In the early months of the coronavirus pandemic, healthcare workers analyzing test results began seeing something strange, i.e., patients who had already recovered from COVID-19 would sometimes inexplicably test positive on a PCR test weeks or even months later. 

The new study finds, Some virus RNA can be reverse transcribed and inserted into the human genome, which may explain why some people who had already recovered from Covid-19 would sometimes inexplicably test positive on a PCR test weeks or even months later.

Researchers from the Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology (MIT) in the US, showed that genetic sequences from the RNA virus SARSCoV-2 can integrate into the genome of the host cell through a process called reverse transcription. These sections of the genome can then be "read" into RNAs, which could potentially be picked up by a PCR test.

The results are published online 6 in the journal Proceedings of the National Academy of Sciences. SARS-CoV-2 is not the only virus that integrates into the human genome. Around 8 percent of our DNA consists of the remnants of ancient viruses. Some viruses, called retroviruses, rely on integration into human DNA in order to replicate themselves.

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