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Comment by rossdavidh | Hacker News Reader

"The study, published in The New England Journal of Medicine on 28 July, draws on data from almost 11,500 fully vaccinated health-care workers...testing between late January and late April 2021 identified 39 workers who had become infected with SARS-CoV-2 despite being fully vaccinated. All had mild symptoms or none at all..."

TL;DR the Pfizer vaccine works, essentially 100% of the time as far as severe cases go, more than 99% never getting it at all. I'm glad they're doing the rest of this research, but this part is what I personally am most concerned with.

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"Two doses of the Pfizer/BioNTech or Oxford/AstraZeneca vaccine are estimated to be 96% and 92% effective against hospitalisation with the Delta variant, respectively

Vaccine effectiveness against symptomatic cases with the Delta variant is estimated to be 88% after both doses of the Pfizer/BioNTech vaccine and 67% after both doses of the Oxford/AstraZeneca vaccine."

Source:

https://www.ons.gov.uk/peoplepopulationandcommunity/healthan...

"A full course of the Pfizer-BioNTech vaccine is 64% effective at preventing symptomatic Covid-19, according to an early study by Israel’s health ministry reported Monday, much lower than previous estimates of nearly 90%.

The vaccine still appears to be highly effective, 93%, at preventing serious illness and hospitalization, the data shows, though this is also slightly lower than earlier studies suggested and for other variants."

Source: https://www.forbes.com/sites/roberthart/2021/07/06/pfizer-sh...

Also important and useful, but that's a different percentage. That's the percentage reduction as compared to a non-vaccinated (hopefully otherwise matched) group. This is the percentage of the population (here, healthcare workers) who got it. Which, frankly, is the percentage I care more about, personally, although for Phase 3 testing of vaccines of course the percentage you're talking about is what matters.

Given that my daughter, who got the Pfizer vaccine, is unlikely to be exposed to covid-19 virus MORE often than a typical healthcare worker, this is good news. I wish we had as good a study for Moderna and J&J, but hopefully we get one soon.

There wasn't a set of unvaccinated health care workers as a control so the science doesn't prove that TLDR. The fact that there was no severe symptoms is encouraging though.

I'm also very happy that studies like this are being done. We need a whole lot more studies looking at this, long term immunity with B and T-cells, and comparing neutralizing antibody levels between vaccinated and unvaccinated who have been infected but show little or no symptoms.

On a long enough timeline, 99% turns into a much lower cumulative probability number - even if it doesn't weaken over time.

That's why it's essential to work towards having the whole world vaccinated, and to understand that weakening so we can do boosters where appropriate.

Recent statistic I heard from an ER physician in Cincinnati, Ohio: several hundred people currently in the ICU city-wide with COVID (probably delta variant), only 2-3% of them are vaccinated.

Vaccinated people can get the delta variant (though with a lower probability of infection) but are often asymptomatic or have a very mild case. The vaccine is highly effective (>95%) at preventing severe COVID even if infection occurs. Unfortunately the vaccinated can spread delta even if they have no or mild symptoms.

In Ohio vaccination rates are high in the cities and low in rural areas, which unfortunately are also the areas under-served by hospitals.

...also, being health-care workers, these 11,500 people were virtually guaranteed to be around someone sick with covid-19 more than a member of the general population.

The question will be whether Pfizer will become less effective for example 6+ months after getting it...

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