The Elephant In the Room: Herd Immunity via Tragedy

There are also terrible ways to end pandemics (and they all end)

Yesterday, I wrote an op-ed calling for the United States to release its stockpiles of AstraZeneca vaccines—the FDA will not approve them before the US trial concludes. The vaccine, however, has already shown some positive trial results (though there were some reporting issues). More importantly, it has already been widely used—eleven million doses administered in the U.K. alone—with very encouraging results. Despite some recent European scares over rare reports of clotting, it seems to have been resolved in favor of the importance of continued vaccination. 

Should the FDA have approved the stockpiles earlier? That’s for a future newsletter post. (It’s complicated but, probably not. But indeed, it’s complicated).

But the reality is what it is: the US AstraZeneca trial appears to have just met its event threshold (sufficient number of cases for meaningful comparison) so it will undergo independent review (which takes a few weeks) and then apply for an EUA. And then, judging by previous cases, it will get approved within three to four week after that. That puts the estimated date of potential approval into May—when we will already have appointments available for all eligible adults who want a vaccine. The case for releasing these doses seemed straightforward to me, and I thought the Biden administration’s concern was likely a concern about perception: sending vaccine doses abroad while people in the U.S. are still struggling to get one. So three things needed explaining about that concern, I thought. 

First, these doses will not make it here in time, so sending them abroad doesn’t hurt our ability to vaccinate people in the U.S. Second, rather than worrying about the downsides of the (incorrect) perception we’re giving away doses when people in the United States don’t have enough, we should worry about the (correct) problem that we are sitting on doses we will not be able to use here but which can do much good elsewhere—and what that means for the world’s perception of us. And third and last, with transmissible variants on the march—especially that terrible B.1.1.7 one that is more transmissible and lethal— sending vaccine doses elsewhere now is worth a lot more than sending them in a month.

One argument for holding on to all the vaccines here seems to be a version of “better safe than sorry,” that it’s preferable to have an excess rather than a shortage. This isn’t right or moral when so many countries can’t even vaccinate their health care workers, and besides, our excess is practically guaranteed at this point. It’s true that we may need to manufacture and distribute boosters that are even more effective against the variants, perhaps as early as this year, but that’s for the future, and our supply of old variant AstraZeneca won’t help us there.

I wrote that yesterday. Well, I’m thrilled that it’s just been reported that the US will indeed start releasing these stockpiles to Mexico and Canada! It’s a great start. 

Readers of this newsletter will  be unsurprised that I made a case for the foreign distribution of the vaccines that was not premised on our self-interest in the immediate sense. But, unsurprisingly, many people responded to my op-ed from yesterday saying that they supported the idea, especially to protect ourselves here.

This argument—that we should end the pandemic because otherwise it’s a threat to us here—is not rare.

Here’s a version of that from the former CDC director:

Here’s the Director-General of the WHO:

Now, as I wrote in my last newsletter, this isn’t completely wrong, because unchecked spread is of course bad in many ways.

But it isn’t completely correct either when it comes to how we eliminate the threat of dangerous new variants. As discussed in the last newsletter, within-host evolution in persistent infections in immunocompromised individuals treated with antivirals or convalescent plasma seems also to be a major that can throw up these variants.

I had linked to the studies yesterday, but here’s a New York Times article about it from this week, also explaining why within-host evolution is a concern:

A coronavirus typically gains mutations on a slow-but-steady pace of about two per month. But this variant, called B.1.1.7, had acquired 23 mutations that were not on the virus first identified in China. And 17 of those had developed all at once, sometime after it diverged from its most recent ancestor.

Experts said there’s only one good hypothesis for how this happened: At some point the virus must have infected someone with a weak immune system, allowing it to adapt and evolve for months inside the person’s body before being transmitted to others. “It appears to be the most likely explanation,” said Dr. Ravindra Gupta, a virologist at the University of Cambridge.

But let me say something else: even if population-level evolution is seen as a big (or bigger) threat, I’m not sure that this makes a clear-cut case to the person we think we are appealing to. Who’s the target audience here? Someone unmoved by the idea that it’s the right thing to do to vaccinate the world, but will do so because they fear variants? Perhaps that person exists and they are numerous. Maybe. Maybe policy-makers think that person exists in large numbers, and that’s a good reason to make that argument: policy-makers will move on this important problem because they think this is a reasonable argument that will appeal to their imagined selfish but rational, calculating individual. 

One the one hand, if it gets the world vaccinated sooner, I guess that’s a good thing.

But there is another reason I’m not sure it’s more effective when we make an argument to act out of self-interest (to vaccinate the world helps us) rather than the allegedly hippy-dippy version (it’s the right thing to do).

Unfortunately, vaccination is not the only way to stop the unchecked spread of a pathogen. The other path—one that’s terrible, tragic and which we should work hard to avoid—is natural infection, and thus widespread individual immunity and, eventually, herd immunity that will arise from letting an epidemic rage through a population.

You might remember that, early on in the pandemic, some people (in my view irresponsibly) argued for a herd immunity from mass infection path.  We saw this debate play out in the United Kingdom and Sweden, for example. There was, understandably, a lot of push back against the idea. But it seems to have resulted in a weird moment where we don’t discuss that this process can happen involuntarily as well—not as part of a deliberate strategy, but simply by failing to do whatever we need to do to vaccinate the world as fast as we can.

What about variants that develop over there that can render our vaccines ineffective, and come back to threaten us? 

I discussed this more in the post yesterday, but again, while some level of “immune escape” is not great, at the same time, I’m not sure it’s the kind of threat that will move our (imagined) completely selfish and rational individual. For one thing, the biggest problem with this virus has been that it’s novel. It’s plausible that this hypothetical self-interested individual will simply decide to keep getting boosters, and will not unreasonably, feel more than safe enough. This person may realize that re-infection/infection after vaccination isn’t the kind of threat—since the virus is no longer novel or substantively life-threatening for this person—that will move someone, purely rationally and selfishly, to work towards global vaccination of other people. 

Someone worried only with their own well-being who lives in a country like the U.S., where safe and effective vaccines are going to be available to everyone fairly soon, and where we will also likely get regular booster covering variants, can probably also figure out that the only way to ensure his own well-being isn’t to contribute to or work towards vaccinating everyone else. They can instead work on just...getting vaccinated themselves and ignoring the tragedy happening elsewhere.

The sad truth is pandemics— all pandemics—eventually end, but that’s not a win in and of itself.  If we don’t move to vaccinate the world, billions may get infected in 2021, ending the peak phase of the pandemic as an acute crisis but at a great human cost. The non-pharmaceutical interventions are hard to continue for another year. Vaccination is not something that can wait; the alternative will likely be infection of more and more people.

The goal shouldn’t be to end a pandemic as soon as possible at any cost, but to end them at an optimum intersection of minimum cost to maximum safety and well-being. Natural infection raging through the population will also get us the former—at a great human cost—but it’s the latter that is an argument for vaccination as widely and as early as possible. But tons of people seem to think only the former—appeal to selfishness—will work. Perhaps, but ironically, this may be true not because this selfish, calculating and informed person exists in any substantive proportion among us, but because that’s how the policy-makers perceive the world.