which reduces close contacts by 40% and casual contacts by 70%, the number of people infected by each patient becomes 1.2.
Today Portugal registers three more deaths and 312 new cases of infection by covid-19, compared to Thursday, 236 of which in the region of Lisbon and Vale do Tejo, according to the daily bulletin of the Directorate-General for Health (DGS).
According to the bulletin, since the beginning of the pandemic until today, there have been 48,077 confirmed cases of infection and 1,682 deaths.
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