In a nutshell, you can't catch it again right away after having recovered.
"Can't" is too extreme. "Very unlikely" is much more accurate.
So basically only first time you will experience more serious symptoms like a fever, the subsequent infections would be trivial common cold.
We'll see.
They just got very ill again in the last week and tested positive again. Might be totally a-typical or it could just be that we've not seen that many people actually have the chance to catch it twice yet.
Ah! I knew that this was true for the flu, but I always thought there was just a single Common Cold that you could get over and over again. Thanks!
A new coronavirus jumps from an animal to humans. No human body has seen this type of virus before, so when it infects the immune system has to work a lot to learn how to fight it. This causes symptoms like a fever which is a sign of the ongoing struggle. For frail people it means the immune system is not strong enough to counteract the infection and it spreads and potentially kills them.
However, if the immune system learns quickly enough how to fight it, antibodies are killing the virus faster than it can multiply and you get better. The antibodies then disappear in a few months but the long term memory cells remain.
Later, the virus infects you again. You develop the symptoms of a light respiratory infection but the immune system quickly references the memory cells and is able to produce suitable antibodies really fast. The fight is short and easy, the antibodies defeat the virus before it has time to spread. There is no sign of the struggle like first time (no fever) but only the light symptoms we don't even think of (common cold).
Now, how about children? Well as we see already they're unlikely to be seriously affected (low mortality). And children get lots of fevers (parents can confirm). So probably sometimes in the early years we get infected by some coronaviruses our bodies have never seen, the immune system puts up an intense fight and builds the long-term immunity that will be with us as adults.
For SARS-CoV2 and the COVID-19 disease it causes this means that even without the - quite likely - availability of a vaccine over time natural immunity will build up within individuals and the population as a whole, which has the potential of both making the resulting disease less severe and future waves spreading less.
If most individuals who contract the virus during the next few months can't get sick anymore and can't spread the virus anymore for the about 6 months those individuals are taken out of the equation, which leaves less individuals for the virus to spread to in the next wave.
If that's the case, out of curiousity why there has been numerous reported cases of people that catched covid again after already recovering from it?
Edit: So... after reading the article I'm not sure this is the case for all people as this research has been done only on a group of asymptomatic & low/mild response people. IMHO for a sentence like that to be valid, it should be demonstrated on the other part of the population, those that have a high immune response against the virus and end up in a critical state from it.
There have been many, many news articles that speculate about this, but to date, I'm aware of two papers that document re-infections. Both papers isolated and sequenced the viruses involved, and both papers documented re-infection with significantly mutated variants of the same virus.
But which of those will be by majority the study just didn’t investigate.
In immunology no answer is “yes” or “no” but the range. The range is different between different people, and we can conclude what the typical ranges are, if there’s enough data collected. But the ranges are still unknown at the moment.
The same reason (a need to find the ranges) is why you can’t make a vaccine candidate and be sure how it will work, unless you run big and long enough trials. And that’s why that takes time.
Here’s what this study figured out, quoting from the article: “The size of T cell response differed between individuals, being considerably (50%) higher in people who had experienced symptomatic disease at the time of infection six months previously. Further research will be needed to determine the significance of this finding.”
As you see, again some range, but also not concluding what you claim.
The open question is, again, what will be the percentage of such cases.
I don't doubt that reinfection will be rare, at least over the span of a few months, but to my mind that would seem unproven given how hard we're (generally) working to keep people from being infected in the first place.
'Quite high' could mean anything, but if you're implying 'higher than' then that isn't supported by the statistics I've seen in a dozen countries.
No. From the current papers, we just know that the reinfection where people have had their virus sequenced in both first and second infection is very rare.
The problem is technological. Up to now there are around 50 million confirmed cases in the world but probably less than 100 thousand sequencings performed, and only a few sequencings by those who had strong enough symptoms twice and had the chance to have sequencing twice.
Without sequencing one just can’t prove that some case is an actual reinfection. All other cases are just “possible” (i.e. unprovable) reinfections and nobody can claim anything worthy of a scientific paper about them.
There were some suggestions that Covid-19 would be an exception to this somehow, and having recovered, you would still be just as susceptible to getting it again. Which, if it had been true, would have been really bad news, although I suppose it would also have meant there was no reason to wait for a vaccine, because if even the actual virus itself doesn't teach your immune system to look out for it, then there's no way a vaccine could.
But, it's good scientific/medical work to verify that it works like most other viruses, and people who have recovered, are at least almost always going to be resistant thereafter (for at least six months, because that's all the time that has passed yet, although evidence from SARS suggests 10 years or more).
I wouldn't say that completely follows. It would certainly indicate that developing a vaccine would be harder, but not impossible.
Modern vaccine development is essentially fly fishing at this point: the amount of control and options we have with the immune response-generating stimuli exceeds naturally-ocurring scenarios.
As an example, most of the spike-protein-expressing vaccines generate / deliver modified spike proteins, distinct from those found on actual SARS-CoV-2 coronavirus.
It's triggering your immune system to produce and/or store things, the presence of which then confers resistance when subsequently exposed to the actual pathogen.
So from that perspective, the next question is, "Do naturally occurring pathogens, presented in a natural manner, produce an optimal triggering themselves?" To which the answer, as you might guess from the messiness of real-world biology, is "No."
It turns out that while amazing our immune systems are also general purpose and adaptable, and such systems can get confused, or go off on a tangent, or focus on the wrong thing, etc etc.
Vaccines interact with this system by balancing two things: (1) how do I trigger the strongest, purest immune response that's effective on the thing I want to immunize against & (2) how do I avoid triggering such a strong immune response that I convince the body to attack itself?
It turns out, with modern biology, we actually can do better than nature on (1). Even if (2) still requires some guesswork (and a lot of testing).
This is bad news because it means that herd-immunity is not naturally achivable. It means you most get a vaccine at regular intervals to be protected against this strain of the virus.
It also means that lockdown is best strategy to reduce strain on health services until vaccine is ready and freely distributed to all.
Replicated studies have already found that prior exposure to other coronavirus infections (common cold, animal viruses) leaves behind t-cells that are activates for covid-19, as long as 17 years. And that a large percentage of the population has these t-cells. [0]
Does this change your opinion on herd immunity?
It's a shame that the news emphasizes pessimistic headlines and anecdotes over science.
Not much scares me in this life. But just saw my first COVID reinfection this full moon Halloween & I am fucking shook.
20-something yo w/ massive PE, coded, TPA, ECMO in ED, hemorrhage, 3 code carts, methylene blue, PRBCs.
Praying for them and their family And for all of us. https://t.co/T0YqmVxLx8
The language is literally fear mongering. It's not an objective anecdote.
Reinfected! and the reinfection becoming a bad case! No immunity... Article hints that you can expect to be relatively protected for up to 6mo after infection.. But there are no guarantees.
From the article: "There is still a lot for us learn before we have a full understanding of how immunity to COVID-19 works. (..) we all should still follow Government guidelines on social distancing to ensure we play our part in minimising the spread of COVID-19 within our communities." -Professor Paul Moss