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Vaccine effectiveness in "real world"
Did you mean "they go undetected because they are asymptomatic"?

Good to see the separate numbers. 0.5/(7.0) corresponds to a 93% vaccine effectiveness, which is the right ballpark.
I was also glad to see the announcement/claims that J&J shot confers meaningful protection against Delta variant.
M_T, what a difference a letter makes. Yes, asymtomatic, not symptomatic. I expect that vaccinated people have asymtomatic infections that don't get reported.  I need a personal editor before posting. 

I agree that the vax/unvax rates are consistent with the CDC study of health workers that were tested weekly with PCR tests:


In the UK they report average numbers that hide that mRNA is more effective than the vector vaccine (AZ ) by providing average figures. That makes sense in terms of public health in a world were supply of the mRNA vaccine is limited. One does not want people to wait to get the "better" vaccine. The reported rates of infection in Contra Costa County (CCC) may be lower than the actual infections because they are reporting infections by the system that CCC uses, not weekly PCR tests in a careful study. This is true for all people. The numbers quoted in the CDC study  do not apply for J&J, some indications are that it is not as "good." That doesn't mean that serious outcomes are more common, we just don't know. I note that a fraction of the folks in the CCC numbers learned of their infection after they were admitted to the hospital for a different reason. Any mortality analysis for vaccinated folks is now complicated that these people were sick enough to be admitted. To me, it's an unresolved issue. How much "better" are the mRNA vaccines. What is "better" anyway. I don't care about PCR positivity, I care about damage to my body. Wait, I care about spreading the disease to others. Crazy rant her to acknowledge that trades in risk of side effects, effectiveness, risk of serious outcomes, risk of infection, and risk of spreading are so complex that I can't handle it rationally.

The CCC data was able to reach me on an emotional level better than the CDC study above. I knew the numbers, but it reminded me that people do get infected after vaccinations. I do not, however, know what level of paranoia to engage in with respect to my personal health. My family is vaccinated, so I do not risk them. My age and prior respiratory issues can't be used to compute a number due to unknowns. The low rates in the Bay Area do seem to indicate that exposure is less likely these days. 

I don't lay awake at nights thinking about this. I just try to behave reasonably and do the risky things that bring me the most benefit but not some other things. Do you folks feel you have a handle on these issues?
We all work with what our risk perceptions, risk tolerance, and tolerance for non-pharmaceutical interventions are.

I think I reported here that a Stanford MD's husband was washing groceries in May.  I still wash (or remove an outer box) for frozen and/or fresh food.   I am wearing my mask in public though I am fully vaccinated and live in a county where the infection rate is (by US standards) low-ish.  I leave or am only reluctantly shopping where the clerks are not wearing masks, even if the Governor says they aren't required.  (Has he done away with the pretense that the Health Officer calls the shots for medical issues?)  

(By the way, all the staff at the Fish Market in Palo Alto and Armadillo Willy's in Los Altos had masks on when I went to pick up food in the last week.)

On the other hand, my unvaccinated (too young), once-infected grandchildren were taken to Disneyland Saturday by their father.  (Sigh.)
ran across this today
The paper that news article talks about is Attenuation of antibody titres during 3-6 months after the second dose of the BNT162b2 vaccine depends on sex, with age and smoking as risk factors for lower antibody titres at 6 months.

Basically, a study in Japan of a few hundred people has been conducted, where they took their antibody titers shortly after their second Pfizer shot, then at 3 months, and now at 6 months.

This should probably be read in context of their Age and Smoking Predict Antibody Titres at 3 Months after the Second Dose of the BNT162b2 COVID-19 Vaccine.

At 3 months, they found that older age correlated to a decrease in anti-body titers.  They found that ever-smoking (vs never smoking) was the only significant differing factor. Ever-smoking was associated with a decrease in titers.  While a gender difference was noted, it was explained by a different rate of smoking in the two genders.  Adjusted for smoking, gender was not significantly associated with a change in titers (within an age group).  Because of the smoking difference, women had higher titers than men.

However, in the 3-6 month time frame, the women's titers dropped faster than the men's.  Indeed, neither age nor smoking was a significant factor this time, only gender.

Mentioned in the paper were factors associated (in other studies) with differences in titers immediately after the 2nd Pfizer dose.
Quote:Various factors, including older age, male sex, ethnicity, social condition, obesity, smoking habit, drinking habit, hypertension, cancer, and use of immunosuppressive drugs, have been reported to reduce the Ab titres obtained shortly after the second dose of the BNT162b2 vaccine. In Japan, older age, male sex, and drinking habit are reported risk factors for a lower peak value of the Ab titre.

probably behind a paywall for many.   Talks about a couple of studies comparing immunity from vaccines versus prior infection that have opposite conclusions--I believe neither has been peer reviewed.   Also hits on stronger memory B cell response over the long term from infection versus vaccine.   And also concludes that strongest immunity comes from combination of vaccination and infection.

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