Between 30% and 40% of the Covid-19 polymerase chain reaction (PCR) tests performed in Russia could be giving false negative results because of the methodology being used, the state-run Interfax agency reported Thursday citing Russian Health Ministry chief pulmonologist Sergei Avdeev.
“If sampling materials are collected poorly or too lightly, that could lead to a false negative sample,” Avdeev said.
Avdeev identified “sampling time” as another important factor affecting a test’s accuracy, saying that taking the sample “during the early stages of the diseases gives a higher chance of getting a positive result.”
Avdeev also said that Russia’s Health Ministry does not doubt the quality of PCR tests available in the country, including those imported from abroad.
PCR tests are some of the most widely available tests used for Covid-19 diagnosis. The test samples are commonly collected by nasal or throat swab. The tests are used to find active coronavirus infections by detecting the virus’s genetic information, and cannot detect evidence of past coronavirus infections.
Russia’s daily new coronavirus case numbers have remained above 19,000 since Wednesday, putting the total number of recorded cases at 1,712,858.