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Q. Why does my COVID-19 RT-PCR test results come positive on the first day, and negative after 24 hours?

Answered by
Dr. N. Ashok Viswanath
and medically reviewed by iCliniq medical review team.
This is a premium question & answer published on Mar 15, 2022

Hello doctor,

I had tested positive for COVID-19 around five months back. However, the next day my test result was negative.

I was again tested positive 14 days back and subsequently, the next day the result was negative. Yesterday, I was tested positive again and today also the result was negative.

I am taking the tablet Olmetec 20 mg, the tablet Esidrex 12.5 mg, the tablet Nebilet 2.5 mg, and the tablet Zyloric 200 mg.

All the positive test results were shown by RT-PCR (reverse transcriptase-polymerase chain reaction) test, done by different laboratories and in different countries. I did several self-antigen tests also, after my positive RT-PCR results but all of them came out to be negative.

I never had any symptoms. No one around me has ever been tested positive or infected.

All this means that I have been infected three times within five months, getting healed within 24 hours, and never showed any symptoms.

Since this cannot be the case and there must be a different explanation for it so please explain it to me.

Thanks.

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#

Hello,

Welcome to icliniq.com.

I understand your query.

While comparing the rapid antigen detection kit, the sensitivity of the RT-PCR (reverse transcriptase-polymerase chain reaction) test is very high. It can detect even very few viral particles which can be otherwise missed with rapid antigen detection kits. Though it is highly sensitive and highly specific, still RT-PCR test cannot differentiate between live and dead virus particles. There could also be false positive RT-PCR test results due to issues like low-level reactions and sample contamination at the time of sample collection. Another reason for such occurrence could be attributed to persistent intermittent viral RNA (ribonucleic acid) shedding after symptomatic or asymptomatic COVID-19 infection for many months.

The next time, when you are getting tested for COVID-19, you can ask for the genes which are detected and CT (cycle threshold) value if the positive result comes. CT value of more than 35 indicates a low positive. This kind of issue is seen widely with the COVID-19 virus, but the exact cause and its significance are poorly understood.

Since you do not have any symptoms and no one around you has ever been tested positive or infected still date so there is no need to worry.

Hope I am able to clarify your doubt.

Take care and have a great day.

Hi doctor,

I have attached the reports of the latest two tests taken within approximately nine hours of a gap for better interpretation of the results.

Thanks.

#

Hello,

Welcome back to icliniq.com.

I understand your query and I have gone through the attached documents (attachments removed to protect the patient's identity).

The first RT-PCR (reverse transcriptase-polymerase chain reaction) test result is positive and the N-gene is negative and, the second test result is negative.

In the test report with the positive test results, the 2019nCOVRNA is positive, but CoV N-gene is negative. In cases of repeated positive test results after an episode of COVID-19 infection, which may be symptomatic or asymptomatic infection, the N-gene is considered as the main component in correlation with COVID-19 IgM testing for determining the re-positiveness of the result. The detected 2019nCOVRNA particles could be present due to an old infection further leading to the presence of fragmented viral particles which may be found intermittently in the nasopharynx. These could be detected in the RT-PCR test. One of the drawbacks of the RT-PCR test is that it cannot differentiate between live and dead virus particles.

In the absence of any symptoms or any illness, do avoid the COVID-19 RT-PCR test.

Take care and have a great day.


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