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Comment by standardUser | Hacker News Reader

This does mesh with the data out of Israel showing a reduced efficacy in the Pfizer vaccine against Delta. That data was considered an outlier (there were also some specific criticisms that I have since forgotten), but now perhaps that study will be taken more seriously. Israel's solution was to approve a third shot for high risk individuals. Approvals for third shots should be happening in the US very soon too.

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I saw an interesting point (I think it was a scientist quoted in the NYT) that said once a vaccine out in the general public, it gets incredibly hard to get good efficacy numbers, because there are so many things that correlate with vaccine status—age, wealth, risk level, attitude towards COVID, geographical area—that also can affect risk of being infected/hospitalized.

The specific criticism, that even the original author accepted later, was, that the growth of the infections in Israel during the study where focused in cities with lower vaccination rates compared to the whole of Israel. I.e. the effectiveness of the vaccine was underestimated in the study. Additionally, you have to consider that Israel got the vaccine very early, i.e. more people had their shots a longer time ago.

Meanwhile, Biontech (the developer of the Pfizer vaccine) applied in Europe for approval to administer third shots 6 to 8 month after the second shot. It remains to be seen, whether the higher concentrated Moderna shots will need a third one a bit later.

One has to be very careful to properly separate a lot of different aspects for drawing general conclusions, regarding this pandemic.

If Pfizer wore off in 6-8 months what does it say about the next year? A big chunk of the population would have lost a sizable chunk of immunity no? Are we really confident that global vaccination would be high at that point? I really wish US ordered, manufactured and donated a ton more to quash this thing

My understanding is that this is more about generating a robust immune response in the first place than about losing protection over time. There have been a lot of studies looking at third shots, at natural immunity combined with vaccines, and even at mixing vaccines. And the general idea is that there are ways to generate a more optimal immune response, and the vaccine courses given emergency authorization are probably not the best of all options.

Researchers have yet to determine how long natural immunity lasts, and it may last for a very long time. Immunity from vaccines is expected to be at least as durable as natural immunity, though some studies have shown a slight decline in protection over months. But there are definitely no clear signs yet that an annual shot will be necessary.

Ah got it. I didn’t catch the nuance that the efficacy drop is specific to delta. I wrongly assumed that it was for all variants. Thanks!

It did not so much wear off as that it simply doesn't protect as well against this new strain. It most likely still protects just fine against the alpha variant but that one has now been all but displaced.

Crazy that we can see the pure savagery of evolution right in front of us

The rate at which viruses reproduce is what allows you to see this, every biology freshman probably does the e-coli + arsenic experiment, it's a real eye opener as to how slow walking a treatment can actually create a resistant strain.

Is it wearing off or just reduced efficacy to begin with? My understanding is that dosing between the vaccines were all different

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