We are getting some patients who were initially positive of RT PCR for Covid. But in retesting after 15-20 days or even 20 days after those patients remain still positive. Is it for dead RNA particle in the posterior nares or virus can remain viable for more then 20 days also. What to do to make those patients negative?
If the patient isn't acutely and severely sick, the best course of action is probably to monitor and wait for the infection to run its course (under quarantine, of course). The alternative would be to use antivirals, but what would be the benefit (which would have to outweigh the risk of side effects)?
Thanks Buxbaum! Most of the patients we are getting asymptomatic! So, no role of antivirals as you said. Are there option to detect active virus and inactive RNA particles?
I can only think of two possibilities, growing virus on cell cultures and looking for virions under the electron microscope. Expensive, time-consuming, you'd need BSL 3 containment and the expertise.
Perhaps you have in your country an organisation like the CDC in the USA or the RKI here in Germany, where people specialise on infectious diseases? A collaboration would be your best bet, IMHO.
Thanks! We are from third world! We have no option for culture or electron microscopy so far.
Rajat Sanker Roy Biswas
RT-PCR positive does not necessarily translate to having infectious virus. Remember the procedure only targets some components of the viral RNA which could still be picked by RT-PCR even if the virus is not an intact particle. This explains why in some countries like Singapore, RT-PCT test is not repeated after the initial diagnosis and that positive cases are discharged following two weeks of isolation. It is believed that even if the patients turn out positive after two weeks of the initial diagnosis, they cannot transmit the disease to other persons. Nevertheless, as rightly suggested by @Engelberg, You can attempt to do virus culture from the RT-PCR positive samples if you have the required biosafety level in your lab. Otherwise, I don't think you should worry about that especially that most of your patients are even asymptomatic.
Regards
Bashir
PCR can remain positive for a longer duration depending on multiple factors, even if the patient is asymptomatic for a considerable duration of time. Though after 7th nonsymptomatic day cases are generally considered as noninfectious. Most of these cases become PCR negative in the course of time. We have experienced recovered patients with a trace positive PCR until 45day from the first positive PCR. In such cases usually, no treatment requires if the patient does not re-express COVID-19 symptoms and the hematological/Biochemical markers are in a favorable range.
Regards
In asymptomatic people if PCR remains positive beyond 14 days after the first isolation of COVID-19 this usually represents asymptomatic viral shedding.
Hi,
What was the Ct values in Day 1 and Day 15? As others mentioned PCR can show positive even after recovery.
https://jamanetwork.com/journals/jama/fullarticle/2762452
Hope this helps.
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