Key passage from the text:<p>Kim also said patients had likely “relapsed” rather than been re-infected.<p>False test results could also be at fault, other experts said, or remnants of the virus could still be in patients’ systems but not be infectious or of danger to the host or others.<p>“There are different interpretations and many variables,” ...
Do we have any data on South Korea's tests and their false positive/negative rates? Even a couple percent would lead to several cohorts of "tested positive but weren't" and "tested negative but still were actually positive", I'd think.
Where's the study and data? What's the time frame we're looking at here?<p>This German study (<a href="https://www.medrxiv.org/content/10.1101/2020.03.05.20030502v1" rel="nofollow">https://www.medrxiv.org/content/10.1101/2020.03.05.20030502v...</a> -- see the graphs near the end of the PDF) suggests that viral RNA may be detectable in recovered patients for 3 weeks after symptom onset, or longer (the study seemed to stop testing after 3 weeks, despite some recovered patients still testing positive for viral RNA). But they were unable to isolate <i>live virus</i> after about a week post-onset.<p>Could this be what we're seeing?<p>If you're still worried, I recommend looking at this small study on macaques designed to test immunity (<a href="https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1" rel="nofollow">https://www.biorxiv.org/content/10.1101/2020.03.13.990226v1</a>). They found that the macaques did develop immunity and were able to fight off the virus on reinfection. If we compare with the this study (<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/" rel="nofollow">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/</a>) on the development of immunity in response to the original SARS virus (I'm not sure on the exact mechanism of immunity, but if the body's immunoglobulin response targets the spike protein, then it's probably similar), we should probably expect antibody production to continue at least a year after infection, if not for 3-4 years after.
The issue is talked about at 7:59 in this video <a href="https://youtu.be/gAk7aX5hksU" rel="nofollow">https://youtu.be/gAk7aX5hksU</a> (Leading COVID-19 Expert Professor Kim Woo-joo from Korea University Guro Hospital)
The article doesn't make it clear how many such cases there are:<p>> The South Korean figure had risen from 51 such cases on Monday.<p>> "The number will only increase, 91 is just the beginning now"
Layman here. Curious: if this is true, that you don't gain long term immunity to SARS-2 by catching COVID, would that have any implications on potential vaccine in the future? Does this mean, this virus is something we cannot build a vaccine for? Does this mean even if we have an approved vaccine, it would likely have a very low probability to protect us? Or do RNA vaccines work in a way that affects our immune system that's entirely different than how immune system builds immunity against the virus itself?
Could this turn out like HIV where there is an initial infection period followed by some dormant period and then another period where it causes more problems for the host again?
I feel like we're about to learn way more about viruses than we thought we knew. It's like how NYTimes "scientists" only recently learned that gut bacteria is our friend...