Fresh off the Christmas holiday, the Centres for Disease Control and Prevention has updated its guidance on how long people should isolate away from others if they’ve been infected by or exposed to the coronavirus. The change effectively cuts the waiting period in half for many people, particularly those without symptoms. But at least some experts aren’t too pleased, arguing that the new recommendations are too lenient, since they largely won’t depend on testing, and that people’s health is being placed in danger to placate business interests.
The CDC announced the changes on Monday afternoon. Previously, people who tested positive for covid-19 have been told to isolate at home for 10 days, starting from their positive test result. Now, the CDC says that people should isolate for five days, then, if they have no symptoms, they can interact with others but should wear a mask for the remaining five days.
For those who suspect they’ve been recently exposed, the CDC now recommends that people who are unvaccinated or who had received their primary vaccine series more than six months ago should quarantine for five days, then wear a mask for the remaining five days (ideally getting tested for covid-19 around day five). If they’re unable to quarantine, then they should wear a mask all 10 days. Lastly, for those exposed who have gotten all their shots, including a booster, they’re recommended to wear a mask for 10 days but don’t have to quarantine/isolate if they’re not experiencing symptoms.
There have been numerous studies suggesting that people are most infectious right before they get sick and for a few days afterward. Other research has shown that this window of infection may close even sooner for vaccinated people who develop a breakthrough infection. And in justifying the new guidance, the CDC did reference this data. “The change is motivated by science demonstrating that the majority of SARS-CoV-2 transmission occurs early in the course of illness, generally in the 1-2 days prior to onset of symptoms and the 2-3 days after,” the CDC wrote in its explanation of the changes Monday.
Yet, the evidence isn’t as cut-and-dry as the CDC makes it appear, according to Justin Feldman, a social epidemiologist at Harvard who has studied the disparate impacts of the pandemic within the U.S.
“The CDC’s move to shorten isolation to 5 days, with no requirement to test negative before going back to work, is reckless and dangerous,” Feldman told Gizmodo. “There is a lot of variability in how long people stay contagious, and many can still infect others after 5 days.”
Ellie Murray, an epidemiology professor at the Boston University School of Public Health, notes that the data cited by the CDC to warrant this change isn’t particularly ground-breaking. “Shortening the isolation period does not seem to be based on any new data about the virus or how it spreads, and epidemiologically there’s no new evidence to support this change. I do not think that it will help if the goal is to keep cases as low as possible,” she told Gizmodo.
Indeed, while some experts are generally supportive of the isolation period being made shorter, they’ve still been critical about the lack of advice for people to get tested before leaving isolation. The UK recently shortened its recommendations for isolation from 10 days to seven days for most people, but only if the person tests negative on two rapid lateral flow tests two days in a row. Strangely enough, the CDC did follow in the UK’s footsteps, but only for healthcare workers. As of last week, healthcare workers are now recommended to return to work after seven days, if they test negative and are asymptomatic; however, “isolation time can be cut further if there are staffing shortages.”
“It makes a great deal of sense to allow some people to leave isolation in fewer than 10 days,” Carl Bergstrom, a professor of biology at the University of Washington, told Gizmodo. “The devil is in the details though. How much fewer, and what precisely should be the criteria? The CDC press release doesn’t answer this.”
Adding to the confusion is that the five-day rule is ostensibly meant for people who are asymptomatic — in other words, not feeling sick at all. Yet on the same page explaining the change, the CDC later says that this also applies to people whose symptoms are “resolving” after five days. Those with fever, however, are still being told to isolate longer.
“For previous strains, the infectious period was considerably longer than five days in many though not all patients. Does the CDC believe that this is changed?” Bergstrom said. “Is the thought that vaccination or prior infection status reduces the infectious interval — and if so, should that be accounted for in the recommendation? Is this some kind of cost-benefit calculation? We aren’t given enough information to know.”
The elephant in the room is that these changes do not appear to be solely motivated by the science surrounding covid-19 transmission. Just a week ago, Delta Air Lines CEO Ed Bastian publicly pleaded with the CDC to cut the recommended isolation period for fully vaccinated people with breakthrough infections, citing the impacts it was having on his workforce. And many experts, along with workers’ unions, do believe that this is more about getting people to work than keeping others safe from covid-19.
“It is a clear case of prioritising corporate profit over public health, and it’s happening at a time when many hospitals are starting to become overwhelmed with covid-19 patients,” Feldman said.
Indeed, the country is in the midst of a resurgent wave of the pandemic, with case loads rising in some areas to the highest levels seen yet, fuelled by the emergence of the Omicron variant. And while Omicron does appear to be milder than the recently dominant Delta variant, it may not be any less of a problem than past strains of the coronavirus. Much like previous waves, it’s not just cases but hospitalizations and deaths that now appear to be on the rise.
It’s possible that this change may not affect the trajectory of the pandemic much, since people are generally less infectious after a few days. But it’s perhaps another example of the CDC losing the trust of the public in recent months (on social media, scientists and others are now parodying the CDC’s business-friendly advice). The new recommendations may also just be counterproductive, according to Murray, if you’re hoping to get everyone back to work as soon as possible.
“It seems very short-sighted to imagine that workplace absences are not going to be coupled to case levels. Workplaces being full of infectious employees will just mean more and more staffing issues,” she noted. “Accepting some closures now to get this surge under control would result in fewer staffing issues in January — if that’s really all they care about — and less covid.”
Editor’s Note: Release dates within this article are based in the U.S., but will be updated with local Australian dates as soon as we know more.