The COVID-19 virus has an incubation period, so when can we get accurate test results after contact with a confirmed patient?
In this regard, the Director-General of Health Tan Sri Noor Hisham pointed out that the accuracy of RTK-Ag and RT-PCR test results will depend on the infection period at the time of sampling.
Once exposed to a confirmed patient, rapid antigen testing (RTK-Ag) can be used on days 3 to 7 to identify infection. In contrast, reverse transcription-polymerase chain reaction (RT-PCR) detection can be identified as early as day 2 to day 14 after infection.
Currently approved RTK-Ag test kits need to have at least 95% rate sensitivity and 95% specificity. But this has the potential to result in false positive or false negative results in 5%.
Factors leading to false positives include cross-infection of patients with COVID-19 or contamination with viruses in the environment; while factors leading to false negatives include using wrong sampling techniques and collecting samples outside the infection period.
As for RT-PCR, which is currently the gold standard for detecting COVID-19, it can more specifically identify the viral nucleic acid (viral genetic material) of the COVID-19 virus with a rate sensitivity of 99.9% and specificity of 100%.
In addition, Director-General of Health Tan Sri Noor Hisham also pointed out that there is no need to repeat the test after the confirmed person completes isolation, because very sensitive tests such as RT-PCR can still detect the genetic material of the virus in respiratory samples, which can take up to 2 to 20 minutes. For three months, during viral shedding.
In any case, during the viral shedding period, the virus cannot reproduce and the individual cannot infect others.
