Who is right about the Delta variant?
Both the "downplayers" and the "alarmists" need to think ahead.
The Covid-19 alarmists and downplayers are at odds once again. Unsurprisingly, the factions disagree on what Delta means for the pandemic overall. But they share a talking point which both sides may come to regret: that most hospitalizations are occurring among the unvaccinated. While that’s currently true, it won’t be soon in many areas.
Why? Because as more people get vaccinated, the percentage of hospitalizations due to "breakthrough" infections in vaccinated people also rises. The visualizations we made for Inside Medicine below clarify this phenomenon. (Note: these are models based on the data we have; they represent qualitatively what is happening, though the numbers used are best estimates.) Yes, increasing rates of vaccination renders the overall size of the pie smaller (i.e. the total number of hospitalizations drops) but the relative size of the slice representing breakthrough cases grows. This was bound to happen for any variant, but Delta has magnified and accelerated the effect. Also, in the Delta era, the breakthrough hospitalization pie chart appears destined to be a somewhat larger circle than it would have been for other variants, with the contribution from breakthrough infections becoming greater and noticeable sooner. If we don’t acknowledge this, and explain it over and over, people will feel betrayed because we told them that “breakthrough infections and hospitalizations are rare.”
Ironically, these models indicate that vaccination has only become more crucial in the Delta era. The vaccines still massively reduce bad outcomes, though a bit less so. The vaccines still substantially decrease infection rates, though again, less so. The combined result? The Delta era indeed feels different on the ground—not just in your news feeds.
Ironically, these models indicate that vaccination has only become more crucial in the Delta era.
Yes, these visualizations show that at some point, in highly vaccinated areas, breakthrough cases will make up a substantial fraction (and eventually a majority) of hospitalizations. But they also show that the overall number of hospitalizations will continue to be far lower than without vaccines.
Look at the Delta and pre-Delta animations again. Notice that we incorporated some key information from recent studies (and the Centers for Disease Control and Preventions leaked slides which summarize several of them). First, Delta appears to be more contagious (a higher “attack rate”) than pre-Delta variants. Second, Delta breakthrough infections appear more likely than other variants. Moreover, just to be conservative, we incorporated a higher Delta hospitalization rate for the vaccinated only, but not for the unvaccinated. Using that assumption paints the vaccines in the worst possible light. Even still, it’s clear that vaccines remain tremendously powerful.
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What do the downplayers and the alarmists each have right and what do each have wrong? First, let’s rebrand, calling the downplayers rationalists, and the alarmists concernists.
The rationalists emphasize that even with Delta, overall hospitalizations and deaths are drastically lower than in the pre-vaccine era. To them, something like “normal” life should go on because we can’t prevent every bad outcome. The crux of the rationalist perspective is that in the pre-vaccine era, around 10% of coronavirus infections required hospitalization and (once asymptomatic infections were included) under 1% of the cases were fatal. This meant that if 265 million Americans eventually were infected (assuming herd immunity could be reached with 80% of the nation’s 330 million people infected), 26.5 million would be hospitalized, and around 2 million people would die. Most rationalists understood getting the number of deaths well under 2 million was worth avoiding by flattening the curve and limiting some (or a great) degree of public life until vaccines became available. If the vaccines divided the number of scary outcomes by 20, a relatively small number of additional deaths would be added from there on, say an additional 15% of what we’d lost already. If Delta doubles bad outcomes among the vaccinated, the numbers would still sum to a small fraction of what we faced in a no-vaccine alternate reality. In short, rationalists think Delta, isn’t worth panicking over. (The typical rationalist more-or-less thinks that the unvaccinated have made their own choices, and we shouldn’t have to worry about them.)
The concernists see any rise in cases—but especially rises in hospitalizations or new deaths—as an avoidable tragedy, worth taking almost any means to stop. They feel that those with breakthrough infections are “being punished” by those spurning vaccination. Because some degree of breakthrough infection is inevitable, especially among those with compromised immune systems and children not yet eligible for vaccines, high quantities of circulating virus increase breakthrough infections, ultimately leading to hospitalizations or worse. Concernists want mask mandates to stop the unvaccinated from causing breakthrough infections, but they also worry about unvaccinated people too. Yes, the unvaccinated can make their own choices, some argue (others believe in mandates), but many have been misled by cynical political leaders who continue to shrug off the severity of Covid-19. The unvaccinated deserve to live even if they “have been misinformed” about this disease, the thinking goes. On top of that, spikes in unvaccinated regions risk higher rates of breakthrough or repeat infection in hospital wards, where some of the most at-risk vaccine recipients can be found.
Who’s right and who’s wrong? So far, both the rationalists and the concernists are correct that breakthrough infections are rare, and breakthrough hospitalizations rarer still; to see that, just look at the pie charts above when 50% of the population has been vaccinated, which is where the US is now. But, as mentioned, both groups are wrong if they believe that this will continue to be true as vaccination rates rise. Breakthrough cases and hospitalizations will only become more common over time, especially if immunity provided by the vaccines wane over time, or yet another variant worsens things.
Many rationalists are correct that the protection currently offered to the vaccinated is so good that breakthrough cases themselves could never overwhelm the healthcare system. But they’re wrong that the numbers in many parts of the country won’t add up and that it is not worth trying to do something to impede that. What we are seeing now is not just some small rounding error. These are real lives, worth saving. Slowing down Delta means more time to vaccinate more people and more time to find effective therapeutics, a few of which do make a small but real dent. The number of American lives on the line may no longer be 7 figures, but preventable deaths that reach 5- and 6-figures shouldn’t be shrugged off just because we’re tired.
The number of American lives on the line may no longer be 7 figures, but preventable deaths that reach 5- and 6-figures shouldn’t be shrugged off just because we’re tired.
Many concernists have much of that inverted. They’re wrong that breakthrough cases could overwhelm the healthcare system. A highly vaccinated population may have tons of breakthrough cases (and maybe even more cases than ever in some regions), but for the most part, vaccinated breakthrough cases are not the plague that unvaccinated ones were and are. Strangely, some concernists are both extremely pro-vaccine and not giving the vaccine its full due in the Delta moment. The vaccines continue to keep most people out of the hospital. That said, a small number of hospitalizations and deaths are inevitable. Asking people to stop all life indefinitely and mask forever (which does seem to grate on people), comes at a price. We may save a few lives today with a “do everything now” strategy, but that could cost us later if everyone gets burned out and we later again ask people to hunker down and mask up in the face of an even worse variant, or a new disease altogether. That said, doing the “easy stuff” to slow down Delta while we sort out whether immune-compromised and older people need boosters could save many lives.
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Renewed interest in vaccinations among the undecided is good news. But time is short. Delta moves quickly and is less forgiving for the unvaccinated. The vaccines still work, though a bit less well against Delta. The time to shore up vaccination efforts is now. Delta appears to be formidable enough a foe that we can’t simply ignore it.
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What do you think we should do about Delta? Who has it right? Please leave your comments below.
‡Special thanks to Dr. Kristen Panthagani for the data visualizations created for this Inside Medicine article.
References and further reading:
The CDC's leaked slides on vaccine efficacy and Delta: https://context-cdn.washingtonpost.com/notes/prod/default/documents/54f57708-a529-4a33-9a44-b66d719070d9/note/7335c3ab-06ee-4121-aaff-a11904e68462.#page=1
A recent preprint on age-specific infection fatality rates of SARS-CoV-2: https://www.medrxiv.org/content/10.1101/2021.07.29.21261282v1
Dr. Panthagani's explainer on the concept behind the data visualizations here: https://youcanknowthings.com/2021/07/21/some-vaccinated-people-are-getting-covid-what-does-this-mean/