The number of conducted tests for confirming Covid-19 infection is not matching with the number of suspected patients across the country, as 30 per cent of the asymptomatic patients still remain out of diagnosis.
In this situation, experts suggested starting rapid test immediately by using both PCR and serological method for more accurate case detection. They also suggested going for both RNA and serological test, if possible.
They said the accuracy of test depends on when the patient is coming for test as well as whether the sample is collected from proper part of his/her body.
Besides, in most death cases, no virus is found, as samples from dead persons are not collected properly, they added.
In the country, Covid-19 is tested in 17 labs at the rate of as high as 1,740 samples a day, although testing capacity of the labs is over 4,500 a day. So far, 14,868 tests have been done, which is far below the standard. Another 11 labs will start testing soon.
Chairman of Virology Department of Bangabandhu Sheikh Mujib Medical University (BSMMU) Professor Dr Saifullah Munshi said coronavirus will not be found in cough and throat of an infected person after seven days.
Moreover, 30 per cent of patients, infected with the virus, is asymptomatic, and they remain totally out of purview of any test.
"If a patient comes within seven days (of infection), RNA and PCR tests are applicable for him. If the patient comes after eight days, we should go for antibody test."
Referring to sensitivity of tests, published by New England Journal, Dr Saif said if an infected person comes between one to seven days, the sensitivity of PCR test is 66 per cent and that of antibody is 38 per cent, which means PCR test is more effective here.
If a patient comes between eight to 14 days, the sensitivity is 54 per cent for PCR test, and 70 per cent for antibody test.
"In our country, we've observed that people are usually coming for test after eight days, as they cannot decide whether to go to doctors or not. I suggest administering both the tests, if there are symptoms. One type of test may not be enough (to detect properly)."
