5 April 2020 Blog Post: Defining "Recovery"
One topic I have covered before in my Facebook posts is the idea of recovery from #COVID-19. In fact, the concept of recovery from coronavirus (and infectious diseases in general) actually has two parts to it. In the first, when has the individual patient ‘recovered’ in terms of symptoms and, in the second, when is that individual no longer able to infect others?
In the case of the common cold, this is a fairly easy answer. One is recovered when one is feeling better. But transmission of the virus, particularly in a crowded environment, can last for weeks. This was shown starkly in a study of US military recruits in 2006. Over the course of a 4-week period, researchers recorded an incredible 98% rate of adenovirus infection among 180 susceptible recruits.
With COVID-19 the definition of “recovery” is at yet unclear. According to Dr. Fukuda (Director School of Public Health at the University of Hong Kong) – “the difficulty is that some people who feel subjectively well still have laboratory and chest CT evidence of infection. When we have more information about the relationship of infection and symptoms for COVID, we will have a better idea of how to define ‘recovered’ for COVID-19.” For now, “we are still trying to determine what recovery means.”
OK that’s factually correct but practically unhelpful (and illustrates the essential reason I moved into clinical practice instead of laboratory epidemiology).
Further, early evidence suggests that coronavirus may lead to persistent health effects. In our own (limited) clinical experience with coronavirus cases, some patients have had persistent low grade fevers, fatigue and shortness of breath weeks after the initial onset of symptoms. In particular, the characteristic loss of taste and smell seems to extend for several weeks after the initial positive testing. Oh and the headaches. Don’t forget the headaches. Did I mention the fatigue? Also there is characteristic shortness of breath climbing a short flight of stairs or during a phone conversation. My usual ‘doctor line’ for a viral infection of a ‘week coming, a week with you and a week going’ is inadequate for COVID-19. It acts more like a clueless party guest who shows up 10 minutes early while you are still setting up and sticks around well after the festivities are done to watch you load the dishwasher.
In my clinical practice, the goal is to treat and care for coronavirus patients at home, keeping them out of the ER and hospital. For people with COVID-19 who are not hospitalized, the U.S. Centers for Disease Control and Prevention (CDC) provides symptoms-based criteria to determine whether they have “recovered” from the illness. Clinical criteria include not having a fever for 72 hours (without Tylenol), and when “other symptoms have improved,” like coughing and shortness of breath. The CDC also requires that they must also receive two negative tests in a row, 24 hours apart. If they do not have access to a test (which many do not have access to even a first test), the first two criteria remain, and they must also wait for seven days to pass since the onset of symptoms before they can stop home isolation. The Korean CDC criteria are more stringent. They require two weeks of quarantine after a positive test, then clinical improvement (absence of symptoms without use of Tylenol or other supportive care measures) along with two negative tests in a row (also 24 hours apart) at the end of the two weeks. If these tests remain positive, the patient can be retested. However, at the end of three weeks from the date of the first positive test, a patient regardless of test results is deemed “recovered” after three weeks of quarantine.
But let’s be honest, nobody actually knows the duration for which a person with COVID-19 is contagious. One study in Germany estimated it would take 10 days after patients with mild illness first fell sick for them to become low-risk for spreading the disease (note here that it is not ‘no risk’, simply low risk). Another study out of Wuhan, China, found that the virus could “live” in a recovered patient’s respiratory tract for anywhere from eight to 37 days. Given this finding, health officials in China mandate that recovered patients self-isolate for another two weeks after hospital discharge, just in case, and then get tested once more.
At Santa Monica Primary Care, we have attempted to formally define ‘recovery’ and are similarly perplexed. Consistent with the Wuhan study cited above, we do see persistently positive respiratory tract swabs at 2 weeks from initial positive testing. Are these simply bits and pieces of the chewed up viral genome or are they infectious?
The only way to truly know is to trace patients who have established clinical “recovery” and assess their risk to household and physically distanced contacts. A working group from the University of Washington Virology Department is working on a voluntary program called nextrace.org. It is not yet up and running but I am hopeful that efforts such as these will help quantify the relative risk that “recovered” coronavirus cases pose to the general public.
For a better written and more comprehensive discussion, from which portions of the above post were gleaned – please access: What does it mean to ‘recover’ from the coronavirus?
𝗦𝗶𝗴𝗻 𝗨𝗽 𝗳𝗼𝗿 𝗢𝘂𝗿 𝗡𝗲𝘄𝘀𝗹𝗲𝘁𝘁𝗲𝗿
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