Just wanted to get a quick couple words out on the newest information related to Isolation and precautions during pandemic.
As we accumulate more evidence it is becoming apparent that prolonged isolation is not warranted, as approximately 10 days after symptom onset (non-severe cases), there is a decline in concentration of SARS-CoV-2 replication-competent virus. This information allows us to use a symptom-based strategy. Although, those patients with SEVERE illness may shed longer. At this time, mild to moderate symptomology should quarantine for 10 days post symptom onset and severe cases would isolate out to 20 days. Asymptomatics should isolate for 10 days post PCR positive test for SARS_CoV-2. This approach has an 88-95% confidence limit.
In another large contact tracing study it was shown that exposure to infected person after 6 days post start of infected patients symptoms did not cause the exposed to contract the virus. The interesting fact is that while replication-competent virus was not found in those who are infected. The virus can shed the from nasopharyngeal / upper respiratory tracts for 12 weeks, so even in those with redevelopment of symptoms it was not shown to have the replication competent virus necessary for transmission. In general reinfection is rare, but trends to occur with increased time from initial infection, or symptom onset (>3 months), likely due to waning immunity and genetic drift. As pandemic continues, we may see more reinfection, but those re-infected will not necessarily transmit virus, but most should under go infectious disease evaluation and re-isolate under certain circumstances.
This information strengthens the justification for relying on symptoms and not a test based strategy. This will allow unnecessary isolation and allow previously infected but symptom free patients to return to work and other responsibilities. Patients that continue to shed virus after their symptoms are not being found to be transmitters and this can take place for up to 90 days.
This information is ever evolving and we will need many years of data to determine correlates of immunity to SARS-CoV-2.
Duration of Isolation and Precautions
For most persons with COVID-19 illness, isolation and precautions can generally be discontinued 10 days after symptom onset 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.
Role of Viral Diagnostic Testing (PCR or Antigen) to Discontinue Isolation or Precautions
For persons who are severely immunocompromised, a test-based strategy could be considered in consultation with infectious diseases experts.
For all others, a test-based strategy is no longer recommended except to discontinue isolation or precautions earlier than would occur under the strategy outlined in Part 1, above.
Role of Viral Diagnostic Testing (PCR or Antigen) After Discontinuation of Isolation or Precautions
For persons previously diagnosed with symptomatic COVID-19 who remain asymptomatic after recovery, retesting is not recommended within 3 months after the date of symptom onset for the initial COVID-19 infection.
For persons who develop new symptoms consistent with COVID-19 during the 3 months after the date of initial symptom onset, if an alternative etiology cannot be identified by a provider, then the person may warrant retesting. Consultation with infectious disease or infection control experts is recommended, especially in the event symptoms develop within 14 days after close contact with an infected person. Persons being evaluated for reinfection with SARSCoV-2 should be isolated under recommended precautions while undergoing evaluation. If reinfection is confirmed or remains suspected they should remain under the recommended SARS-CoV-2 isolation until they meet the criteria for discontinuation of precautions – for most persons, this would be 10 days after symptom onset and resolution of fever for at least 24 hours, without the use of fever-reducing medications, and with improvement of other symptoms.
For persons who never developed symptoms, the date of first positive viral diagnostic test (PCR or antigen) for SARS-CoV-2 RNA should be used in place of the date of symptom onset.
Role of Serologic Testing
Serologic testing should not be used to establish the presence or absence of SARS-CoV-2 infection or reinfection.
 Symptom onset is defined as the date on which symptoms first began, including nonrespiratory symptoms.
 PCR testing is defined as the use of an RT-PCR assay to detect the presence of SARSCoV-2 RNA..