On Wednesday, April 15th, I tested positive for COVID-19. Trying to be a good citizen and not infect anyone with a dangerous virus, I looked up the CDC isolation guidelines. Instead of finding certainty, I found a hot scientific controversy.
The CDC Guideline:
On December 27, 2021, the CDC updated its COVID isolation guidelines, stating: “Given what we currently know about COVID-19 and the Omicron variant, CDC is shortening the recommended time for isolation for the public. People with COVID-19 should isolate for 5 days and if they are asymptomatic or their symptoms are resolving (without fever for 24 hours), follow that by 5 days of wearing a mask when around others to minimize the risk of infecting people they encounter. 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.”
A Fierce Pushback:
Almost immediately, the CDC’s recommendation was criticized by respected faces in the public health and medical communities. On Jan 5, 2022, the President of the American Medical Association, Gerald E. Harmon, MD, wrote: “According to the CDC’s own rationale for shortened isolation periods for the general public, an estimated 31 percent of people remain infectious 5 days after a positive COVID-19 test…A negative test should be required for ending isolation after one tests positive for COVID-19. Reemerging without knowing one’s status unnecessarily risks further transmission of the virus.” Similarly, Michael Mina, an epidemiologist, physician, and Chief Scientific Officer at eMed (previously faculty at Harvard) tweeted that, "CDC's new guidance to drop isolation of positives to 5 days without a negative test is reckless.” It is worth clarifying that Mina was arguing for using rapid antigen tests, which are a fairly good barometer of infectiousness, rather than PCR tests, which can return a positive result long after a person is no longer infectious.
Mina was particularly frustrated that the CDC stated 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,” since this data was collected prior to the Omicron variant’s emergence as the dominant COVID variant. Mina wrote: “Today, it is OBVIOUS the situation has changed. Ppl are testing earlier b/c symptom onset is early - no longer two days after people are infectious. So now people are staying positive even longer after testing positive, because they find out earlier they are positive. And by positive I don't mean PCR positive. I mean rapid antigen test positive for days longer. Often more than 10 days. So to say, leave isolation regardless of if you have a positive antigen test is remarkable. Someone KNOWN to be Pos for 5 days is, in my view, still one of the highest risk individuals in society for onward spread. We do SO much just to find ppl who are positive in first place. When we do identify them, we should do everything possible to keep them from spreading.”
Did Test Scarcity Shape The Guidelines?
Many critics have pointed to the lack of availability of rapid tests (and tests in general) in the midst of the Omicron surge in late December as potentially driving the CDC’s policy decision not to recommend a negative test prior to exiting isolation, a dynamic Dr. Celine Gounder described as an "example of scarcity determining policy”. Relatedly, at the time some experts who supported the decision viewed it as having been “necessary to prevent collapse of critical infrastructure”, presumably because if the Omicron wave led to too many people isolating for overlapping periods, hospitals would run out of nurses, airlines would run out of flight attendants, and other services necessary for ordinary functioning of both the health system and the broader economy would be severely disrupted. Too many people waiting to test out of quarantine because of scarce antigen tests could exacerbate the problem. While CDC Director Dr. Walensky has not made this argument explicitly as far as I am aware, perhaps it could help explain why the CDC’s decided in late December to not ask people to receive a negative antigen test before ending their isolation. However, if antigen test scarcity really did shape the guideline, one has to ask: why didn’t the CDC update the guideline once the winter Omicron surge ebbed and antigen tests became widely available? Is the CDC concerned that admitting that test scarcity influenced the isolation guideline announcement in December 2021 would implicitly undermine the CDC’s credibility and further entrench public skepticism that CDC is not a purely scientific agency? Of course, whether CDC wants to be or not, it is also effectively a policy-making agency in addition to a scientific one, with all of the difficult tradeoffs that entails. While I know there are surely counterarguments, I suspect the public might be better served and might trust the CDC more if the agency were to openly acknowledge that it performs both purely scientific and policymaking roles, and behave accordingly.
My Takeaway:
I don’t blame people for throwing up their hands at this admittedly confusing situation and saying “If it’s good enough for the CDC, it’s good enough for me”. That is, of course, partly why the CDC exists-to offer science-based public health recommendations that the public can take to the bank, without needing to play epidemiologist in their free time. Nevertheless, I disagree with the CDC guideline. With a virus as transmissible and frequently fatal as the Omicron variant of COVID-19, I think we should all make sure to receive a negative antigen rapid test before ending our isolation, lest we unwittingly contribute to the virus’ devastating toll.
Excellent post! I would add that CDC and this administration generally have been MIA with regard to informing the public and designing policy around the risk of long covid, which in the best case scenario may affect 10% of the 500 million+ people globally who have survived covid infection. That vaccinated people with mild illness may still be at risk (~3% based on a VA study) makes the prospect of persistent illness that includes disabling fatigue and cognitive an extremely serious public health issue. This country and the first world have yet to take the enormous personal and societal burden of long covid seriously. Wearing well-fitting N95 masks indoor would be a great first step but ppl cannot be expected to make this decision on their own.