[arcticbull]

Sure, but that doesn't mean they... won't go away. In fact, I'm pretty confident all signs point to the fact they will go away. In fact you get ground glass opacities with H1N1 inflenza [1]. I guess the question is "functional asymptomaticity" vs "actual asymptomaticity". Like, if it's not bad enough for people to even notice does it really matter?

[1] https://pubs.rsna.org/doi/full/10.1148/radiol.10092240

[8note]

Do those count as a comorbidity though?

If coronavirus goes around again, that could raise the death rate

[arcticbull]

There's no evidence to date that people are being re-infected. They may in the future, but to date, no such evidence exists. There are some people who tested negative before who are testing positive now, but that is much more likely to be false negatives and/or false positives.

It would be pretty novel for the human immune system to clear out the disease on it's own, then a few days later forget how to do that, and become re-infected. SARS-COV-1 saw immunity conferred for 2-3 years. [1] I suspect something similar is likely here, probably for a shorter duration due to the more limited severity, but long enough to get us to a vaccine.

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

[greedo]

And there's no evidence to date that people who test for antibodies are immune to future infections.

[arcticbull]

Ah my old friend greedo. That's how it normally works, this time could be different, but we have no reason to believe that.

Generally for as long as you show antibody response you won't be re-infected because that's what antibodies do. The link I provided to the study I referenced was specifically for the purpose of, and I quote: "to assess SARS patients’ risk for future reinfection."

"To be clear, most experts do think an initial infection from the coronavirus, called SARS-CoV-2, will grant people immunity to the virus for some amount of time. That is generally the case with acute infections from other viruses, including other coronaviruses." [1]

If you think this time is different the burden of proof is on you to provide studies and not provide unsupported, unsubstantiated conjecture.

[1] https://www.statnews.com/2020/04/20/everything-we-know-about...

[greedo]

We have no idea how long lived the antibodies we develop in response to SARS-CoV-2 last. And obviously, an initial infection to COVID-19 will generate antibodies that will immunize the patient, as long as the antibodies persist. Don't you think that if this was a foregone conclusion, we'd be able to demonstrate that? Isn't it odd, that with people having been infected and recovered months ago, that no one is saying how long the antibodies persist?

In science, it's incumbent on those making the claim to provide studies and proof. That means you...

And to say that this is unsupported, unsubstantiated is ridiculous, and you know it. It's straight from the WHO's mouth.

[arcticbull]

> It's straight from the WHO's mouth.

Nothing I said contradicts the WHO.

> Don't you think that if this was a foregone conclusion, we'd be able to demonstrate that?

I'm sorry, do we need to re-prove how the immune system works? Why re-demonstrate the utterly obvious?

> Isn't it odd, that with people having been infected and recovered months ago, that no one is saying how long the antibodies persist?

No, because it hasn't been long enough. I'm confident that research is under way.

[djsumdog]

but it would go against everything we know about viruses and our adaptive immune systems. I know there are some vaccines with lower take rates. Hep B requires 3 injections and only has a 60% change of generating antibodies.

But an immune response from an actual virus should last for at least a few years. There are situations where you can get reinfected later in life if you're not exposed or given booster shots (likes Shingles).

Is there evidences that our adaptive immune system only generates short lived antibodies, and for what families of viruses?

[jacquesm]

https://www.aljazeera.com/news/2020/04/warns-coronavirus-imm...

[arcticbull]

Nothing there is at all incompatible with what I had to say. In context, the WHO is saying that getting the disease once may not be a lifetime immunity to COVID guarantee and shouldn't be used as the basis for issuance of something along the lines of yellow fever prophylaxis certifications like these [1].

I agree. In fact, its highly unlikely, as with coronaviridae we've seen that the milder the disease the less likely you are to obtain long-term immunity. Even SARS, a much, much more serious disease, gives you 2-3 years as per my reference.

However, that's not what GP was arguing. GP argued broadly that "people who test for antibodies [may not be] immune to future infections." That's extremely unlikely. The question is how many people, and for how long, and then how do we utilize that information. Broadly speaking a positive test for antibodies means you're pretty likely immune at the time the test is taken. Of course the question is how that antibody response changes over time.

I was pretty clear about that: "Generally for as long as you show antibody response you won't be re-infected because that's what antibodies do."

The WHO is saying don't issue one-off certificates of immunity for life on the basis of testing positive for antibodies at one point in time before we know more. I agree.

I suspect a round of infection is likely to tide us over to a broad vaccination program, but we need a study.

[1] https://thegate.boardingarea.com/wp-content/uploads/2016/04/...

[greedo]

Hi Artic, here's a new study you might find interesting. It seems to disagree with your contention that immunity is normal for coronaviruses.

https://www.technologyreview.com/2020/04/27/1000569/how-long...

[wavegeek]

> I'm pretty confident

powerful argument there, not.

With SARS1 there was continuing damage post 6 months.

[arcticbull]

SARS-COV-1 has a two orders of magnitude higher fatality rate, so one would imagine the damage would be substantially worse. Is it really a stretch to believe that level and quantity of damage correlate both to recovery time and to mortality rates? Further, were there asymptomatic SARS-COV-1 cases?

SARS-COV-1 had an IFR (not CFR) of 14-15%. Broken out, it's less than 1% for people younger than 25, 6% for those aged 25 to 44, 15% for those aged 45 to 64, and more than 50% for people 65 or older, officials said. [1]

On the other hand SARS-COV-2 has an IFR of somewhere in the lower quartile of the range 0.1% to 1%, trending to around 0.3%.

Not to mention, I argued that lung function would recover, to which you said "strong argument, not [the much worse disease saw lung function recover in 6 months]" which implies you were actually supporting my argument not refuting it.

The coronaviridae family is huge, and fatality varies from ~0% in the 15% of common colds they cause to 0.1-1% for COVID to 15% for SARS-COV-1 to 50% for MERS. I can't stress this enough. SARS-COV-1 and MERS are not SARS-COV-2, they are much worse diseases.

[1] https://www.cidrap.umn.edu/news-perspective/2003/05/estimate...