Date: July 29, 2020
“Accumulating evidence supports ending isolation and precautions for persons with COVID-19 using a symptom-based strategy. This update incorporates recent evidence to inform the duration of isolation and precautions recommended to prevent transmission of SARS-CoV-2 to others, while limiting unnecessary prolonged isolation and unnecessary use of laboratory testing resources.
Key findings are summarized here.
Concentrations of SARS-CoV-2 RNA measured in upper respiratory specimens decline after onset of symptoms (CDC, unpublished data, 2020; Midgley et al., 2020; Young et al., 2020; Zou et al., 2020; Wölfel et al., 2020; van Kampen et al., 2020).
The likelihood of recovering replication-competent virus also declines after onset of symptoms. For patients with mild to moderate COVID-19, replication-competent virus has not been recovered after 10 days following symptom onset (CDC, unpublished data, 2020; Wölfel et al., 2020; Arons et al., 2020; Bullard et al., 2020; Lu et al., 2020; personal communication with Young et al., 2020; Korea CDC, 2020). Recovery of replication-competent virus between 10 and 20 days after symptom onset has been documented in some persons with severe COVID-19 that, in some cases, was complicated by immunocompromised state (van Kampen et al., 2020). However, in this series of patients, it was estimated that 88% and 95% of their specimens no longer yielded replication-competent virus after 10 and 15 days, respectively, following symptom onset.
A large contact tracing study demonstrated that high-risk household and hospital contacts did not develop infection if their exposure to a case patient started 6 days or more after the case patient’s illness onset (Cheng et al., 2020).
Although replication-competent virus was not isolated 3 weeks after symptom onset, recovered patients can continue to have SARS-CoV-2 RNA detected in their upper respiratory specimens for up to 12 weeks (Korea CDC, 2020; Li et al., 2020; Xiao et al, 2020). Investigation of 285 “persistently positive” persons, which included 126 persons who had developed recurrent symptoms, found no secondary infections among 790 contacts attributable to contact with these case patients. Efforts to isolate replication-competent virus from 108 of these case patients were unsuccessful (Korea CDC, 2020).
Specimens from patients who recovered from an initial COVID-19 illness and subsequently developed new symptoms and retested positive by RT-PCR did not have replication-competent virus detected (Korea CDC, 2020; Lu et al., 2020). The risk of reinfection may be lower in the first 3 months after initial infection, based on limited evidence from another betacoronavirus (HCoV-OC43), the genus to which SARS-CoV-2 belongs (Kiyuka et al, 2018).
Currently, 6 months after the emergence of SARS-CoV-2, there have been no confirmed cases of SARS-CoV-2 reinfection. However, the number of areas where sustained infection pressure has been maintained, and therefore reinfections would be most likely observed, remains limited.
Serologic or other correlates of immunity have not yet been established…
…Available data indicate that persons with mild to moderate COVID-19 remain infectious no longer than 10 days after symptom onset. Persons with more severe to critical illness or severe immunocompromise likely remain infectious no longer than 20 days after symptom onset. Recovered persons can continue to shed detectable SARS-CoV-2 RNA in upper respiratory specimens for up to 3 months after illness onset, albeit at concentrations considerably lower than during illness, in ranges where replication-competent virus has not been reliably recovered and infectiousness is unlikely. The etiology of this persistently detectable SARS-CoV-2 RNA has yet to be determined. Studies have not found evidence that clinically recovered persons with persistence of viral RNA have transmitted SARS-CoV-2 to others. These findings strengthen the justification for relying on a symptom based, rather than test-based strategy for ending isolation of these patients, so that persons who are by current evidence no longer infectious are not kept unnecessarily isolated and excluded from work or other responsibilities.
Reinfection with SARS-CoV-2 has not yet been definitively confirmed in any recovered persons to date. If, and if so when, persons can be reinfected with SARS-CoV-2 remains unknown and is a subject of investigation. Persons infected with related endemic human betacoronavirus appear to become susceptible again at around 90 days after onset of infection. Thus, for persons recovered from SARS-CoV-2 infection, a positive PCR during the 90 days after illness onset more likely represents persistent shedding of viral RNA than reinfection.
If such a person remains asymptomatic during this 90-day period, then any re-testing is unlikely to yield useful information, even if the person had close contact with an infected person.
Correlates of immunity to SARS-CoV-2 infection have not been established. Specifically, the utility of serologic testing to establish the absence or presence of infection or reinfection remains undefined.
The recommendations below are based on the best information available in mid-July 2020 and reflect the realities of an evolving pandemic. Even for pathogens for which many years of data are available, it may not be possible to establish recommendations that ensure 100% of persons who are shedding replication-competent virus remain isolated. CDC will continue to closely monitor the evolving science for information that would warrant reconsideration of these recommendations.
Duration of isolation and precautions
For most persons with COVID-19 illness, isolation and precautions can generally be discontinued 10 days after symptom onset1 and resolution of fever for at least 24 hours, without the use of fever-reducing medications, and with improvement of other symptoms.
A limited number of persons with severe illness may produce replication-competent virus beyond 10 days that may warrant extending duration of isolation and precautions for up to 20 days after symptom onset; consider consultation with infection control experts.
For persons who never develop symptoms, isolation and other precautions can be discontinued 10 days after the date of their first positive RT-PCR test for SARS-CoV-2 RNA.”
Speaking as someone who’s had a lifetime of health issues, and who’s taken this Covid 19 thing fairly serious…
…I have to confess…at this point in time…being someone who’s been forced out there “on the front lines” as an essential worker…and being someone who’s fairly clearly had this illness [my cyclical symptoms have matched what the experts have been describing]…and knowing that my last relapse with this was something like six months ago [or longer]…and realizing [if you believe the CDC] that they are [and have been] telling us, that most of us are only contagious for about ten days, after which we cannot pass it on…and even the more serious cases, they only estimate a 20 day period…
…I’m getting really, really, really fed up with being forced to wear a mask, and endlessly breathe in hot air for 8 hours a day…at a physically demanding job…in the middle of the hottest summer on record…knowing fully well, that it is almost certainly doing nothing, other than providing “comforting” optics and public relations…
Everything we know about this virus, is telling us that someone like myself is no longer even contagious…That ship has sailed…a long long time ago…
…And the ridiculous joke in all of this…is that we were all left hanging, out in the open…without any kind of warning about it already being here…or that a lot of us were already carrying and going through it…potentially passing it along to other people, without knowing anything about it…But now that we are six months [or longer] removed from being a danger, we get subjected to mandatory mask wearing…and various legal/employment threats, if we don’t comply.
This whole mess has been so badly bungled…that “the powers that be” are turning even someone like me, into an outraged and angry protestor.
They keep telling us “protect the vulnerable, who’ve yet to be infected”…but does this sanely apply to those of us, who aren’t even contagious anymore?