EDIT: to clarify: in my hospital there were colleagues who tested positive, isolated, had no symptoms, went back to work, still no symptoms. After a few days symptoms are back and they tested positive again

They're working in a hospital so they'll catch everything.

Given the (currently) very low numbers of these "apparently relapsed" cases versus the total recovered cases, I think it is most likely.

- Similar sympthoms but different disease (flu?)

- False negatives, and so people were still actually sick

In addition, I wonder if those patients had distinct clinical features compared to others. In absence of more data (and these cases are very uncommon) it is hard to tell.

Probably a good idea would be to do a study with periodical follow up of a large cohort of discharged patients. This would probably give better indication.

I feel that the “false positive” answer is often quickly given, without considering that it is likely that some people that get the virus have it flair up again. Perhaps it is caused by wishful thinking: reactivation is scary so let’s find a less scary reason?

If there are patients who test negative for several weeks but then relapse and get clinically sick with COVID-19, we'll have cause to worry. On the other hand, if this was a common phenomenon, it'd be happening in China already.

https://www.microbe.tv/twiv/twiv-597/

https://www.biorxiv.org/content/10.1101/2020.03.11.987222v1....

https://covid19usa.io/

Edit: Adding my website for tracking coronavirus cases over time in USA state and counties. Original Show HN here: https://news.ycombinator.com/item?id=22778152

But to the patients that got sick again. "Bad test" would be the best outcome yes, but I know, that with herpes virus for example, you can never really get rid of them. Your immune system defeats them, but some virus cells remain in stasis somewhere sleeping - and resurface, if your stress level is high enough. So it would not surprise me, if this coronavirus might have similar traits.

https://en.wikipedia.org/wiki/Herpes_simplex

macrophage

So .. I leave this debate to more knowing persons.

That's arguably Greek ;-)

— James Davis Nicoll

We share Toll Like Receptors (TLRs) homology with drosophila. That's how ancient innate immunity is.

This makes no sense. It's not the antibodies, it's the virus itself - it can mutate.

So does this mean they're symptomatic again, or just testing positive?

Was it COVID the first time? Was it COVID the second time? Was it stress, or his body adjusting to being in the same environment 24/7 (rather than spending half his day outside the home)? We may never know. An antibody test would show if he'd had it at least once, but that could well have been 2 back-to-back colds with asymptomatic SARS-CoV-2.

Not a doctor, but just my understanding from [1] though I start seeing people challenge that pattern [2].

[1] https://www.youtube.com/watch?v=BtN-goy9VOY

[2] see responses to: https://news.ycombinator.com/item?id=22786656

Stands to reason that it would apply to COVID-19 too.

HIV - https://upload.wikimedia.org/wikipedia/commons/thumb/0/0e/Hi...

It takes time as someone above said to work out whats happening and what to do - https://www.youtube.com/watch?v=Z48SZykpQeY

The thing that in my mind sorta kills this "reinfection" argument is our previous experience with SARS virus [1]. Figure 1 of the paper shows IgG reactivity for up to 3 years. Anecdotally, I've heard from my immunity bioinformatics colleagues that the spike protein that is recognized by the immune system is very well conserved.

I haven't seen a ton of great evidence that have really pushed my priors against the conclusion that these handful of cases are better explained somehow by faulty testing/some other combination of complication. As always, willing to adjust these priors if given compelling evidence. :)

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/

In year 2000 computer terms, the virus doesn't just need the bytes of the VBS file, it also needs the email header that says "ILOVEYOU".

Only in the same way as blood is people. Viruses are a DNA/RNA core packaged in proteins plus a borrowed disguise that acts like an envelope and would put the crownb part in coronavirus. Some are naked and lack the envelope, other (i.e coronavirus) not.

> A 60-year-old woman from Pune who tested negative for coronavirus died three days after being discharged.

> However, on April 4, she was rushed to Sassoon Hospital in Pune, where she died even before admission. When her sample was tested again, it turned out to be positive.

[0] https://economictimes.indiatimes.com/news/politics-and-natio...