Coronavirus relapse cases continue to rise in S. Korea | Hacker News Reader

Coronavirus relapse cases continue to rise in S. Korea

en.yna.co.kr

55 pointsjdc26 comments

Scientists agree reinfection is an unlikely explanation for patients who test positive a second time, according to the Los Angeles Times, and note the possibility that testing errors, and releasing patients from hospitals too prematurely, are more likely the reason for reports of patients who retest positive.

“If you get an infection, your immune system is revved up against that virus,” Keiji Fukuda, director of Hong Kong University’s School of Public Health, told the Los Angeles Times. “To get reinfected again when you’re in that situation would be quite unusual unless your immune system was not functioning right.” Fukuda told the paper that it’s more likely patients are being released from hospitals while carrying dormant fragments of the disease that are not infectious, but resemble the virus when tested. “The test may be positive, but the infection is not there,” he said.

https://thehill.com/changing-america/well-being/prevention-c...

The OP article says

> "No secondary infections have been reported from relapse cases, according to the KCDC."

I wish they also talked about symptomatic vs just testing positive. Are there cases where someone got discharged after going through the 2-3 week cycle of symptoms, became free of symptoms and then got sick again ?

That's the more interesting case for me than just testing positive which could be attributed to testing errors

From the article: "Of the 137 cases that have clinical and epidemiological information, 61 showed symptoms again, the KCDC said."

> than just testing positive which could be attributed to testing errors

We know that these RT-PCR tests have about a 30% error rate and the errors are almost entirely false negatives, especially early and late in the infection. There's informed speculation that one of the reasons we're still unsure if kids get it less or just test out less because their immune systems fight it off so well that the load is more frequently under the 'positive' threshhold.

Korean doctors are able to speak for themselves and we should rely on the studies themselves to inform discussion, not hearsay from a third party source about “scientists agree” whatever the heck that means. What do the Korean doctors who are reporting the alleged reinfection think.

The linked article isn't a scientific study and doesn't refer to any studies. It just talks about relapses without explaining how they happen. So an explanation of how they're thought to happen seems entirely appropriate.

It’s most likely dead virus causing a false positive: https://www.cnn.com/2020/04/17/health/south-korea-coronaviru...

> than just testing positive which could be attributed to testing errors

It's a direct quote from an attributed expert in the Los Angeles Times.

But it says they have symptoms again

By secondary infections, they are talking about pneumonia. Not a recurrence of symptoms.

In fact, the article points out that 61 of these cases did have symptoms. What exactly those symptoms were, I'd like to know. Also, I am wondering about the progression of the disease the second time around.

My own experience, the virus lingers after you beat it, waiting to return.

For example, if I have a few drinks or don’t get enough vitamins it starts to come back mildly until I reverse course.

Is it possible that this remains dormant, somehow, similar to herpes viruses? Where could the virus hide? I am not a physician or scientist, but this article indicates that an S protein, like that which is present in covid-19, can bind to ace2 receptors -- so would it be unreasonable to think that it could hide, dormant, in this receptor?

https://www.cell.com/trends/pharmacological-sciences/referen...

Viruses cant hide inside of receptors or the like. When a virus goes latent (the term you are looking for is viral latency), the genetic material of the virus finds a way to hide out inside a cell. The genetic material either floats around inside a protected area of the cell (episomal, think herpes) or actually integrates and becomes a part of your own dna (proviral, think HIV).

I don't know of any conclusive evidence yet that any coronavirus establish an HIV/herpes style latent infection. Of it turns out they do, then, to put it mildly, that is a very very very very big deal and a very very bad problem to have.

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

"The KCDC said it took 13.5 days on average for people to be retested positive for COVID-19 after being released from quarantine."

Maybe they were never fully recovered.

I’m thinking some people pulled strings to get discharged early. South Korea is sequestering people in hospitals if they’re positive, and that’s not exactly a fun experience.

To be clear, things are still looking good for South Korea in general[1], but it's good to know that relapse is possible.

1. https://m-en.yna.co.kr/view/AEN20200418001051325

Are humans typically immune to any and all viral infections that their immune system fights off? Like its just kind of a rule? Either you die or you become immune?

I don't have a link, but I remember reading elsewhere that with other coronaviruses (many cold viruses are in this category), it's thought possible to be reinfected after a while, especially if the symptoms are mild. The worse the symptoms, the stronger and longer lasting the immune response tends to be, which reduces chance of reinfection.

Edit: this may be relevant https://www.npr.org/sections/goatsandsoda/2020/03/20/8190384...

> Researchers do know that reinfection is an issue with the four seasonal coronaviruses that cause about 10 to 30% of common colds. These coronaviruses seem to be able to sicken people again and again, even though people have been exposed to them since childhood.

I read as a teenager this was always due to mutation. Do these viruses not change over time?

Nope. You have to active a full neutralizing antibody based response. Many/most mild infections will be fought off with passive defense measures which wont trigger your body to go through all the effort of generating antibodies against the virus. And even if you do gain immunity, that's only against a given antigen, so the virus can mutate or reshuffle its genome (e.g. hiv, influenza) and make permanent immunity difficult.

(I am not a scientist) I remember seeing someone talk about the risk of re-infection when this all started. They said that they only way to fully know if the virus has mutated would be to do a full sequence of the virus comparing the first infection with the second. It will be interesting (and possibly scary if has mutated) to see what is causing this second re-infection of patients that are supposedly recovered.

Here's an article talking about people getting re-infected at the end of Feb. https://www.livescience.com/coronavirus-spread-after-recover...

Visualized phylogeny of the novel coronavirus: https://nextstrain.org/ncov/global

> if the virus has mutated

From the article: "The new coronavirus is mutating—but that’s not a bad thing"

* "Just because the virus is mutating doesn’t mean that it’s suddenly going to become more dangerous… the bulk of the mutations that appear as a virus spreads are either harmful to the virus itself (meaning it is less likely to survive or replicate) or don’t change how it functions."

https://www.popsci.com/story/health/covid-19-coronavirus-mut...

From the study: "High incidence of asymptomatic SARS-CoV-2 infection"

* "the hospital length of stay for patients with a large number of transmission chains is shortening, indicated that the toxicity of SARS-CoV-2 may be reducing in the process of transmission.

https://www.medrxiv.org/content/10.1101/2020.03.16.20037259v...

From the summary post for: "Discovery of a 382-nt deletion during the early evolution of SARS-CoV-2"

* "The researchers sequenced the genome of a number of COVID19 viruses from a series of infected patients from Singapore. They found that the viral genome had a large deletion that was also witnessed in past epidemics of related viruses (MERS, SARS), especially later in the epidemic. The form with the deletion was less infective and has been attributed to the dying out of these past epidemics. In other words, COVID19 seems to be following the same evolutionary trajectory. Discovery of a 382-nt deletion during the early evolution of SARS-CoV-2"

https://www.reddit.com/r/COVID19/comments/fl3yqg/some_sarsco...

Covid-19 mutates about 2x a month. https://bedford.io/blog/ncov-cryptic-transmission/

This doesn't mean the virus has changed enough for your body to not recognize it. But it can be used to map transmission chains.

We know where Covid-19 started, but scientists have also used mutation rates to correct our understanding of when HIV jumped to humans.

We know where it was first identified as a new virus, not where it started.

There are numerous reports of Italy’s search for patient zero pointing to it being there before China.

“ Remuzzi says he is now hearing information about it from general practitioners. "They remember having seen very strange pneumonia, very severe, particularly in old people in December and even November," he says. "This means that the virus was circulating, at least in [the northern region of] Lombardy and before we were aware of this outbreak occurring in China."”

https://www.npr.org/2020/03/19/817974987/every-single-indivi...

It's not clear but does this mean they're still contagious regardless of symptoms (since many are asymptomatic)?

> "Of the 137 cases that have clinical and epidemiological information, 61 showed symptoms again, the KCDC said."

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