Thoughts on vaccine effectiveness

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We tend to think of a vaccine in binary terms: it is either totally effective or totally ineffective. But who knows, especially with this weird virus? Maybe a given protocol with a vaccine will only work on 80 percent of people. What would that mean?

The good news is that it would still be great for society. Suppose we have 1 million cases, and every ten days they are doubling. But tomorrow everyone gets a vaccine that is 80 percent effective, so now every tend days the number of cases only increases by 0.4. So in 10 days we have 400k cases, then 160k, then 64k, then 25.6k, then 10.2k, then 4k, then 1.6k. . .in less than six months you have it essentially eradicated.

The bad news is that people would be slow to take up the vaccine, and meanwhile some of those vaccinated will get the disease, which will not be good PR for the vaccine campaign.

Other bad news is that when you are doing testing it can be very hard to distinguish 80 percent efficacy from placebo efficacy (i.e., zero efficacy). That is, I can imagine a testing protocol in which you give somebody a placebo and the vast majority of those people don’t get the virus.

15 thoughts on “Thoughts on vaccine effectiveness”

  1. Now if only there were someone, somewhere that had suggested we do challenge trials. That way, right now, instead of just hoping that the presence of antibodies in the blood provided immunity we would know whether or not that they did. And we’d be able to tell what percentage of young healthy people that were protected by the vaccine rather than be in the situation that you describe.

    • I recently listened to a podcast about the Polio vaccine, which I knew nothing about. There was indeed an earlier “less effective” vaccine and it did in fact have one bad batch that infected some kids with polio.

      The later vaccine that became most wildly used was tested not in America but in the Soviet Union. A Russian American scientist was invited to the Soviet Union. They human trial tested it on smaller scale, then when it worked quickly scaled it up to the entire country. Lickity split, all of Russia was vaccinated. Then the vaccine went back to America. The Russians didn’t both with elaborate double blind trials, they just did it.

      I hear China is already mass inoculating its army. Let us hope our cold hearted brothers save us from this mess.

  2. Other bad news is that when you are doing testing it can be very hard to distinguish 80 percent efficacy from placebo efficacy (i.e., zero efficacy).

    Extending this a bit, as a society we still prioritize anecdotes over studies when determining what we believe. This will create enough doubt over the real efficacy of the vaccination that it will be adopted by far fewer people, even further limiting its impact on society.

    On the plus side, it would create another axis over which we can hate each other. The anti-vaxxers can combine with the COVID disbelievers to hate people who use vaccinations and who think COVID is a serious issue and vice versa. And while we probably don’t *need* another reason to divide and hate each other, we (as a society) are always on the lookout for another battle front. This would do nicely.

  3. Why would anyone trust the judgements of politicians or public health frauds on vaccinations?

    They’ve clearly been shown to be unreliable, unscientific and incompetent on many levels.

        • Seriously?

          Go back and read your own post. It was seething with disrespect.

          I was just being snarky. Your disrespect led you to make an unusually dangerous argument.

          • For the record, the guidelines I offer are to be respectful to me and to other commenters. But it is ok to be hard on classes of people or on famous individuals.

  4. I’m going to take issue with you calling this a “weird virus”. Is there really anything weird about this one? I suspect all viruses are equally weird, and the only reason this one seems weird to us now is that we’ve done such massive testing that it has allowed us to see all the corner cases that we usually miss with say flu.

    I mean, is there any symptom, reproduction/spreading behavior, asymptomatic behavior, etc. that we could say with any degree of certainly does *not* occur with flu or cold-like viruses?

    • My hunch is that you are right, that many cold viruses are equally “weird” and do all kinds of different weird things to different people, and that we don’t (maybe can’t) pay attention because the typical symptoms are mild and so all the weirdness flies below the radar. I think it’s a very common human experience to frequently and inexplicably feel a little weird or off or out of it or fatigued or dizzy or upset stomach, etc. and we rarely think those may be the consequence of an otherwise asymptomatic viral infection. I suspect that many deviations from typical human functioning are due to infections that are hard to detect and which we aren’t inclined to focus upon.

      • I would speculate actually that many of the symptoms being reported from asymptomatic or mind infections from this virus won’t pan out to be real or at least will be very uncommon. Many of the reports of this or that new symptom are anecdotal borderline anecdotal. Even physicians and many scientists seem eager to attribute anything that happens within a few months of getting the virus to the virus, but absent the current pandemic, they wouldn’t be monitoring patients so closely and wouldn’t notice the subtle health issues people likely would’ve had anyway or perhaps already had beforehand.

        • I strongly suspect we are making big errors on both sides of the pattern-noticing ledger. We are ignoring or failing to recognize important things actually caused by cv19, and that we are falsely attributing coincidental symptoms or complaints to the new virus. Those are abstractions of “Type I and Type II” errors, but in this case quite significant.

          Our map does not even come close to reflecting the territory of the reality of all the different things that can and do go on in the course of viral infections, in terms of capturing the the enormous complexity of the chain linking biochemical processes to macroscopic physiological consequences, but even though we know that, it is very difficult to avoid the “passive confirmation bias” of having our whole process of investigation, thinking, and observing warped by the oversimplified model we hold in our minds, which acts like a set of blinders.

          This is a well-known danger against which detectives in criminal investigations are repeatedly warned. The mind tends to create a “model” of the incident, the narrative story of what transpired, and the investigator won’t even be aware of their tendency to focus on the primary suspect, exaggerate the incriminating nature of evidence pointing in that suspects direction, while overlooking evidence that points in other directions.

          If this pandemic should teach us anything it is that this is a time for radically throttling up our epistemic humility and levels of intellectual care, discipline, and rigor, and to be willing to question and “stress test” existing theories for analytical fragility, and think through possibilities with larger “inferential tolerances”, that is, “we are assuming a, b, and c, but how would our conclusions change if any of those failed to replicate, or were even off by 10%, 50%, 100%, etc.”

          As a general civilizational-level scientific program, we should be trying to reassess the analytical fragility of all our models of complex phenomenon, and trying either to devise profitable ways to make them more robust, or else to admit our fundamental inability to make confident and precise forecasts in those domains.

  6. They are talking about a two shot regime. One shot does half the job, then a few days afterward when the immunity system partially adapts, hit it with second possibly different shot. Sounds like the flu protocol which youngsters generally skip. But it will make a big difference.

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