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.
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.
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.
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?
This should be something that can/will be resolved by testing. I find it unusual that no medical authority is going on record as saying there's any long term immunity granted by infection, and that the WHO is being extremely clear in the lack of evidence to support such a conclusion.
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.
""There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.""
They were prompted to issue this because some people were touting this idea of immunity being granted perpetually and allowing people to safely return to work.
"Broadly speaking, a positive test for antibodies means you're pretty likely immune at the time the test is taken."
That's in complete contradiction to what the WHO is saying. Read carefully: There is no evidence.
You're using circular arguments to provide bad information. Something you've consistently been doing.
"...but we need a study."
Why? You've said it's unlikely to be different than other viruses. Of course we need a study, because we don't know.
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/