Does recovering from Covid 19 cause immunity to new infection by Sars Cov2 ?
The WHO warns that it is not proven that we acquire immunity to Sars Cov2. If we don’t we are pretty much doomed. However, I don’t see how people could recover without developing immunity or develope immunity without memory with human immune systems. Here, as often, the burden of proof is placed on the optimistic hypothesis. Here again (third time) I dare to be optimistic (third time’s a charm).
At Daily Kos Mark Sumner has an excellent post on the topic. I cut and pasted my comment below. I agree with everything he wrote except the part about the common cold (which is a syndrome caused by one of dozens or hundreds of diffferent known viruses). In particular a key open question is whether all people who recover are immune but some are more immune than others (as he notes it is known that some have low anti Sars Cov2 antibody levels). Also it isn’t known if and when there will be new strains which evade the currently existing neutralizing antibodies.
His post is brief and too good to excerpt. Just click this link (then come back to read my post or not — it’s not at the same level)
First there is strong evidence that exposure to Covid causes people to make neutralizing antibodies, you mention this. Here is my first google hit . In that article, the cell making such an antibody was immortalized by fusion with a leukemic cell and so there is a neutralizing monoclonal which can, in principal, be mass produced and used as a treatment. The problem (as usual) is that it isn’t proven that it works and such proof takes a lot of time and money.
I don’t think there are viruses which infect us again and again. We are infected by new viruses (here I include mutants of the old virus as in seasonal flu). The common cold is a syndrome not a virus. There are dozens to hundreds of known viruses which cause colds (with similar symptoms). By your definition we get many different viral diseases with similar symptoms.
There is certainly a risk that Sars Cov2 will mutate in a way such that it is no longer neutralized by currently neutralizing antibodies, and so there will be a new epidemic even if enough people are vaccinated to provide herd immunity to Sars Cov2 1.0 (influenza does this which is why there is seasonal flu). It is also possible that this won’t happen (there wasn’t a smallpox 2.0 which infected people who were vaccinated).
Importantly, antisera against Sars Cov2 can be tested (in cell culture) against isolates from different continents. So far, I think, the evidence is that sera (polyclonal) antibodies which block one strain block all existing strains (which sure doesn’t mean all strains which will ever exist). There is a vaccine (good old fashioned killed virus vaccine, which has protected Rhesus macaques from infection by Sars Cov2 squirted in their lungs b
If our immune system can’t stop Sars Cov2, then how to people recover ? Why has anyone gone from positive to negative ?
Again, we don’t get the same common cold virus again and again. There are many different cold viruses. Most are picornaviruses (double stranded circular RNA genome, small, like polio) some are coronaviruses, and some are adenoviruses (which cause fierce colds).
I think the WHO is putting the burden of proof on the hypothesis that, whatever happens in us to beat one Sars Cov2 infection lasts for a while. If this were not true, it would be unique (I think).
update: there is now more direct evidence in a non peer reviewed preprint here
Neutralizing antibody responses to SARS-CoV-2 in a COVID-19 recovered patient cohort and their implications
Fan Wu, Aojie Wang, Mei Liu, Qimin Wang, Jun Chen, Shuai Xia, Yun Ling, Yuling Zhang, Jingna Xun, Lu Lu, Shibo Jiang, Hongzhou Lu, Yumei Wen, Jinghe Huang
“neutralizing antibodies (NAbs)”
Plasma collected from 175 COVID-19 recovered patients with mild symptoms were screened using a safe and sensitive pseudotyped-lentiviral-vector-based neutralization assay. [skip]
SARS-CoV-2-specific NAbs were detected in patients from day 10-15 after the onset of the disease and remained thereafter. [skip]
Notably, among these patients, there were ten patients whose NAb titers were under the detectable level of our assay (ID50: < 40)
So according to We et al 165 out of 175 people had produced antibodies which prevent infection of cells. So this is evidence that people recover because of acquired immunity. On the other hand, not all subjects had measurable quantities of the antibodies (and the measure is what dilution blocks virus entry). So an exposed and immune passport would be unreliable — those 10 people are assessed as still vulnerable. This isn’t the end of humanity (165/175 is enough for herd immunity to get R under 1). But it matters for policy (as WHO insisted). Also “remained thereafter” doesn’t mean forever. It can only mean up until now which is, at most, months after the recovery (even if the blood was collected as soon as some people had recovered).
While I share most of the views expressed in this post, I have a problem with this: “If we don’t we are pretty much doomed.”
Uh, no. For one thing, it is feasible that a vaccine could elicit a consistent, reliable protective immune response that isn’t reliably elicited in everyone who is infected.
Beyond that, most patients with AIDS, Herpes simplex or TB infections don’t mount protective immune responses, but they aren’t “doomed.” Happily, there are drugs for TB, Herpes and AIDS that mean patients aren’t doomed. Let’s give pharmacy some props here, eh?
“If we don’t we are pretty much doomed.”
We are not doomed.
In the short run, we may well see horrible numbers of dead or permanently damaged people, but most cases will probably still be mild, maybe even too mild to notice except by testing for antibodies.
It is most likely that recovery will grant immunity for some period of time. If that time is as long as a year, we will need annual vaccination. If it is longer, so much the better. If it is less, we will need a much stronger health care system to handle additional patient loads and more effective treatments. It would not hurt to have both of those things in any case.
@joel while I agree with everything in your comment, I note that you added the word “everyone” which does not appear in this official World Health Organization publication https://twitter.com/WHO/status/1253995619921821698?s=20
It makes a difference. They did not “everyone” (or “all” or anything to that effect) , I think my interpretation is the reasonable plain English interpretation of what they wrote (which can’t possibly be what they meant to write).
I would say there is hope if and only if a large enough fraction of people develope immunity that R_t is less than one even without unsustainable social distancing. If 10% of infected and recovered people are vulnerable, then the epidepic will stop when 10/9 times as many have been infeced as would stop if if 0% risk reinfection.
Similarly a vaccine can produce herd immunity even if it doesn’t immunize everyone who takes it. I do doubt that a vaccine can produce stronger immunity than the actual organism. I will hazard a guess that such super vaccine will be invented some time in the next 1000 years, but they don’t exist yet.
Some still vulnernable but most immune is enough to save humanity.
By the way, when I state conditions for any hope, I do mean any. i snuck in the word “unsustainable”. If it is not possible to keep R less than one, humanity will become exitnct. Clearly this is very very unlikely (such extinctions for no fossilizable reason are not found often in the fossile record). I am confident that some of us would survive even with no ability to become immune to Covid 19. For one thing if there are only 10000 people left, social distancing becomes rather easy.
—————stuff below is not worth your time to read ——————-
To go on and on and on. The officlal W.H.O. publication to which I provided the link makes a very strong claim. they don’t qualify with something like “long lasting resistence” so they assert that someone who just recovered killing off the last Sars Cov2 particle is vulnerable. They do not include “everyone” or “all”. They do not write that they know of no evidence — they assert none exists anywhere including obtained in the past 5 minutes in a lab or hospital or clinic somewhere. The claim to know that something doesn’t exist is a claim of incredible knowledge. Only the clairvoyant or mniciant can plausibly claim such knowledge.
I am reminded of 2 journalistic horrors from 2016. The NY Times headline that the FBI sees no clear evidence of a link between the Trump camptaign and the Russian goverment. This is false (“sees “here clearly meaning believes they have) . The FBI had, at that point, sought and obtained FISA warrants on two former members of the Trump campaign. So they asserted they had probable cause which is more than clear evidence (and judges appointed by Republican Presidents agreed).
No one at the NY Times could know what had been and had not been perceived by any FBI employee. The headline inadvertantly claimed vast clairvoyant knowledge.
The other is the AP publication which falsely asserted that most people who had met with H Clinton had donated to the Clinton foundation. The claim is absurd and was plainly false. The publication omitted the necessary qualifier most people other than employees of the US government or of foreign governments. That false publication (with the AP refused to correct or delete for a while) was also a tweet. Clearly WHO and the AP do not understand that their tweets are publications. At least the WHO publication contains a link to a longer publication (the AP one did not even though the AP managing editor claimed that it did (her claim that she edited rather than collecting a salary for a job that she did not bother to actually do is .
@joel you have accused me of Talmudic Ad Hominem. Truer words were never typed. Sorry (but I did clearly type that this stuff is not worth reading).
Definitely don’t read this one.
OK so I will now be irritating in a 4th language after English Hebrew and Latin.
The statement “non ci sono prove che is guariti da Covid 19 hanno acquisito resistenza” might be true. the key word here is “prove” which can’t be translated by any single English word. It sounds as if it means “proofs” but it doesn’t. It is more nearly translated as “evidence” , but that’s not quite right either. It is somewhere in between, something like “solid evidence” or, say, “.probably cause to believe”
clues are little bits of evidence but indizi are not prove.
Hmm WHO is based in a French speaking city. I suspect that the tweet may have been thought in say French then mistranlated into English . A very large fraction of postmodern Jargon in English is plain French which has been translated badly (as in proofs for prove or values for Valute (when valute means valuables not values)). Or priviledge for favor (now it’s become English but it was jargon for a while when privileggiare was plain italian).
For many policy purposes, survived but not immune may mostly be treated as immune — because they didn’t die the first time. If nobody was dying of this it would not be the panic that it is.
still at it I note this Italian headline with “prove”
Coronavirus, over 200 thousand dead worldwide. WHO: “No evidence that the healed are immune”
Coronavirus, oltre 200 mila morti nel mondo. L’Oms: “Nessuna prova che guariti siano immuni”
Never, ever presume anything about the immune system. It has had hundreds of millions of years to out think us. While we know that the immune system does produce antibodies to clear the COVID-19 virus, we have no idea of how long any immunity lasts. We have no idea how rapidly it decays if only because the disease is so new. Some diseases like measles confer life long immunity. Others, like the flu are forgotten by the body. This is true for both disease and vaccine induced immunity. In fact, there is a lot of ongoing research on the duration of immunity. See, for example: https://www.sciencemag.org/news/2019/04/how-long-do-vaccines-last-surprising-answers-may-help-protect-people-longer
There are other ways of controlling a disease though. If the number of cases is low enough, new cases can be tracked and isolated. The effects of the disease can be mitigated as they are for AIDS or diabetes, both currently incurable and lacking a vaccine. Practices can be changed to slow the spread as is done for salmonella and other food and water borne diseases. COVID-19 especially hits people living in overcrowded conditions, working in crappy conditions and who don’t have sick days and good medical care. This suggests some obvious mitigation strategies.
It isn’t hopeless. We must just have to make do with fewer billionaires.
The problem with flu vaccines isn’t so much that they are “forgotten by the body” as that the virus evolves so rapidly. This is in part due to the fact that the influenza virus genome is segmented, so not only do new sequence variants emerge, but different combinations of variant fragments can be shuffled in new combinations that evade immune surveillance.
The danger is that these bogus antibody tests are used by businesses and governments to issue “Covid passport”s that allow people to travel and become super spreaders of the disease setting us up for a major resurgence of the disease. The WHO is trying to nip this crap in the bud.
Unfortunately, The WHO managed to further confuse matters by saying that survival of the disease confers “some protection” to the survivor. That implies a benefit without describing the “benefit” in any useful way and actually appears to be pure speculation unsupported by any data.