The new variant seems to be our quickest one yet. That makes it harder to catch with the tests we have.

 
It certainly might not seem like it given the pandemic mayhem we’ve had, but the original form of SARS-CoV-2 was a bit of a slowpoke. After infiltrating our bodies, the virus would typically brew for about five or six days before symptoms kicked in. In the many months since that now-defunct version of the virus emerged, new variants have arrived to speed the timeline up. Estimates for this exposure-to-symptom gap, called the incubation period, clocked in at about five days for Alpha and four days for Delta. Now word has it that the newest kid on the pandemic block, Omicron, may have ratcheted it down to as little as three.
 
If that number holds, it’s probably bad news. These trimmed-down cook times are thought to play a major part in helping coronavirus variants spread: In all likelihood, the shorter the incubation period, the faster someone becomes contagious—and the quicker an outbreak spreads. A truncated incubation “makes a virus much, much, much harder to control,” Jennifer Nuzzo, an epidemiologist at the Johns Hopkins Center for Health Security, told me.
 
Already, that’s what this variant seems to be. In less than a month, Omicron has blazed into dozens of countries, sending case rates to record-breaking heights. If, as some scientists suspect, this variant is so primed to xerox itself more quickly inside us—including, it seems, in many people with at least some immunity—that leaves punishingly little time in which to detect the virus, intervene with antivirals, and hamper its spread.
 
A pause here. We are still just weeks into our fight against Omicron, and it’s not easy to gather data on incubation periods, which might differ among populations, or suss out exactly how the virus is tangoing with our cells. But the early warning signs are here—and as my colleague Sarah Zhang has reported, we know enough to act.
 
All of this, then, ups the urgency on having tests that can quickly and reliably pinpoint Omicron. “If Omicron has a shorter incubation period, that’s going to wreak havoc on how we test for it and deal with it,” Omai Garner, a clinical microbiologist in the UCLA Health system, told me. But testing in the United States remains slow, expensive, and, for many, infuriatingly out of reach. We’re ill-prepared for the incoming Omicron surge not just because it’s a new version of the coronavirus, but because it’s poised to exploit one of the greatest vulnerabilities in our infection-prevention toolkit. The coronavirus is getting faster, which means it’s also getting harder to catch.
 
Since the World Health Organization designated Omicron as a variant of concern at the end of November, the virus seems to have popped up just about everywhere. Researchers are tracing cases of it back to schools, child-care centershotelsuniversitiesweddings, and bars. And they’re finding it at office holiday parties, like the one at a restaurant in Oslo, Norway, where about 80 people may have caught or transmitted Omicron.

In a research paper describing the Oslo outbreak, scientists noted that, after the event, symptoms seemed to come on quickly—typically in about three days. More troubling, nearly every person who reported catching Omicron said that they were vaccinated, and had received a negative antigen-test result sometime in the two days prior to the party. It was a clue that perhaps the microbe had multiplied inside of people so briskly that rapid-test results had rapidly been rendered obsolete.

The time lines described by the Norwegian researchers are preliminary, and might not be representative of the rest of us. But they appear to match up with early, sometimes-anecdotal reports, including some out of South Africa, one of the first countries to detect and report Omicron’s existence. Shorter incubation periods generally lead to more infections happening in less time, because people are becoming more contagious sooner, making onward transmission harder to prevent. Ajay Sethi, an epidemiologist at the University of Wisconsin at Madison, told me he still wants more data on Omicron before he touts a trim incubation. But “it does make sense,” he said, considering the variant’s explosive growth in pretty much every country it’s collided with. In many places, Omicron cases are doubling every two to three days.

Nailing the incubation interval really is tough. Researchers have to track down sizable outbreaks, such as the Oslo Christmas party; try to figure out who infected whom; wait for people to report when they start feeling sick—always a fickle thing, because symptoms are subjective—then, ideally, track whether the newly infected are spreading the virus too. The numbers will vary depending on who was involved: SARS-CoV-2-incubation periods could differ by vaccination status, underlying health conditions, infection history, age, and even the dose of the virus people get blasted with. To complicate things further, the start of symptoms tends to lag behind the start of contagiousness by, on average, a couple of days; when symptoms begin earlier, transmission might not follow to exactly the same degree.
 
Read the full article here: 
https://amp.theatlantic.com/amp/article/621066/

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