Tests for COVID-19 may give erroneous results primarily due to late collection of material for research. This explanation was given by the chief freelance epidemiologist Ministry of Health of the Chelyabinsk Region Alexander Vygonaylov in a conversation with the publication Ura.ru.
According to him, after six days from the onset of the disease, the study of nasopharyngeal secretions is usually ineffective.
In addition, Vygonyaylov noted that the correct intake and transportation of material affects the accuracy. He emphasized that the analysis should be done within the next two to three days from the moment the smear is placed in saline, however, due to the congestion of the laboratories, the study begins to be carried out 7-14 days after sampling.
“The likelihood of detecting the pathogen of the coronavirus in this case is further reduced. And a late positive result does not allow full work with contact persons and prevent the spread of the disease,” Vygonaylov said.
Previously Rospotrebnadzor set the deadline for the coronavirus test – it should not exceed 48 hours. The norm was established by the decree of the head of Rospotrebnadzor Anna Popova . The decree also states that the minimum daily coverage of PCR tests must be increased from 150 per day to 200 per 100 thousand of the population.