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Australia should be moving to utilise people who have recovered from coronavirus and developed immunity against the virus to bolster essential services, a leading expert says
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- Title
- 'Very useful resource': How Australia could utilise people with coronavirus immunity
- Authors
- Michael Fowler
- Published
- Apr 5 2020
- Word count
- 587 words
I've read conflicting reports and messages about whether recovery makes you immune. There's so much mis-information.
The clash is between "Of course you are immune after recovering, same as every other virus" and "it's unknown".
Can anyone knowledgable clarify?
I'm not a medical professional, but I have read a lot about the coronavirus (possibly too much).
Your body's immune system will generate antibodies when it encounters this coronavirus - just like it generates antibodies for all other viruses. That's why you can't (generally) catch diseases like measles or the mumps twice: after the first time, your immune system has a template for antibodies to those viruses, ready to fire up the instant it sees them again (the template is stored in so-called "memory B-cells").
You even have perpetual immunity for the influenza virus after you recover from it. The problem is that there is no "the" influenza virus: there's an ever-growing variety of influenza viruses, plural, as each virus mutates and spawns different versions of itself. Each season's flu is therefore slightly different than last season's flu, which is why your antibodies to last year's flu probably won't work this year, which is why you need to get this year's vaccine.
The default assumption is that the coronavirus, like all other viruses, will prompt your body to create antibodies to fight it off - so, once you've had it once, you can't have it again. And, generally speaking, the evidence so far (it has only been a few months!) seems to support this hypothesis: people who have had the SARS CoV-19 coronavirus are mostly not getting it again. This implies that the antibody assumption is holding true.
There are a few occasional reports of people catching the coronavirus a second time, but it's not yet known exactly why this is happening. Scientists haven't found enough examples of this to be able to study the phenomenon. So, it's not known exactly why this might be happening. There are a few possibilities:
The person catching the coronavirus a second time didn't really have it the first time. Maybe the original test gave a false positive to the SARS CoV-19 virus, when it was actually something else.
The person catching the coronavirus a second time is actually catching a different coronavirus for the first time. Maybe the coronavirus is mutating so quickly that there are already new varieties out there.
The person catching the coronavirus a second time has already lost the antibodies for the coronavirus. While many antibodies stay with you for life, some expire over time. The memory B-cells that store the template for a particular antibody can die off if they're never used. If you're never exposed to a particular virus, you might find that, ten or twenty years later, you no longer have immunity. However, templates expiring within only a few months would be extremely unusual.
So, until scientists can explain exactly why a few people seem to be catching the coronavirus a second time, they're not willing to commit to the statement that "of course you'll be immune after recovering". Scientists are not known for making absolute statements. They'll always hedge their bets.
Another explanation I've heard for the small number of patients who got re-infected is that they might never recovered to begin with. The tests that showed them no longer having the virus could have returned a false negative.
Thanks, your reply makes a lot of sense, especially the part about the memory cells. I also read that first SARS outbreak people developed immunity that lasted under a year and then "losing" it and sadly research/vaccine development (which may well have been valuable now) halted once the outbreak died out.
I've seen a few scientists saying a similar thing about this coronavirus: the immunity that people get from exposure will only last a year or so.
But a year is a long time in pandemic terms! That can get us through until a vaccine is ready.
We don't have a vaccine against SARS or MERS, and it may be tricky to get a working vaccine for SARS-CoV-2
Oh, well. In that case, we might as well just not wait for a vaccine that's not coming. Let's unlock this lockdown, get back to work, and build up our herd immunity right now. We can all follow the lead of Italy, Spain, and the USA.
If the immunity is degrading due to mutation the vaccine will degrade just as quickly.
If I'm not mistaken that depends entirely on if we manage to vaccinate lots of people quickly. How is it supposed to mutate if we vaccinate all possible patients? If 80% of a population is immune, the vaccine can't skip from one to the other indefinitely for a year, so it doesn't have the time to mutate.
Mutation in the usual suspects (cold, flu) happens precisely because they're so mild we don't fight them with enough vigor. We just suffer through them and spread them. If everyone were to get their flu shots for a few years in a row, I'm sure we'd see a decrease in the number of strains out there quickly and we could then hope to eradicate it.
Of course, that doesn't help if some countries won't vaccinate enough and then start breeding immune strains. But with how big a deal corona is, I'd wager we're going to see almost-universal vaccination.
That level of vaccination simply isn't possible. If it was, we really would have eliminated influenza.
There are people who can't be vaccinated at all, and people who the vaccine won't do anything for. A vaccine can't be manufactured and delivered at an appropriate rate even at the best of times, and it can't be injected unless you're really sure the person doesn't already have the virus, else it will make things worse (potentially much worse i.e. dead).
That is before you even get to antivax individuals and countries.
Well, you don't nearly need complete coverage. With our current estimates of a R0 of 2.5 or more likely 2, you need a bit more than 50% coverage to stop the epidemic. Certainly doable for industrialized countries and with some help from the WHO, probably even in large parts of the developing world.
Never mind that we think SARS-CoV2 mutates a lot more slowly than flu and cold viruses. And even a immunity for a similar virus helps fight the disease. Going to have to wait and see, but I'm not too concerned about the possibility of the vaccine being a dud yet.
This the basis for everything I'm saying. If this is true then both points you've made are invalidated. If it isn't true then it isn't necessary in the first place.
My point is that degradation of immunity doesn't matter if we can bring the hammer down hard enough to make it go away. If immunity lasts a year, that means we have to eradicate it within a year and then it doesn't matter if it would mutate because it can't mutate if it's dead.
Both of my points were meant to show that eradication wouldn't be ridiculously hard. 50% coverage isn't a lot, the WHO will lead the way in the developing world. And what unvaccinated clusters remain will or will not go through the disease, either staying protected or developing immunity.
The point about mutation being slow served to illustrate that we might have a lot more than just a year, but we're not sure just how much.
Combine all of that and we can reasonably expect to have more than a year of immunity because the disease mutates more slowly in a more limited pool of hosts - which it will have once we get the vaccine.
All this to say: Currently, we expect immunity to last 1-2 years (not sure though), because we think the virus might mutate. If a lot less people get sick, a lot less mutation occurs and we can stretch those 1-2 years.
In that case, we'll probably see people getting vaccinated for SARS CoV-19 every year, just like they do for influenza.
You can apply my statement to whatever period is implied by "If the immunity is degrading due to mutation the vaccine will degrade just as quickly."