We know enough about Omicron to know we’re in trouble

Updated at 12:00 p.m. ET on December 17, 2021

Much has changed for Omicron in just two weeks. By early December, the variant was barely present in Europe, appearing in 1 to 2% of COVID cases. Now it’s accountant 72 percent of new cases in London, where Everybody seems to know someone with COVID. In the UK and Denmark, the number of Omicron cases is doubling every other day. The same exponential growth is happening – or will happen – also in the United States, just in time for the holidays.

What seemed likely at the start of the month is now quite certain: a big Omicron wave is coming, in addition to an already substantial Delta wave. There are still unknowns about the variant, such as the exact severity of these cases. But we know enough about Omicron to understand that it’s time to act. “If we wait until our hospitals look like they’re starting to fill up,” says Lauren Ancel Meyers, director of the UT COVID-19 Modeling Consortium, “then it will be too late. “

The most intriguing unknown – the one we’d like to place our hopes in – is whether Omicron could be softer than Delta. But a milder, more transmissible virus can easily make so many people sick that it ends up increasing hospitalizations and deaths overall. Here are some simple calculations to explain the danger: Suppose we have two viruses, one twice as transmissible as the other. (For the record, Omicron is currently three to five times more transmissible than Delta in the UK, although that number is likely to decline over time.) And suppose it takes five days between a person’s infection and infection of others. After 30 days, the most transmissible virus now causes 26, Where 64, times more new cases than the least transmissible. Exponentials are one hell of a growth hack. If we’re betting on the idea that Omicron is milder for wintering, then we better hope that it really is, really Benign.

The vaccines will be reduce the proportion of hospitalizations a lot in these extra cases, especially because Omicron infects a lot of people who have been vaccinated. But it’s a long descent on this exponential curve. Moreover, when so many cases accumulate at the same time, their effects begin to spread throughout the lives of those who are not sick. If Omicron passes through a workplace, it may present a temporary inconvenience. But if that workplace is a school, then the school will have to close, disrupting the lives of every child and parent. If that workplace is a hospital, then doctors and nurses cannot work. This has been a problem in South Africa, where Omicron is already dominant and nearly 20 percent of the healthcare workforce has COVID. Even though most of these cases are mild, a large number of people falling ill at the same time will change the daily reality.

However, not all cases will be mild, and even a small rate of hospitalization in addition to a huge number of cases will be a large number. With Delta, “we were already heading for a bad winter,” says Roby Bhattacharyya, infectious disease specialist at Massachusetts General Hospital. Now, as my colleague Ed Yong reports, Omicron could push a collapsing healthcare system even further into disaster. Hospitals are already struggling with the flu and other winter viruses. They are already canceling elective courses surgeries. After another year of pandemic exhaustion, they just might not have the staff to create the surge capacity that barely got us through last winter. Overcrowded hospitals mean care gets worse for everyone with COVID, but also for everyone with a broken hip or stroke or an urgently needed baby. Omicron’s transmissibility is a danger because high levels of COVID cases are accompanied by second-order consequences that transcend the risk to individuals.

If there is no change in behavior or policy, this year’s winter wave would peak at about double last winter’s hospitalizations at its worst, and 20 percent more deaths, according to the projections. more pessimistic from Meyers and his team at the University of Texas at Austin. The team developed a total of 18 scenarios, based on different assumptions regarding the inherent transmissibility and immune escape of the variant, booster uptake, and vaccine efficacy against hospitalization and death. The most optimistic projection projects a similar number of cases to last winter, but hospitalizations and deaths at about half of what they were then, assuming the vaccines maintain their very high protection. against serious illnesses.

Vaccine protection against serious illness should last longer than it is against infection, but it can still take a hit. Very preliminary data from South Africa’s largest health insurer suggests that two doses of the Pfizer-BioNTech vaccine was 70 percent effective in preventing hospitalizations from Omicron infections, up from 93 percent previously. If true, it is a “huge decrease,” Meyers says, and one that fits his team’s darker projections assumptions, but not the darkest. When they modeled scenarios in which the effectiveness of the vaccine against hospitalization decreased by that much, they found a difference of tens of thousands of deaths.

The available evidence on Omicron’s inherent seriousness is likely to be biased in such a way as to make it more promising. First of all, hospitalizations lag behind infections. “Omicron has been around for three weeks,” Bhattacharyya says. “But so many of these infections have happened in the last week of these three because of exponential growth.” Second, the first people infected can fake young people and are therefore more likely to have mild cases, regardless of the variant. And third, some of the softness attributed to the virus may instead be the result of existing immunity. In South Africa, where doctors are reporting relatively low hospitalizations compared to previous waves, many cases are likely re-infections, given that the majority of people there have already had COVID. Data from the South African health insurer suggests that Omicron may have a 29% lower risk of hospitalization than the original virus, when adjusted for risk factors such as age, gender, vaccination status, and a documented previous infection, but many previous infections may be undocumented, making the risk reduction greater than it actually is. (A recent analysis of the first UK cases revealed “at most, limited changes in severity from Delta.”) Meanwhile, Omicron “is going to spread so quickly that waiting for definitive answers will be to wait. too long, “Bhattacharyya said. “If this is anything but the best of times, and we wait until we find out, it will be too late to mitigate the worst. “

Another unknown is where Omicron’s tendency to spread faster than Delta comes from. Is it inherently more transmissible, better at evading immunity, or both? And how many of one or the other? “We don’t understand the new equilibrium,” says Lone Simonsen, epidemiologist at Roskilde University, Denmark. In the long run, if Omicron’s benefit is largely based on immune evasion, then Delta and Omicron could co-circulate like multiple influenza lineages, says Katia Koelle, an evolutionary virologist at Emory University. Getting sick with one variant may not protect you much from the other. But if Omicron has advantages in both immune evasion and transmission, then Delta could eventually disappear.

Either way, in the short term we will have a massive Omicron case count in addition to a massive Delta case count. Together, they will infect large numbers of people, vaccinated or not, and put a strain on an already overburdened health system. Boosters, social distancing, rapid tests, and masks can slow this impact. We’ll know more about Omicron soon, but we already know enough.


This article originally distorted the University of Texas’ most pessimistic projection for COVID-19 deaths this winter. According to updated information from the university’s modeling team, the projection shows only 20% more deaths than last winter’s worst, not twice as many.



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