Chao, how is your friend and his family doing now?
I don’t think so. There are too many variables. Just extrapolating from a personal experience, when I was young, my mom had me play with kids with chicken pox so I would get it early. I didn’t get it. I wasn’t immune. I got it as an adult. I don’t know why I didn’t get it when I was young with multiple exposures, but it didn’t mean I was immune.
Just looking at people who don’t get it doesn’t give enough of an indication. There has to be some testing or screening to determine why people don’t get it. That doesn’t exist yet, so just observation isn’t going to give quantifiable results.
To date (I just spoke with him last week) he is doing very well. Seems to be completely back to normal which is wonderful as he went into this with some preexisting health issues. (Obesity, high blood pressure, pre-diabetic)
His wife who is on disability due to extreme health issues still has not shown any symptoms of Covid-19 and his daughters are great as well. In fact, his one daughter is 3-1/2 months pregnant and feeling grand.
I had two smallpox shots when I was a kid and neither one of them made a mark on my arm. They weren’t going to let me into kindergarten until we got a note from the doctor surmising that I was naturally immune. I had the flu in 1957 when I was 5 years old and have not had it since. I do not get a flu shot.
I am now 67 and my attitude is, if I get it, I get it. I’ve lived a good life and we all are going sometime.
Well, we will miss you and a significant fraction of the people you interact with in your daily life.
There is an alternate explanation, which is getting a lot of consideration: Some people just seem to be capable of infecting a lot of other people. If the infected people you know doesn’t include one of those “super-spreaders”, then you probably won’t catch the disease.
If, a lot of the time, you are exposed to a lot of people who are infected, then “probably won’t catch the disease from them” won’t protect you. In an epidemic situation, even lots of small chances of catching disease adds up. But some of the outbreaks are explosive.
They are trying to put numbers on this, by comparing the number of explosive outbreaks to numbers of single cases. C19 may be somewhere in the middle compared to other diseases. AFAIK there aren’t any good explanations for this.
Interesting question. I do know that with HIV, there is a small subset of people called “elite controllers” who are HIV-positive, but asymptomatic with an undetectable viral load. However, and it’s a big however, being an EC doesn’t mean you’ll live forever. The last hypothesis I saw was that ECs’ immune systems were running all-out to keep a lid on HIV, but eventually, it burns out, so to speak, and the person develops something fairly rapidly fatal like incurable non-hodgkins lymphoma.
Whether experiences with retroviruses like HIV can be directly correlated to a coronavirus remains to be seen.
From the BBC: The people with hidden immunity against Covid-19
Several studies have shown that people infected with Covid-19 tend to have T cells that can target the virus, regardless of whether they have experienced symptoms. So far, so normal. But scientists have also recently discovered that some people can test negative for antibodies against Covid-19 and positive for T cells that can identify the virus. This has led to suspicions that some level of immunity against the disease might be twice as common as was previously thought.
Most bizarrely of all, when researchers tested blood samples taken years before the pandemic started, they found T cells which were specifically tailored to detect proteins on the surface of Covid-19. This suggests that some people already had a pre-existing degree of resistance against the virus before it ever infected a human. And it appears to be surprisingly prevalent: 40-60% of unexposed individuals had these cells.
Yeah, the simplest explanation seems to be that not everyone’s immune system was as ‘naive’ to the germ as it was made out to be.
Or maybe covid-19 has been around and infecting people longer than we thought, only mutating enough to kill recently. How else could it have gotten in those Spanish sewer samples taken 16 months ago?
The SARS-CoV-2 virus seems to lock onto the angiotensin converting enzyme 2 (ACE2) complex. It is entirely reasonable to hypothesize that some people may have genetic variants of the ACE2 complex that the virus simply cannot attach to which could make such persons effectively immune from infection. The second linked study correlated several variants of that gene with differing patient outcomes.
A more recent article on this, basically showing the same thing.
We had a disagreement about the meaning of the word “DNA” in another thread, but the important take away is the PCR amplifies fragments of DNA, not whole DNA. You will get a PCR match if the fragments you test for match.
For this reason, PCR tests are for fragments which are known to be informative. But if you test enough things, you will always get a false PCR result, and the false PCR result will likely be something closely related. Unless there is a problem with the test, those numbers are so small that they don’t matter. Really don’t matter, as in “test everyone in the country”. But if there really is a problem with the test – say, it wasn’t verified against COVID strains found in Spanish sewerage – then it doesn’t mean anything.
Would you mind saying a little more about this? I’m not entirely sure I’m completely following you. Specifically, what I’m wondering about is this. If there is a significant enough ‘false positive’ rate for these PCR tests – meaning, let’s say in this case, that it implies spread of virus where the virus hasn’t spread – than any country that ramps its testing up to very high levels is always going to ‘see’ some prevalence of spread even if the virus were to die out, correct?
Since it depends on a fragment match to the test, a different PCR test will not show positive – it can be checked in a research lab. If there is an important error, a new PCR test can be developed.
Also, the false positives for PCR testing are dependent on true matches – it won’t look like “prevalence of spread” unless there is a disease that is prevalent and spreading.
At some level, the question if two viruses are ‘the same disease’ has now become a semantic question. COV is COV even though there a multiple types. COVID-19 is COVID-19 even though there are multiple subtypes, and Dengue is Dengue even though there are multiple serotypes, but cowpox and smallpox are different even though there is only one serotype.