I don’t know, but as I said, she had Covid in August and was already vaccinated. She is negative as of today.
The usual recommendation is that it is effective after 14 days.
However, #3 had vaccine and infection before, so the infection may have “boosted” her immune response even if the second vaccine was too recent to do so.
https://www.covid-datascience.com/post/israeli-data-how-can-efficacy-vs-severe-disease-be-strong-when-60-of-hospitalized-are-vaccinated has this table:
It looks like, in this data set (Israel, Pfizer vaccine), the risk of severe disease for a fully vaccinated person is similar to the risk of severe disease for an unvaccinated person about 25-30 years younger.
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Following up.
Quick recap, last Saturday night, 8 people had dinner at my friend’s house. On Monday, a 23 year old woman at that dinner felt unwell on Sunday and tested positive for covid on Monday.
Husband and wife, 1a and 1b, are both sick and have had positive tests. Husband 1a as of this morning still not feeling better. Neither says they are having any difficulty breathing, luckily. Their 17 year old son is negative so far.
Couple 2 have both had negative PCR tests. Got results back today after a PCR test yesterday.
Both women who previously had covid have tested negative and have no symptoms.
I’ve just done my fourth negative test. I tested Wed morning, Friday morning, Saturday morning, and today, Sunday, at 5 pm.
23 year old woman feels pretty good, if not 100%.
I think couple 1a and 1b got it because the young woman arrived in the afternoon and stayed the night, leaving at about 11 the next morning. They had much more time being exposed to her.
I’m still amazed that neither myself nor the other married couple appear to have got it. We sat at a round table and were equally exposed to her.
I feel like I can rest more easily now, but I want to get my booster asap.
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Looks like the following summary (V = vaccinated, I = prior infection, B = boosted):
| Person | V, I, B? | Exposure | Sick | Test | Notes |
|---|---|---|---|---|---|
| 1a | V | Dinner + Overnight | Yes | + | symptoms day 4, test day 6 |
| 1b | V | Dinner + Overnight | Yes | + | symptoms day 8, test day 6 |
| 1c | ? | Overnight | No | - | 17-year old son of 1a, 1b, test day 8? |
| 2a | V | Dinner | No | - | test day 7 |
| 2b | V | Dinner | No | - | test day 7 |
| 3 | V-I-B | Dinner + Overnight | No | - | booster day -3 or -4, test day 7 |
| 4 | I-V | Dinner | No | - | test day ? |
| 5 | V | Dinner | No | - | test days 4,6,7,8 |
| 6 | V | Index case | Yes | + | symptoms day 1, test day 2 |
Seems like the pattern is not too surprising – only those with the highest exposure (indoor dinner and overnight) got sick or tested positive, except for one who had vaccine, prior infection, and booster who did not get sick or test positive despite the highest exposure.
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You’re hardcore, @ucbalumnus 
.
I think 1c, 17 year old son, had almost no exposure to the index case (23 year old woman). He came home as we left that night and being 17, I doubt he got up until after she was gone. I believe the whole family, 1a, b, c, got tested on Thursday with results back on Friday.
On the whole though, you’ve summarized it very scientifically, except that index case also stayed the night. Also, I am not certain of everyone’s test dates, but couple 2 did at least one home test before the PCR on Friday.
Would anyone like to share any alternative theories as to why it seems that three of us have not tested positive (yet)? I think my theory is right (couple 1a & b had that much more exposure because index case arrived in afternoon and stayed the night.)
I think you are right and have avoided it through having less exposure. As I noted above, in similar circumstances my spouse got it from hugging our nephew, but I didn’t hug him and wasn’t infected.
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Cross-reactive immunity is the first thing I think of for questions like yours - each of you walked into the pandemic with a different Covid immunity starting point: Prior exposure to common cold coronaviruses enhances immune response to SARS-CoV-2 -- ScienceDaily
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I was deathly ill from some virus as a toddler in Thailand. Apparently my doctor told my parents that I would probably end up much healthier than average because of that. (Not to mention that I spent most of the rest of my childhood in East Africa and other part of Asia.) It may have been the power of suggestion, but it is true that I am very rarely sick. I’d like to think it will help keep me safe from Covid - along with vaccines and being pretty careful.
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Fascinating! Do you know what illness it was?
Also, @ucbalumnus , the 17 year old was vaccinated in May. I do think it’s going to be really hard for him to avoid getting it.
I am wondering… maybe the 23 year old didn’t have Delta. Maybe she had some less contagious variant? I have no idea how many variants are going around right now.
@smiles2122 , also very interesting. Wonder if people who have been less prone to colds when younger are more susceptible.
I doubt it. Most 17 year old boys don’t hug their parents regularly or spend their days in close proximity. Are the parents isolating or behaving normally in the house? Do they share a bathroom?
In the case of our nephew (who didn’t isolate in the house), his mother eventually got COVID, but his father never did.
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When D had shingles as a young preteen, I cared for her and she didn’t isolate and I never got it. When H got shingles years later, he never gave it to anyone else tho he didn’t isolate either. I know, different viruses but infections and resistance can vary considerably.
Exposure to someone’s shingles may pose a risk of getting chicken pox if one is has not already had chicken pox or the vaccine for it.
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If it were a less contagious variant, #6 may not have brought the unwanted guest to the party to begin with, or #1a and #1b may not have gotten sick from her.
My husband had Covid and I never caught it (prior to vaccines, probably a less contagious variant…but still). I spent months trying to figure out why. At one point there were blood theories floating around (O+ was “better” for some reason), but my H is O+ and I am AB+.
I read an article about kids- one theory was that all of the immunizations that they receive (particularly MMR) help protect against Covid (pre Delta when their cases were fewer) I don’t know how true that really is, but I did coincidently receive another MMR vaccine for work when I was in my 30’s (didn’t feel like testing my antibodies and they said it would be fine to receive the shot).
Even now at my school…kids are getting Covid, vaccinated teachers and staff are getting it…and others are not. I am not sure yet where all these cases are being transmitted (school? home?).
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My nine-week-old son was admitted to the hospital the same day my husband was diagnosed with shingles. We had a three-year-old at home.
The hospital wouldn’t let DH visit our son because he was contagious with the chicken pox virus. Ugh. DH had been laid off the week our son was born and still hadn’t found work. That was one of the tougher weeks of my life.
Another story about the whims of viruses though not Sars- coV-2/Covid 19 but does show the vagaries of virus transmission.
I give blood often and just gave last week. The person taking my blood asked if I knew I was CMV negative. I had no idea what that was. I learned that CMV/Citomelagovirus is a very common virus more than 50% of US adults get by the age of 40. Most never even know they had it as it is very mild. It is, however, dangerous to newborns, so all blood is tested to make sure they only receive CMV-negative blood. CMV negative blood is processed differently and packaged in very small amounts so that should a baby need a transfusion it is safe and they will receive blood only from one donor.
I’m hoping that as you age you have less of a chance of getting the virus and so can remain a negative donor.
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You’re right. The 17 year old is totally downstairs and the parents are upstairs.
He’s getting tested again today.
Well I think there are good theories already (levels of prior exposure/cross-reactive immunity; the overnight provided more continual accumulating exposure, etc). But maybe it’s a timing thing related to the overnight. Not that the other people who slept in the house had more hours of exposure to the index case, but maybe the index case wasn’t highly contagious until the next morning at breakfast. Perhaps at dinner she had a low viral load. My understanding is that vaccinated people are contagious for briefer periods of time. You who are negative may not have been near her when she was fleetingly contagious. Just another possibility.
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You can’t give shingles to anyone else.
A person with shingles can give Chicken pox to someone who has never had it, but only if they make direct contact to the fluid from the shingles rash. Chicken pox is spread person to person much more easily (airborne and direct contact with sores) than shingles spreads chicken pox.
Hopefully I explained that in a way that makes sense.
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