How long should my patient recovering from Covid-19 remain on isolation precautions?

For the great majority of patients with Covid-19, the risk of shedding viable SARS-CoV2 diminishes considerably as the time from onset of symptoms nears 10 days or more, with the risk higher among those who have severe (eg, sp02 <94%)  or critical disease (eg, in need of ICU care) or who are immunocompromised. 1-4  

For patients with mild-moderate illness who are not immunocompromised, the CDC recommends isolation for “at least 10 days” from onset of symptoms as long as at least 24 hours have passed since last fever without the use of fever-reducing medications and symptoms  (eg, cough, shortness of breath) have improved.  For patients with severe to critical illness or who are severely immunocompromised, “at least 10 days” and up to 20 days since onset of symptoms—with qualifications as above— is recommended. 1

A 2021 meta-analysis found that although SARS-CoV-2 RNA shedding in respiratory and stool samples may be prolonged, duration of viable virus was relatively short with no study detecting live virus beyond day 9 of illness.2

In contrast, another study involving patients with severe or critical illness (23% immunocompromised, 2/3 on mechanical ventilation) found  that the median time of infectious virus shedding was 8 days (range 0-20) and concluded that detection of infectious virus was common after 8 days or more since onset of symptoms; the probability of isolating infectious SARS-CoV-2 was  ≤5% when the duration of symptoms was 15.2 days (95% CI 13.4-17.2). In the same study, a single patient had infectious particles for up to 20 days following onset of symptoms. 3

The take home point is that although 10 days of isolation since onset of symptoms should be sufficient for mild to moderate Covid-19, for those with severe or critical disease or immunocompromised state, a longer duration up to 20 days may be needed.  The setting and status of the potential contacts (eg, an immunocompromised person in household setting) should also be considered in our decision making. 4

Bonus Pearl: Did you know that infectious particles are unlikely to be isolated from respiratory tract samples once patients develop a serum neutralizing antibody titer of at least 1:80, potentially useful information in deciding when a patient may come off isolation? 3

Liked this post? Download the app on your smart phone and sign up below to catch future pearls right into your inbox, all for free!

Subscribe to Blog via Email

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

 

References

  1. Discontinuation of transmission-based precautions and disposition of patients with SARS-CoV-2 infection in healthcare settings. https://www.cdc.gov/coronavirus/2019-ncov/hcp/disposition-hospitalized-patients.html#definitions. Accessed March 24, 2021
  2. Cevik M, Tate M, Lloyd O, et al. Sars-Cov-2, SARS-CoV, and MERS-CoV viral load dynamics, duration of viral shedding, and infectiousness: a systematic review and meta-analysis. Lancet Microbe 2021;2:e13-22. https://www.thelancet.com/pdfs/journals/lanmic/PIIS2666-5247(20)30172-5.pdf
  3. Van Kampen JJA, van de Vijver DAMC, Fraaij PLA, et al. Duration and key determinants of infectious virus shedding in hospitalized patients with coronavirus disease-2019 (COVID-19). Nature Communications 2021;12:267. https://www.nature.com/articles/s41467-020-20568-4
  4. Kadire SR, Fabre V, Wenzel RP. Doctor, how long should I isolate? NEJM, March 2021 https://www.nejm.org/doi/pdf/10.1056/NEJMclde2100910?articleTools=true

 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

How long should my patient recovering from Covid-19 remain on isolation precautions?

What’s the evidence that patients with Covid-19 are at high risk of blood clots?

Although we often think of it as a respiratory disease, emerging evidence suggests that Covid-19, particularly when severe,  is also associated with high risk of thrombotic events, including pulmonary embolism, venous thrombosis, and arterial thrombotic events.1

A Chinese study found that ICU patients with severe Covid-19 had a venous thromboembolism (VTE) incidence of 25%, with disseminated intravascular coagulopathy (DIC) found in the majority of fatal cases.2

A prospective Dutch study involving critically ill ICU patients with Covid-19 reported VTE in 27% and arterial thrombotic events in another 3.7%, despite standard VTE prophylaxis.3 The authors suggested the use of “high prophylactic doses” of anticoagulants in these patients due to concern over hypercoagulability.

An ICU French study also found high frequency of thrombotic complications in Covid-19 patients with ARDS, with 11.7% of patients having pulmonary embolism vs 2.1% in non-Covid-19 patients with ARDS. As with the Dutch study, thrombotic complications occurred despite standard prophylactic anticoagulation.4

Postmortem studies have also shown marked changes in lung microvasculature with the presence of microthrombi, with some calling it “pulmonary intravascular coagulopathy” to distinguish it from DIC.1

A NEJM letter reported 5 Covid-19 patients less than 50 years of age who presented with large vessel stroke symptoms without an alternative explanation.5 Of interest, 2 of these patients had no other symptoms suggestive of Covid-19.  A pre-print article from China reported an acute stroke incidence of 5% in hospitalized patients with Covid-19.6

The finding of a hypercoagulable state in patients with severe Covid-19 is not surprising given the frequent association of this infection with a high inflammatory state and the well-known capability of SARS-CoV-2 to attack the endothelial surfaces of blood vessels. High inflammatory state can promote activation of blood coagulation through release of inflammatory cytokines (eg, IL-6, IL-8, and TNF-alpha).1

Perhaps even more intriguing is the finding of extremely high levels of factor VIII found in some Covid-19 patients which could make them hypercoagulable.7 This phenomenon should be suspected when a patient appears to be resistant to anticoagulation by heparin based on aPTT but not based on anti-Xa assay.7

 Bonus pearl: Did you know that the overall incidence of VTE is lowest among Asians-Pacific islanders, followed by Hispanics and Caucasians, with highest rate among African-Americans? 1 ,8

Liked this post? Download the app on your smart phone and sign up below to catch future pearls right into your inbox, all for free!

Subscribe to Blog via Email

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

References

  1. Fogarty H, Townsend L, Cheallaigh CN, et al. COVID-19 coagulopathy in Caucasian patients. Br J Haematol 2020, https://onlinelibrary.wiley.com/doi/epdf/10.1111/bjh.16749
  2. Cui S, Chen S, Li X, et al. Huang C, Wang Y, Li X, et al. Prevalence of venous thromboembolism in patients with severe novel coronavirus pneumonia. J Thromb Haematol 2020, April 9. https://onlinelibrary.wiley.com/doi/epdf/10.1111/jth.14830
  3. Klok FA, Kruip MJHA, van der Meer NJM, et al. Incidence of thrombotic complications in critically ill ICU patients with COVID-19. Thromb Res 2020. https://www.sciencedirect.com/science/article/pii/S0049384820301201?via%3Dihub
  4. Helms J, Tacquard C, Severac F, et al. High risk of thrombosis in patients in severe SARS-CoV-2 infection: a multicenter prospective cohort study. Intensive Care Med 2020; https://www.esicm.org/wp-content/uploads/2020/04/863_author_proof.pdf
  5. Oxley TJ, Mocco J, Majidie S, et al. Large-vessel stroke as a presenting feature of Covid-19 in the young. N Engl J Med. 2020, April 28. https://www.nejm.org/doi/full/10.1056/NEJMc2009787?query=featured_home
  6. Li Y, Wang M. Acute cerebrovascular disease following COVID-19: A single center, retrospective, observational study. 2020. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3550025
  7. Beun R, Kusadasi N, Sikma M, et al. Thromboembolic events and apparent heparin resistance in patients infected with SARS-CoV-2. Int J Lab Hematol 2020, April 20. https://onlinelibrary.wiley.com/doi/abs/10.1111/ijlh.13230
  8. White RH, Keenan CR. Effects of race and ethnicity on the incidence of venous thromboembolism. Thromb Res 2009;123 Suppl 4:S11-S17. doi:10.1016/S0049-3848(09)70136-7

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Massachusetts General Hospital, Harvard Catalyst, Harvard University, its affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

What’s the evidence that patients with Covid-19 are at high risk of blood clots?