Reasons for Omicron optimism
Right now we're somewhere between pandemic and endemic, and it feels pretty weird
As 2021 went on it become increasingly clear that the Covid-19 pandemic wasn’t going to have a firm end date. The vaccines proved highly effective at preventing severe disease and death, turning the coronavirus into something akin to a mild cold or flu for most of those protected against it. But ever-evolving virus, particularly its latest incarnation as the Omicron variant, still figured out ways to spread from person to person, even among the vaccinated.
Epidemiologists now speak of the virus becoming endemic, widespread but less harmful, eventually fading into the background of all the other respiratory afflictions we deal with each year — colds, flus, RSV, pneumonia. That at least was the fate of the Spanish flu in the early 20th century, whose viral descendants still circulate among us today.
We’re not at that point with Covid yet. Vaccination rates are still too low, and there are still millions of unprotected people out there who haven’t been infected or exposed. But there are signs that Omicron — which at this point looks to be much more transmissible than previous variants as well as somewhat less likely to cause severe disease — is getting there.
One piece of evidence: the changing relationship between infection and hospitalization rates. For most of the pandemic, that relationship was pretty rigid. The chart below, for instance, plots the relationship during the ramp-up of the Delta wave — the period from July 1 of last year when new cases were at a lull, all the way to the beginning of October, when new Delta cases peaked.
(Datavis nerds: you can think of this as a timeline running from July to October, plotting each day’s new case and current hospitalization counts, although strictly speaking it’s a connected scatterplot.)
The relationship is remarkably linear: when average daily new cases hit 50,000 there were 30,000 people in the hospital. At 100,000 cases there were 60,000 hospitalizations. And so on, in a straight-line shot all the way through October.
You can do the same exercise for other waves. Here, for instance, I’ve added the ramp-up of the big winter wave from 2020-2021, running from roughly October to January.
The line’s a little wigglier because of drops in reported cases during the holidays, first for Thanksgiving and then for Christmas/New Year. But the overall slope of it is very close to the Delta wave’s, indicating a similar relationship between cases and hospitalizations as far back as 2020.
Now, I’ll add one more layer. It’s for the first month or so of the Omicron wave, running from December 1 through yesterday. See if you can spot the difference.
The slope of the Omicron line is much less steep — so far, the new variant is yielding considerably fewer hospitalizations per case than the other two waves I’ve charted. During Delta, for instance, the daily hospitalized population was running at roughly 60 percent of daily new case counts. For Omicron, so far, that figure is roughly 12 percent.
A big part of this, of course, is that there are simply so many new Omicron cases, dwarfing numbers from previous waves of the pandemic. Hospitalizations are likely to continue to increase. But at this point it seems unlikely (knock on wood) they’ll follow the same growth trajectory as the previous waves: if we were proceeding at the same pace we saw during Delta, we’d be up to about 330,000 hospitalizations right now. The link between case and hospitalization is weakening.
Will this pattern hold? There’s good reason to think, or at least hope so. Evidence is mounting that Omicron is inherently less severe than previous outbreaks. Population-wise we are also better protected now: more than 70 percent of the population had received at least one dose of vaccine by December 1, compared to about 55 percent at the start of Delta. More people also have some form of natural protection via a prior infection.
Even if Omicron is less likely to result in hospitalization, however, it can still cause serious problems for our health care system. A smaller percentage of a much bigger number can still yield a pretty big result, and we’re seeing that happen in some hospitals already.
All told it feels like we’re in this weird, transitional space: on the one hand there are very real signs that the pandemic is heading toward endemicity, with lower risk than ever for individuals who are vaccinated. But on the other this latest surge in cases presents a true population-level threat in terms of health care capacity.
My hope is that with the passing of Omicron — and it appears to be much faster-moving than previous variants — we will finally have hit a major turning point in our relationship with the pandemic. The overwhelming majority of people will be vaccinated, and most of the remaining unvaxxed will have already been exposed to the virus and infected with it. If subsequent evolutions of the virus continue to lessen in severity, we could be well on our way — finally — toward treating it like any other cold or flu.