Base Rate Fallacy on science.org ?
A grim warning from Israel: Vaccination blunts, but does not defeat Delta
11–20 of 102 posts
Re: A grim warning from Israel: Vaccination blunts, but does not defeat Delta
#12I don't think the vaccine is creating a strong memory cell response. The vaccine is probably just ramping up the immune system response for a few months. That alone would prevent death and since we don't really have anything else, it's still better than nothing.
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Re: A grim warning from Israel: Vaccination blunts, but does not defeat Delta
#13I don't think the vaccine is creating a strong memory cell response. The vaccine is probably just ramping up the immune system response for a few months. That alone would prevent death and since we don't really have anything else, it's still better than nothing.
Please don't post conjecture like this that has been categorically shown to be untrue. Vaccines are effective and have been shown to decrease infection and serious illness rates.
Re: A grim warning from Israel: Vaccination blunts, but does not defeat Delta
#14This article never really tackles the fact that p(infected|vaccinated) != p(vaccinated|infected). With high-vaccination rates in Israel, that matters a lot. In fact, the scariest statistic it gives--that nearly 60% of serious hospitalizations are fully vaccinated) gives the p(vaccinated|infected), not p(infected|vaccinated). Trivially, and to make the point, if 100% of people are vaccinated, then 100% of hospitalizat…
p(i|v) = ( p(v|i) * p(i) ) / p(v) p(v|i) = 0.6 p(v) = 0.6 p(i) = ?; but it's high (record case counts) p(i|v) = p(i); high If Israel has a 60% vaccination rate, and 60% of those in the hospital are vaccinated, then doesn't this mean the vaccine has no effect on the chances of being hospitalized?
That is why considering age is important and why interacting variables make it so easy for statistics to mislead when talking to people who are less verse or aren’t aware of the topic being studied.
About 78% of those above 12 are vaccinated in Israel, and the rate is even higher for those more susceptible to the virus.
Without quantifying those factors, it’s going to lead to a garbage in garbage out assessment.
Re: A grim warning from Israel: Vaccination blunts, but does not defeat Delta
#15This article never really tackles the fact that p(infected|vaccinated) != p(vaccinated|infected). With high-vaccination rates in Israel, that matters a lot. In fact, the scariest statistic it gives--that nearly 60% of serious hospitalizations are fully vaccinated) gives the p(vaccinated|infected), not p(infected|vaccinated). Trivially, and to make the point, if 100% of people are vaccinated, then 100% of hospitalizat…
p(i|v) = ( p(v|i) * p(i) ) / p(v) p(v|i) = 0.6 p(v) = 0.6 p(i) = ?; but it's high (record case counts) p(i|v) = p(i); high If Israel has a 60% vaccination rate, and 60% of those in the hospital are vaccinated, then doesn't this mean the vaccine has no effect on the chances of being hospitalized?
Well, the article says 78% of people 12 yo and older are vaccinated in Israel. Not sure what percent if you drop it to include everyone.
87% of those who were hospitalized were 60 or older (which doesn't match the general population). I imagine that vaccination rates are much much higher than 60% among those over 60. In the US its around 80%. But also, hospitalizations are much more likely the older you get. Moreover (and this was the point of the paper the article was discussing), the effectiveness of the vaccine may dwindle with time, and the 60+ crowd were among the first to get vaccinated.
So, no, I don't think you can do so simple a calculation and conclude that.
Instead of back of the envelope estimates, I think I'd just point to this study: https://www.nejm.org/doi/full/10.1056/NEJMoa2108891
Abstract:
Background
The B.1.617.2 (delta) variant of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (Covid-19), has contributed to a surge in cases in India and has now been detected across the globe, including a notable increase in cases in the United Kingdom. The effectiveness of the BNT162b2 and ChAdOx1 nCoV-19 vaccines against this variant has been unclear. Methods
We used a test-negative case–control design to estimate the effectiveness of vaccination against symptomatic disease caused by the delta variant or the predominant strain (B.1.1.7, or alpha variant) over the period that the delta variant began circulating. Variants were identified with the use of sequencing and on the basis of the spike (S) gene status. Data on all symptomatic sequenced cases of Covid-19 in England were used to estimate the proportion of cases with either variant according to the patients’ vaccination status. Results
Effectiveness after one dose of vaccine (BNT162b2 or ChAdOx1 nCoV-19) was notably lower among persons with the delta variant (30.7%; 95% confidence interval [CI], 25.2 to 35.7) than among those with the alpha variant (48.7%; 95% CI, 45.5 to 51.7); the results were similar for both vaccines. With the BNT162b2 vaccine, the effectiveness of two doses was 93.7% (95% CI, 91.6 to 95.3) among persons with the alpha variant and 88.0% (95% CI, 85.3 to 90.1) among those with the delta variant. With the ChAdOx1 nCoV-19 vaccine, the effectiveness of two doses was 74.5% (95% CI, 68.4 to 79.4) among persons with the alpha variant and 67.0% (95% CI, 61.3 to 71.8) among those with the delta variant. Conclusions
Only modest differences in vaccine effectiveness were noted with the delta variant as compared with the alpha variant after the receipt of two vaccine doses. Absolute differences in vaccine effectiveness were more marked after the receipt of the first dose. This finding would support efforts to maximize vaccine uptake with two doses among vulnerable populations. (Funded by Public Health England.)
Re: A grim warning from Israel: Vaccination blunts, but does not defeat Delta
#16This article never really tackles the fact that p(infected|vaccinated) != p(vaccinated|infected). With high-vaccination rates in Israel, that matters a lot. In fact, the scariest statistic it gives--that nearly 60% of serious hospitalizations are fully vaccinated) gives the p(vaccinated|infected), not p(infected|vaccinated). Trivially, and to make the point, if 100% of people are vaccinated, then 100% of hospitalizat…
The calculations running over hospitalization numbers tend to show that vaccines are ~85% effective in preventing hospitalization, usually by showing the reduction in N/100k cases.
That is what I've seen as well.
Re: A grim warning from Israel: Vaccination blunts, but does not defeat Delta
#17At this point it is widely recognized that viral evolution is undermining the effectiveness of the current vaccines at preventing infection (~91% to ~66%) [1] and symptomatic illness (~95% to ~65%) [2].
Still, the benefits of vaccination remain significant - vaccines are helping prevent severe outcomes like hospitalization and death for many people.
Researching formulations that are more robust to viral resistance is already becoming a top priority. Diversifying viral elimination strategies at the population level will also be critical. Mandatory nonpharmaceutical interventions such as lock-downs and masking may help slow the spread of the virus, but at this point those measures will not stop the spread, because SARS-CoV-2 is highly contagious and primarily transmitted through the air (as acknowledged by the WHO and CDC) [3].
[1] Effectiveness of COVID-19 Vaccines in Preventing SARS-CoV-2 Infection Among Frontline Workers Before and During B.1.617.2 (Delta) Variant Predominance — Eight U.S. Locations, December 2020–August 2021 https://www.cdc.gov/mmwr/volumes/70/wr/mm7034e4.htm
[2] Resurgence of SARS-CoV-2 Infection in a Highly Vaccinated Health System Workforce https://www.nejm.org/doi/full/10.1056/NEJMc2112981
[3] Airborne transmission of respiratory viruses https://www.science.org/lookup/doi/10.1126/science.abd9149
Re: A grim warning from Israel: Vaccination blunts, but does not defeat Delta
#18Israel went very heavily with Pfizer which ended up rather ineffective against Delta. With a more balanced mix they would have probably fared better.
Re: A grim warning from Israel: Vaccination blunts, but does not defeat Delta
#19I don't think the vaccine is creating a strong memory cell response. The vaccine is probably just ramping up the immune system response for a few months. That alone would prevent death and since we don't really have anything else, it's still better than nothing.
Please don't post conjecture like this that has been categorically shown to be untrue. Vaccines are effective and have been shown to decrease infection and serious illness rates.
You think you’re fighting misinformation, but GP could be right in terms of T cell response.
Re: A grim warning from Israel: Vaccination blunts, but does not defeat Delta
#20Israel went very heavily with Pfizer which ended up rather ineffective against Delta. With a more balanced mix they would have probably fared better.
> rather ineffective against Delta
I mean, this isn't true... less effective, sure. But it's not ineffective by any measure.