New test will show the level of infection and severity of coronavirus in a patient
Russia has created the first test that detects not only the presence of coronavirus in biomaterial, but also its quantity. Any biological material is suitable for investigation: nasopharyngeal and oropharyngeal smears, sputum, bronchoalveolar fluid, and blood plasma. Today, most tests for coronavirus use only nasopharyngeal and oropharyngeal smears, but the pathogen can be detected there only in the first days after symptoms appear. The amount of SARS-CoV-2 in the swab gives an idea of the viral load of the infected person.
“This information will enable doctors and epidemiologists to obtain qualitatively new information concerning the degree of infectiousness of an infected person, predict the severity and duration of the disease, control the reduction of viral load in dynamics, in other words, the effectiveness of treatment”, said Svetlana Yatsyshina, head of the scientific group for development of new methods of diagnosis of acute respiratory diseases and the reference center for monitoring of infectious agents of upper and lower respiratory routes of the Central Research Institute for Epidemiology of Rospotrebnadzor.
In the first days after the incubation period, the content of the virus in swabs can be high, even if there are no symptoms of the disease. Infected people may infect others without suspecting it. With the new test they can be detected and isolated in time.
The new test detects a minimum of 500 copies of the virus genome in 1 ml of the test sample, and the maximum amount of detected RNA is unlimited. The concentration can be accurately calculated within the range of 500 to 300 million RNA copies in 1 ml. Such sensitivity is common for modern PCR diagnostic methods, experts say.
“Detection of SARS-CoV-2 coronavirus RNA in sputum in high concentration correlates with a more severe course of the disease and is an unfavorable prognosis. On the contrary, low concentration of coronavirus RNA or its rapid decrease is a favorable sign”, – said Svetlana Yatsyshina.
The cost of the new test remains at the level of standard PCR with real-time detection.