By Columbia Mailman School of Public Health
In the weeks since the emergence of the Omicron variant, the United States had once again led the world with a record of confirmed cases of COVID-19. In a conversation with Transmission, Columbia Mailman Professor Jeffrey Shaman, a world-renowned authority in infectious disease modeling, says the actual number of infections is many times larger still and they continue to accumulate at a near-exponential pace. On the plus side, his computer models suggest case numbers may subside as quickly as they climbed, peaking by mid-January.
WE’RE TWO YEARS INTO THE PANDEMIC. WHAT’S CAN WE EXPECT NEXT?
When it comes to Omicron, we can look at other countries but isn’t a perfect comparison. In South Africa, Omicron has already come down. But it’s summer there and the virus has less opportunity to spread.
U.S. COVID cases are projected to peak in mid-JanuaryWe could look at England, but we know from past experience that what happens there doesn’t always match what happens here. If you look at our projections, Omicron may peak as soon as this week in New York City. Other areas of the country could peak a couple of weeks later. Our median projection has 5 million confirmed cases during the worst week with an upper bound of more than 8 million, although the actual number of infections would be much higher.
DO YOU EXPECT THE CASE NUMBERS WILL COME DOWN QUICKLY?
Right now, we’re seeing an average of more than 500,000 cases every day in the U.S. And the numbers are increasing. A virus that aggressive can rocket up until it burns through its fuel of susceptible cases and comes crashing down. On a national level, this decline would be slightly less dramatic than we might see here in New York.
BUT AREN’T THERE STILL A LOT OF PEOPLE WHO HAVEN’T BEEN INFECTED?
When people have mild symptoms, they might not realize they are infected or they might not bother getting tested. We estimate that only about 18 percent of infections are reported as cases. At the peak, there may be more than 6 million infections per day. If people test using an at-home kit, the results typically aren’t captured by health authorities. That’s not to say everyone will get infected. Not everyone is susceptible. Some people have been infected or boosted recently enough to be protected. It’s not like two years ago when everyone is a sitting duck. But compared to Delta, Omicron has a much bigger pool of people to infect.
THE NUMBER OF PEOPLE SICK RIGHT NOW IS STAGGERING.
It’s unprecedented. It’s often a mild sickness, but not always. People are still going to the hospital; people are still dying. The sheer number of cases is the problem. If each case is half as likely to end up in the hospital but there are twice as many cases, we’re still looking at hospital demand just as bad as last winter. We won’t see the peak in hospitalizations until after the peak in cases. Already, we’re seeing a lot of disruption and lost productivity. Flights are canceled. Subway lines are shut down. Many police officers and firefighters are out sick. We’ll likely see a lot more teachers out sick.
WHAT MIGHT THE NEXT YEAR LOOK LIKE BEYOND THE OMICRON WAVE?
When the next wave hits and how severe it will be are unknown. After four or five months, we could see descendants of Delta or Omicron re-establish themselves when people’s immunity wanes, or we could see an entirely new variant emerge. We might need another booster this year, possibly even two. There’s also a chance we won’t see a significant new variant for much longer. There may be a limit to how much the virus can change and radically evade immunity.
ARE WE MORE LIKELY TO SEE VARIANTS LIKE OMICRON THAT SPREAD QUICKLY AND ARE RELATIVELY MILD?
New variants don’t need to spread more quickly, they simply need to overcome pre-existing immunity. There is also no reason to expect the next outbreak will be mild. Delta wasn’t milder than the variants it superseded. Given how aggressively SARS-CovV-2 spreads before causing severe symptoms, I see little evolutionary advantage conferred by a milder variant.
THE PERENNIAL PANDEMIC QUESTION: WHAT CAN WE DO TO PROTECT OURSELVES?
It bears repeating: If you haven’t been vaccinated, get vaccinated. If you haven’t boosted, boost. Vaccination will protect you against the severe consequences of this virus. On top of that, having a booster may protect you against infection. Breakthrough infections happen but the shots still do a lot to protect us. Mask up. Stay distant and avoid mass gatherings for now. If you’re feeling any symptoms or think you might have been exposed or are planning a visit with a friend or family member, get tested.
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