RIO DE JANEIRO, BRAZIL – Demand is high because of the end-of-year parties, but experts say that tests do not guarantee immunity. A private laboratory in São Paulo’s capital reports a 70% increase in demand for tests between December 1st and 22nd.
Demand for RT-PCR type Covid-19 tests in Brazil’s private network has increased 35% over the month, according to the Brazilian Association of Diagnostic Medicine (ABRAMED). According to specialists, demand is high because of the rise in cases and end-of-year parties, but they say that tests do not guarantee immunity and negative results can convey a false sense of safety.
The increase is related to the number of tests performed between November 25th and December 25th. ABRAMED represents laboratories that process approximately 60% of the diagnostic tests performed in the private network in Brazil.
According to Wilson Shcolnik, pathologist and the association’s chairman, since the start of the pandemic over seven million tests have been performed.
In São Paulo capital, in the CDB laboratory, demand for tests grew by 70% between December 1st and 22nd, compared to the same period in November.
By Saturday, December 26th, the state of São Paulo had registered 45,808 deaths and 1,423,340 confirmed cases. The daily case average stands at 5.6 thousand – one thousand more than the average in late November, according to the state government.
Experts alert to cases where results may be negative despite a person being infected.
“In asymptomatic patients, there may not be enough viral particles to the point of testing positive. In these cases, we may get false negative results, which can result in a false reassurance for end-of-year gatherings and flights,” said the pathologist.
In addition to private laboratories, some pharmacies provide the saliva test, the PCR-Lamp, which is more affordable than the PCR performed with nasal and throat secretions. For Luciano Brito, geneticist and researcher at USP (University of São Paulo), in terms of methodology both tests are reliable, but there are caveats to be made about the Lamp.
“It is possible that at certain stages of infection, the saliva will contain a lower viral load than the pharyngeal area,” Brito said.
The RT-PCR test is recommended after the fourth day of symptoms and detects if a person is infected at the time of testing.