Spread ’em! I mean please don’t spread ’em! AKA: COVID-19, Contagiousness, and Isolation Time
As a person in the field of medical education, my day-to-day personal life as a human being with an interest in COVID-19 (which is most of us) is colliding with my professional one as a medical educator. What to do? Take on a comprehensive FAQ compendium on COVID-19? Maybe …but not right now. Let’s start with some of the hot questions and myths out there in our new blog feature, “The COVID Corner.” The first topic I’d like to discuss is: “Who should be considered contagious for the SARS-CoV2 virus after exposure or development of COVID-19, and for how long?” Would it be safe to be around a person who had COVID-19 14 days after they developed symptoms? Maybe, but maybe not. According to the CDC, for people with mild-to-moderate symptoms, it’s safe to be around others:
- 10 days since the symptoms started AND
- 24 hours without fever (and without use of fever reducers) AND
- other COVID-19 symptoms are improving
But what about someone who had severe symptoms?
- Then it’s best for them to isolate up to 20 days after the symptoms first appeared (as well as meeting the other criteria).
But what about someone who was exposed to someone with COVID-19 (and was not symptomatic)?
- Local recommendations may vary, but that person should quarantine for 14 days after their last exposure to the person with COVID-19.
Should we just test everyone again before we consider them safe?
No. That’s not particularly helpful and uses precious testing resources. While some work places proposed a test-based strategy to determine who should come back to work/engage in normal activities after they have had COVID-19, this led to problems for some individuals who still tested positive for a long time after they truly recovered from the disease. Why would someone continue to test positive? Are they now silent asymptomatic spreaders? Not likely. The COVID-19 PCR test can detect the intact virus, but it also can recognize “pieces” of the virus. Recovered people may still have broken-up pieces of virus in their body. These are the viral bodies on the battlefield. However, recovered people typically do not have what is called “replication-competent virus.” That’s virus that’s intact and fully capable of reproducing itself and infecting someone else. So the test is not perfect in determining if someone is still contagious (ie, think replication-competent virus). SOURCE: https://www.cdc.gov/coronavirus/2019-ncov/hcp/return-to-work.html
Then how do we trust those isolation times?
The CDC recommendations on “wait” times ARE based on real studies that tracked the so-called replication-competent virus in individuals with COVID-19 symptoms. Let’s just say this is pretty challenging cell culture stuff with a nasty virus—do not try this at home. Anyway, for people who had mild-to-moderate disease, the researchers were not able to recover replication-competent virus 10 days after symptoms started. For people with severe disease, it was a no go for replication-competent virus after 20 days. So these times are the real deal—they measured a meaningful end point and came up with a specific time period. Of course, if you are immunocompromised or have other concerns, please talk with your healthcare provider—it may affect how long you need to isolate. But now you know that those “waiting period” recommendations did not come out of thin air. SOURCE: https://www.cdc.gov/coronavirus/2019-ncov/hcp/duration-isolation.html