Coronavirus Illness 2019 (COVID-19)


Abstract of Current Modifications

As of October 19, 2020

  • Added standards and proof to handle whether or not individuals who recovered from COVID-19 and are re-exposed to COVID-19 must bear repeat quarantine.

Accumulating proof helps ending isolation and precautions for individuals with COVID-19 utilizing a symptom-based technique. This replace incorporates latest proof to tell the period of isolation and precautions really useful to forestall transmission of SARS-CoV-2 to others, whereas limiting pointless extended isolation and pointless use of laboratory testing assets.

Key findings are summarized right here.

  1. Concentrations of SARS-CoV-2 RNA measured in higher respiratory specimens decline after onset of signs (CDC, unpublished information, 2020; Midgley et al., 2020; Younger et al., 2020; Zou et al., 2020; Wölfel et al., 2020; van Kampen et al., 2020).
  2. The chance of recovering replication-competent virus additionally declines after onset of signs. For sufferers with delicate to average COVID-19, replication-competent virus has not been recovered after 10 days following symptom onset (CDC, unpublished information, 2020; Wölfel et al., 2020; Arons et al., 2020; Bullard et al., 2020; Lu et al., 2020; private communication with Younger et al., 2020; Korea CDC, 2020). Restoration of replication-competent virus between 10 and 20 days after symptom onset has been documented in some individuals with extreme COVID-19 that, in some circumstances, was sophisticated by immunocompromised state (van Kampen et al., 2020). Nonetheless, on this sequence of sufferers, it was estimated that 88% and 95% of their specimens now not yielded replication-competent virus after 10 and 15 days, respectively, following symptom onset.
  3. A big contact tracing examine demonstrated that high-risk family and hospital contacts didn’t develop an infection if their publicity to a case affected person began 6 days or extra after the case affected person’s sickness onset (Cheng et al., 2020).
  4. Though replication-competent virus was not remoted 3 weeks after symptom onset, recovered sufferers can proceed to have SARS-CoV-2 RNA detected of their higher respiratory specimens for as much as 12 weeks (Korea CDC, 2020; Li et al., 2020; Xiao et al, 2020). Investigation of 285 “persistently constructive” individuals, which included 126 individuals who had developed recurrent signs, discovered no secondary infections amongst 790 contacts attributable to contact with these case sufferers. Efforts to isolate replication-competent virus from 108 of those case sufferers have been unsuccessful (Korea CDC, 2020).
  5. Specimens from sufferers who recovered from an preliminary COVID-19 sickness and subsequently developed new signs and retested constructive by RT-PCR didn’t have replication-competent virus detected (Korea CDC, 2020; Lu et al., 2020). The danger of reinfection could also be decrease within the first 3 months after preliminary an infection, based mostly on restricted proof from one other betacoronavirus (HCoV-OC43), the genus to which SARS-CoV-2 belongs (Kiyuka et al, 2018).
  6. To this point, reviews of reinfection have been rare. Just like different human coronaviruses the place research have demonstrated reinfection, the likelihood of SARS-CoV-2 reinfection is anticipated to extend with time after restoration from preliminary an infection on account of waning immunity and presumably genetic drift. Danger of reinfection will depend on the chance of re-exposure to infectious circumstances of COVID-19. Because the COVID-19 pandemic continues, we count on to see extra circumstances of reinfection.

The present proof contains the next caveats:

  • In a latest examine of expert nursing facility employees adopted prospectively for asymptomatic an infection, one in every of 48 contaminated workers had a nasopharyngeal swab which was weakly constructive on a single-passage plaque assay greater than 20 days after preliminary analysis; nevertheless, the specimen was not subjected to serial passage to exhibit the presence of replication-competent virus (Quicke et al., 2020).
  • In a single case report, an individual with delicate sickness supplied specimens that yielded replication-competent virus for as much as 18 days after symptom onset (Liu et al., 2020).
  • Information at present accessible are derived from adults; equal information from youngsters and infants should not presently accessible.
  • Extra information are wanted regarding viral shedding in some conditions, together with in immunocompromised individuals.


Out there information point out that individuals with delicate to average COVID-19 stay infectious now not than 10 days after symptom onset. Individuals with extra extreme to vital sickness or extreme immunocompromise possible stay infectious now not than 20 days after symptom onset.  Recovered individuals can proceed to shed detectable SARS-CoV-2 RNA in higher respiratory specimens for as much as 3 months after sickness onset, albeit at concentrations significantly decrease than throughout sickness, in ranges the place replication-competent virus has not been reliably recovered and infectiousness is unlikely. The etiology of this persistently detectable SARS-CoV-2 RNA has but to be decided. Research haven’t discovered proof that clinically recovered individuals with persistence of viral RNA have transmitted SARS-CoV-2 to others. These findings strengthen the justification for counting on a symptom based mostly, slightly than test-based technique for ending isolation of those sufferers, in order that individuals who’re by present proof now not infectious should not stored unnecessarily remoted and excluded from work or different obligations.

The period and robustness of immunity to SARS-CoV-2 stays below investigation. Primarily based on what we all know from different associated human coronaviruses, individuals seem to turn into vulnerable to reinfection round 90 days after onset of an infection. To this point, reinfection seems to be unusual through the preliminary 90 days after symptom onset of the previous an infection (Annex: Quarantine of Individuals Recovered from Laboratory-diagnosed SARS-CoV-2 An infection with Subsequent Re-Publicity). Thus, for individuals recovered from SARS-CoV-2 an infection, a constructive PCR with out new signs through the 90 days after sickness onset extra possible represents persistent shedding of viral RNA than reinfection.

  • If such an individual stays asymptomatic throughout this 90-day interval, then any re-testing is unlikely to yield helpful info, even when the particular person had shut contact with an contaminated particular person.
  • If such an individual turns into symptomatic throughout this 90-day interval and an analysis fails to determine a analysis aside from SARS-CoV-2 an infection (e.g., influenza), then the particular person could warrant analysis for SARS-CoV-2 reinfection in session with an infectious illness or an infection management professional. Isolation could also be warranted throughout this analysis, significantly if signs developed after shut contact with an contaminated particular person.

Correlates of immunity to SARS-CoV-2 an infection haven’t been established. Particularly, the utility of serologic testing to ascertain the absence or presence of an infection or reinfection stays undefined.

The suggestions under are based mostly on one of the best info accessible in mid-July 2020 and mirror the realities of an evolving pandemic. Even for pathogens for which a few years of knowledge can be found, it will not be potential to ascertain suggestions that guarantee 100% of individuals who’re shedding replication-competent virus stay remoted. CDC will proceed to intently monitor the evolving science for info that may warrant reconsideration of those suggestions.


  1. Period of isolation and precautions
    • For many individuals with COVID-19 sickness, isolation and precautions can typically be discontinued 10 days after symptom onset1 and determination of fever for not less than 24 hours, with out the usage of fever-reducing drugs, and with enchancment of different signs.
      • A restricted variety of individuals with extreme sickness could produce replication-competent virus past 10 days which will warrant extending period of isolation and precautions for as much as 20 days after symptom onset; contemplate session with an infection management consultants.
    • For individuals who by no means develop signs, isolation and different precautions may be discontinued 10 days after the date of their first constructive RT-PCR check for SARS-CoV-2 RNA.
  2. Function of viral diagnostic testing (PCR or antigen)2 to discontinue isolation or precautions
    • For individuals who’re severely immunocompromised, a test-based technique may very well be thought of in session with infectious ailments consultants.
    • For all others, a test-based technique is now not really useful besides to discontinue isolation or precautions sooner than would happen below the technique outlined in Half 1, above.
  3. Function of viral diagnostic testing (PCR or antigen)2 after discontinuation of isolation or precautions
    • For individuals beforehand recognized with symptomatic COVID-19 who stay asymptomatic after restoration, retesting just isn’t really useful inside 3 months after the date of symptom onset for the preliminary COVID-19 an infection.
    • For individuals who develop new signs in keeping with COVID-19 through the 3 months after the date of preliminary symptom onset, if an alternate etiology can’t be recognized by a supplier, then the particular person could warrant retesting. Session with infectious illness or an infection management consultants is really useful, particularly within the occasion signs develop inside 14 days after shut contact with an contaminated particular person. Individuals being evaluated for reinfection with SARS-CoV-2 ought to be remoted below really useful precautions whereas present process analysis. If reinfection is confirmed or stays suspected they need to stay below the really useful SARS-CoV-2 isolation till they meet the factors for discontinuation of precautions – for many individuals, this may be 10 days after symptom onset and determination of fever for not less than 24 hours, with out the usage of fever-reducing drugs, and with enchancment of different signs.
    • For individuals who by no means developed signs, the date of first constructive viral diagnostic check (PCR or antigen) for SARS-CoV-2 RNA ought to be used rather than the date of symptom onset.
  4. Function of serologic testing
    • Serologic testing shouldn’t be used to ascertain the presence or absence of SARS-CoV-2 an infection or reinfection.

[1] Symptom onset is outlined because the date on which signs first started, together with non-respiratory signs.
[2] PCR testing is outlined as the usage of an RT-PCR assay to detect the presence of SARS-CoV-2 RNA..


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