Kathryn writes:
Greetings TWiV! I’m a dentist, and fully vaccinated with Moderna since January 2021. I recently developed a headache, sore throat, and slight congestion. On day 2 of symptoms I decided to take an “at home” rapid antigen test before going to work. My home test showed up with a clearly visible, but not strong positive result. I took a second test in an attempt to confirm the result, which showed a very faint second line. I took a third test, which showed negative. All 3 tests were taken within 2 hours of each other. I canceled my patients for the day and was able to get a PCR test that afternoon at a site that could provide results while I waited. I was shocked when my PCR test came back negative. I was told I could trust the PCR results.
My question is, what is the shortest amount of time someone could have a COVID infection that’s strong enough to produce a positive test result? Is it possible someone could only test positive for a day or two before their immune system clears the virus? Thanks for your thoughts.
– Kathryn
PS: I thought I would also share that I live in northern Michigan, and the nearest site that could give me same-day PCR results was 1.5 hours away. It was worth it to me to drive that distance to avoid all the personal hassle of waiting 4 days (the norm in this area), not knowing if my 2 young unvaccinated (ineligible) children were at risk, or needing to quarantine them unnecessarily, and having to cancel days of patients while I waited for results. This still seems a travesty to me that timely PCR results are still that difficult to access. Appreciate your show. Thanks for your discussions and insight!
Helen writes:
Hi,
I listen to your shows all the time and really enjoy them. Microbe TV performs a great public service.
I thought you might like to hear about my dad, and I have some questions about COVID.
My father is 97 years old, has no chronic health conditions, walks a mile every day and lives alone in Mississippi. He got his second Moderna vaccination for COVID February 25. Prior to getting his third vaccination, his doctor required him to get his antibodies tested which he did on Aug 31. The test result was “0”. I am not sure what they tested, but he was told he could get his third shot and he got it on Sept 3.
On October 19 he got his antibodies tested at his doctors office and the result was “55.” The technician told my father this was a “good” result.
My father is now thinking that he may have a “shield” against Covid and he should be safe to start socializing more, going to church, supper club, Lions Club, and the YMCA – activities that he has not been able to enjoy for over a year. He is not very happy about wearing his face mask but he does when he occasionally has to go someplace like the drug store. I am not sure how much he would wear it when he socializes.
So my questions are: What should I think about all this? Can you help me understand the result of 55 – sorry I don’t have more information about the test. (My father is of the generation that felt like asking a doctor too many questions might insult them by questioning their competence.) What is the usual duration of antibodies? Or what could be expected for someone his age? How long of a window of time might it be relatively safe for him to socialize more? Or do antibodies have anything to do with this?
I am not an immunologist or a virologist and would really appreciate it if you could take a few minutes to explain a bit about how the immune system works—I hear you saying that antibodies are not the whole story and there is other immunity such as memory-B cells (?). I would love to see you draw a picture to explain a little about all these cells. If memory cells are important, would it be helpful for them to be measured?
I know I have rambled on a lot, but I would love to hear your feedback about my dad’s situation.
By the way I am in North Carolina where the weather is getting cool at night and my cherry tomato plants are still making flowers which I am hoping will have time before frost to develop into fruit.
Thanks for your response,
Helen
Charles writes:
Hello TWiVers;
A great day in NC. 71F, 22C, low humidity and just a few clouds. If it was like this all year round central NC would have a population of around 100,000,000.
During TWiV 818 part of the discussion made me want to ask what traits good scientists share. Praying to Google brought up a bunch of good traits, but missed a couple of very important points.
First, good scientists have to have almost no fear of being wrong. Not that scientists want to be wrong, but that their egos don’t take a devastating hit when they are wrong and they see it as an opportunity. A scientist that is never wrong has never been right about anything that is important or is very young.
Second, most of the lists of traits talked about failed experiments, without knowing what a failed experiment is. To the layperson a failed experiment is one that did not turn out how the scientist wanted or had predicted. In reality a failed experiment is one that failed to answer the question, not one that failed to give the expected answer. Here is an example of a failed experiment of which I have first hand knowledge. After hours of set up and preliminary data collection, a frequency generator was set to 60 Hz, not 60 cycles per minute. Bad stuff happened. To make matters worse, we looked in the wrong place for the problem. So it happened again. After the second failure we did find the problem and added a second check of the frequency generator to the procedures for the experiment. At about $10,000 per run, those were expensive mistakes.
Thanks,
Charles
PS, is Tom Lehrer going to be anybody’s pick?
Daina writes:
Just in case you did not notice, Merck published a response (and the authors followed with a response to Merck) to the Zhou, et al., paper on genetic toxicity in mammalian cell culture with the molnupiravir metabolite (TWiV 818 paper).
Thanks for all the TWiVs, Immunes, TWiPs, and TWiMs!
Daina
Daina sent https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiab362/6319402 and https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiab363/6320086