Fiocruz: RT-PCR test positivity rose from 3% to 37% in January

The Oswaldo Cruz Foundation (Fiocruz) announced today (1) that it has increased the number of positive covid-19 RT-PCR tests analyzed in its laboratories. In December 2021, for every 100 tests analyzed, 3 were positive. In January, as of the 24th, out of every 100 tests, 37 tested positive for SARS-CoV-2. Since the beginning of the epidemic, processing centers in Fiocruz have processed 35% of all RT-PCR samples collected at the Unified Health System (SUS).

Data for RT-PCR tests performed in the public network are standardized and analyzed by Fiocruz Laboratories and monitored by the Fiocruz Testing Bureau, based on sources such as the Department of Health Laboratory Environment Management System (GAL) and Central of Major Processing in Fiocruz, Rio de Janeiro, Ciara and Parana.

The survey shows that the three centers of the institution recorded an increase in the number of positive tests. The Rio de Janeiro-based Covid-19 Diagnostic Support Unit (Unadig-RJ), which processes samples from the same state, Rio Grande do Sul and Minas Gerais, left 2% of positive tests in December, when 52,000 RT-PCR tests were processed by 37% as of January 24, 2022 with 88 thousand samples analyzed.

In the unit based in Ceará, which analyzes samples from the same state, Santa Catarina and São Paulo, the proportion of tests with positive results rose from 4%, in a world of 13,000 tests, to 40%, in 58 thousand samples. In Parana, where only samples from the same state are processed, positivity rose from 4% to 35%, while the number of tests processed increased from 65,000 in December to 120,000 by January 24.

The number of tests performed was on a declining trajectory in December. In the first epidemiological week of the month, 41,000 tests were processed by Fiocruz, a number that has fallen to 22,000 in the past week. But during January, the number grew rapidly until it reached 121,000 only in the third epidemic week (January 16 to 22), which is a 195% increase compared to the average of the previous eight weeks.

Since the beginning of the epidemic, Vicruz centers have processed more than 9.5 million RT-PCR tests in support of the Ministry of Health, serving 23 units of the union. The RT-PCR test is the gold standard for SARS-CoV-2 detection and is also ideal for diagnosing asymptomatic people with a low viral load.

For Unadig’s general coordinator, Erika de Carvalho, the context of the year-end encounters and the easing of social isolation measures after vaccination progress helps explain the increase in cases. This made Micron expand and infect such a large number of people. We know infection is an easier strain and that explains the numbers well, the researcher told Agência Fiocruz de Notícias.