SRINAGAR: Principal of Government Medical College, Srinagar, Dr. Samia Rasheed on Monday clarified that “a person can be positive on one day and a few days later can test negative due to a lower viral load.”
The response comes hours after questions were raised on the authenticity of the COVID tests being conducted at the Government Chest Disease Hospital, Srinagar.
“In the particular case that was highlighted, we stand by our report. A person can be positive on one day and a few days later can test negative due to a lower viral load,” tweeted Dr. Samia.
Many people including a senior journalist, who were tested positive for COVID 19 at Chest Disease hospital laboratory a few days back, tested negative for the virus at SKIMS Soura.
“Based on our initial internal review, this outcome is a result of the difference in viral load across a few days. This must not be misconstrued or misinterpreted to suggest either of the testing facilities is not up to the mark. Request the public to place trust in the healthcare system,” Dr. Samia said
A senior Microbiologist requesting anonymity said a majority of the samples undergo Real-Time Polymerase chain reaction testing, RT-PCR.
“They are only 60 percent sensitive. (Which means they are not 100 percent accurate). However, for early diagnosis of individuals with severe acute respiratory syndrome coronavirus 2 (Sars-CoV-2), which causes Covid-19, a test called cartridge-based nucleic acid amplification tests (CBNAAT) is being done. This test is more sensitive and specific than RT-PCR. There is 100 percent accurate. It can declare results in 15 minutes unlike the RT-PCR which takes six hours,” he said.
The doctor said they have received 400 cartridges so far and 600 more are being imported. “The variations in RT-PCR tests can be because of preanalytical errors. Ideally, a sample should be taken at a proper site where the presence of the virus is maximum. If the swab is not taken properly, there can be a variation. Sometimes, the samples are not taken properly which leads to variation,” he said.
The microbiologist noted that they are discharging duties with utmost professionalism and competence. “The thing is that we receive a lot of samples every day. The tests should be done twice or thrice to cross-check. Suppose, if a test comes positive at CD Hospital, and SKIMS shows it negative, there is a chance that even the latter might have shown erroneous results. So cross-checking is important,” he said.