My wife is a doctor and just got her 2nd dose of Pfizer today, so 7 days from now she's supposed to be protected. Except that the experts say we don't really know, so she should continue to wear a mask and SD just like she's done until now. And even though she should be safe from getting sick, she could still asymptomatically infect everyone else. What a great yeshua this vaccine is!
Could someone please explain the science and the l'maaseh of what - if anything - changes at this point and becomes safe?
I avoided answering this last week because I figured the question was important enough that some competent journalist would soon do a better job than me. And they have:
Families with one person vaccinated (health worker, elderly) still taking precautions
https://www.nytimes.com/2020/12/26/health/covid-vaccine-health-workers-families.htmlhttps://www.cnn.com/2021/01/10/health/grandparents-visits-covid-19-vaccine-wellnesss/index.htmlGood summary of post-pandemic advice. Before/after vaccination isn't like a light switch, that's turned on and suddenly we're back to normal, but more like a sliding dimmer switch, that we gradually get closer to normal.
https://www.nytimes.com/2020/12/21/upshot/after-vaccine-recommendations-experts.htmlPrevious article references the survey that asked epidemiologists how they themselves would change their behavior after vaccination. Would be interesting to hear from them again after they've actually been vaccinated.
https://www.nytimes.com/2020/12/04/upshot/epidemiologists-virus-survey-.htmlIs it appropriate to test for antibodies, and then base decisions on the results?
The sources I've seen say No. There's a lot of variability in how much Ab individuals produce, and there's no known threshold that we can say below this number you're at risk. It's likely that Ab numbers can get quite low and the person would still be immune because of the memory B cells and T cells that are quickly activated if re-exposed to corona.
And can someone explain to me why a post-vaccinated person who's supposed to have even more antibodies is different than someone who recovered from COVID who's generally considered to be safe for at least 90 days? Why don't people worry about the latter being a silent spreader but perhaps the former is riskier?
Like Dan said above, there just hasn't been enough time to study whether immunity is different in those infected or vaccinated. On the one hand, those vaccinated produce more antibodies than those naturally infected, so we could expect their immunity to be stronger and longer lasting.
On the other hand, those naturally infected produce a variety of antibodies. IIRC a paper last spring reported something like 80 or 85% of antibodies are to the Spike protein, and the remaining antibodies were to the N protein and one or two others on the virus surface. Since the anti-spike proteins were most prevalent, and the spike protein was found to be the means by which virus enters the cell, that was the one chosen for the vaccine, but that paper suggested that perhaps for optimal immunity, the vaccine should include a range of antibodies that mimics the natural situation.
Another difference might be in whether the vaccine is like the natural infection in activating T cell responses in addition to antibody production.
There also might be a difference in production of different antibody classes. IgM is the first quickly produced antibody, and IgG, which takes a bit longer to make, is the most important for fighting infection. But there's another class, IgA, which is released in secretions, such as saliva and mucus secretions in the nasal passages, where they can neutralize the virus before it even enters the body. If the vaccine is less effective at stimulating IgA, then a person might make enough IgG to circulate in their blood and not get sick themselves, but the virus might thrive in their mouth and nasal passages, and so could be expelled while speaking or coughing and infect others.
AFAIK there's no evidence yet that vaccine immunity differs from naturally acquired immunity in strength or longevity, but precautions are still recommended because of this uncertainty. Also perhaps because those being immunized first are at especially high risk, either because of their age or their proximity to infected patients.