[EvgeniyZh]

I'd expect that case fatality rate would significantly reduce after 60+ population (which is 90%+ of deaths) is vaccinated. However, even though more than 80% of 60+ got second dose already, case fatality rate is approximately the same. I don't have any good explanation for that.

[corty]

Death usually comes 2 to 4 weeks after hospitalization which comes 1 to 2 weeks after infection. So the drop in death rates should be visible 2 to 4 weeks after the drop in hospitalizations, and should be less steep initially.

[EvgeniyZh]

There was large amount of 60+ vaccinated with second dose 2 to 4 weeks ago. Iirc it was at least 50%.

If half of population responsible for 90% of deaths is vaccinated it should affect death-per-case ratio.

[corty]

Vaccinated with a second dose means full immunity 1 week after, possible death 3 to 7 weeks after (1 + (1 to 2) + (2 to 4)). So a decline should start to be visible since last week maybe. But I wouldn't get nervous for another 2 to 3 weeks in case it doesn't fall sharply, data is always noisy and everything is spread out the more dependencies on previous events and times there are.

[EvgeniyZh]

We don't need full immunity to see the effect tho.

[corty]

Right. But still, don't worry yet, worry when it hasn't shown improvement in a few weeks.

Edit: Also, when you look at the JHU data (e.g. via google), it shows a peak at Jan 15th in the number of cases followed by a steady decline. The number of deaths peaks on Jan 28th, followed by a similar, steady decline. Which is as expected, so I would say we are already seeing the effects on the number of deaths.

Sorry that I didn't look at the data earlier before replying.

[EvgeniyZh]

I'm looking on case fatality rate: cases and death count are too volatile and depend on many factors.

My hypothesis (it's not mine but I agree with it): if population with high death risks is disproportionately vaccinated, at the level it can make visible effect on case count for this population, it should have effect on case fatality rate. Of course, multiple factors can reduce/slow down the decline, but it should be there. Reducing death probability by half for the 60+ people without changing anything else should significantly reduce case fatality rate.

Yet the data does not support it: https://ourworldindata.org/coronavirus-data-explorer?zoomToS...

The case fatality rate peaked at the end of November, slightly declined until mid-January, then grown a bit and is almost constant in last three weeks.

So, the options I see are: either no effect at all can be seen yet behind the noise (it's hard to believe for me), or there is some factor compensating for the case fatality rate reduction (I can think of what could increase fatality that much and exactly compensate the effect), or the hypothesis is wrong (I can't see why either)

[Plasmoid2000ad]

Good points, and Vaccination itself has a lag effect as well, If i understand it correctly. I've heard that someone vaccinated with 2nd dose today will not have the protection percentage for 10days+ or so - Which needs to taken into account with these figures.

The vaccination also does no good if you are already infected, and with the spike in infections in Israel coinciding with vaccination ramp up, those will be tricky to separate out.

[runako]

> case fatality rate is approximately the same

If you vaccinate more people, you would expect that the cases that present at a physician will be selected to be the most severe. If the vaccine reduces most infections to very mild or asymptomatic cases, they will not be counted in the statistics at all.

So it would make sense that introducing a broadly effective vaccine would increase the case fatality rate. (You would also expect fewer severe cases, which is the whole point.)

A functioning vaccine should affect the CFR by changing the denominator of measured cases.

I am reminded of an analogy from improvements in battlefield medicine. As battlefield protocols (on-site treatment, rapid evacuation, etc.) have become more effective, battle fatality rates have fallen. But they have been replaced by a rise in severe chronic injuries like amputations.

[EvgeniyZh]

> If you vaccinate more people, you would expect that the cases that present at a physician will be selected to be the most severe.

Most of cases both before and after vaccinations are not severe. Moreover, the share of severe cases seems to stay the same or even increase ( https://datadashboard.health.gov.il/COVID-19/general , I hope it can be google-translated or something).

As I explained in other reply ( https://news.ycombinator.com/item?id=26142482 ), I expected change in fatality rate due to disproportional vaccination of the group with most of the fatal cases. For 60+ fatality rate is very high, and many of them are vaccinated. For everyone else, the opposite. I agree that if only severe cases were registered, we should've been looking at case number instead (which would be more stable since almost all of those would be registered).

[runako]

> the share of severe cases seems to stay the same or even increase

I can't read the dashboard, but as I indicated this is what you would expect if you have a vaccine that broadly works at controlling the most severe forms of the disease. Vaccinated people whose infections manifest as nothing or a day or two of lethargy are not going to get counted in the statistics.

> I expected change in fatality rate

your expected change in the fatality rate needs to take into account that the real-world denominator has changed and that will not be apparent if you just divide number of fatalities by number of cases. (Because vaccinated people may be more likely to be asymptomatic, and we expect them to not get sick enough to ever present as a case.)

It's important to look at the number of people hospitalized or dying.

[EvgeniyZh]

One again, out of population who are responsible for 90% of deaths (and 10% of cases), more than 80% are vaccinated. Everyone else, like 25%. This got to result in disproportionate change in number of cases and number of deaths.

[whiddershins]

Most vaccinated people will not test positive.

This reduces the number of cases.

[dennis_jeeves]

>I don't have any good explanation for that.

A good explanation is that the vaccine is not working. ( people are in denial) I looked at the Pfizer numbers and my conclusion is the it's doing nothing.

[pault]

It will take 6-8 weeks after large scale vaccination to start seeing the results. Deaths usually occur six weeks after infection, and it takes a week to reach full immunity after vaccination.