The mounting scientific evidence now indicates that this virus is very unlikely to be transmissible after about 10 days (from the time symptoms begin). Individuals who experienced severe infection (with an immunocompromised state) may be able to transmit the virus for 10-20 days, however, it was estimated that around 90% of their specimens no longer yielded virus that could be infective after approximately 10-15 days. Thus, even those patients are exceedingly unlikely to infect others after about 10 days from symptom onset.
In support of these findings, a large contact tracing study demonstrated that contacts from high-risk households and hospitals did not develop infection if their exposure to a Covid patient started 6 days or more after symptom onset (Cheng et al., 2020).
It is important to note that viral PCR testing may still be positive for up to 3 months due to the presence of weakened viral particles that are no longer infectious. For this reason PCR testing is no longer recommended to determine whether a covid patient is still infectious.
With regard to re-infection of the coronavirus, there is no evidence yet that this has actually occurred. However, the scientific community is concerned about this potential, given that the data remains limited from some of the regions where sustained infection pressure has been highest. I am personally optimistic about this concern, given that we are 6 months into the pandemic and still have not a single confirmed case of re-infection. People who are immunocompromised may not be able to mount a normal immune response to protect them from re-infection, and should therefore consider (together with their medical team) ongoing preventative measures. Such measures could include proper nutrition, sufficient sleep, stress management, and certain medications, such as antivirals or even a prophylactic ultra low-dose of hydroxychloroquine, as well as immunization as soon as a vaccine is available. [It should be noted that the literature found high-dose hydroxychloroquine to have significant cardiovascular risks, yet a very low dose may provide some protection without the risk.]
Abbreviated CDC Recommendations
- Duration of isolation and precautions
- For most persons with COVID-19 illness, isolation and precautions can generally be discontinued 10 days after symptom onset.
- For persons who never develop symptoms, isolation and other precautions can be discontinued 10 days after the date of their first positive PCR test for SARS-CoV-2 RNA.
- Role of PCR testing to discontinue isolation or precautions
- 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.
- For persons who are severely immunocompromised, a test-based strategy could be considered in consultation with infectious diseases experts.
- Role of PCR testing after discontinuation of isolation or precautions
- For persons who never developed symptoms, the date of first positive RT-PCR test for SARS-CoV-2 RNA should be used in place of the date of symptom onset.
- 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 cause of the symptoms cannot be identified, then the situation may warrant retesting. Isolation may be considered during this evaluation based on consultation with an infection control expert, especially in the event symptoms develop within 14 days after close contact with an infected person.
- Role of serologic testing
- Serologic testing should not be used to establish the presence or absence of SARS-CoV-2 infection or reinfection.
Well, there you have it — It is officially considered “safe” to be in the presence of anyone who has recovered from Covid symptoms starting 10 days after the date in which symptoms first began, or 10 days from the date of the first positive test. In the case of individuals who experienced severe Covid infection (or immunocompromised patients) there is no clear number of days recommended, but the data indicate that 15 days should be sufficient in most cases, and 20 days may be even safer.
When it comes to Covid-19 nobody is an expert, so please post questions or comments that can enhance our knowledge and generally help the PAA community. We are not interested in conspiracy theories or political rhetoric on this website, so please stick to scientifically published facts and sincere questions. If you are confused about something you read on the internet that you’d like to get information about from an unbiased source, we’d be happy to try to help clear things up for you.
Justin Groode MD | Patient Advocate Alliance, LLC
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