1/ It's becoming clearer that 10 days of isolation for severe COVID is not sufficient.
In this study, virus was cultured from predominantly NP samples 3-4 weeks after symptom onset. Only 7 of the 87 patients with severe disease were admitted to ICU (i.e. most were on the ward).
2/ Here's another preprint suggesting persistently high viral load in LRT samples through to 10 days following symptom onset (the period sampled though it seems reasonable to extrapolate beyond this given no downward trend) in severe disease:
4/ But @PublicHealthON IPAC guidelines are incongruent with this, and lump hospitalized patients in with "mild to moderate" disease, for which only 10 days of isolation precautions are recommended.
6/ ... and increasing prevalence of B.1.1.7, I think we urgently need to update the @PublicHealthON guidelines on duration of isolation precautions for ward patients requiring supplemental O2, who should be considered "severe" for this purpose in alignment with the literature.
Circling back to clarify that this study included similar numbers of "severe illness" and "critical illness" per NIH definitions, which were collectively analyzed as "severe disease" (vs "non-severe disease," which included asymptomatic, mild, and moderate illness).
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I wish I had a bigger follow to promote this paper because I think this kind of research is so important. I just joined twitter, so I don't, but I'll try to do my part anyway. Have a look at: medrxiv.org/content/10.110…
They found that HCWs were identified as cases of COVID at a rate 5.5x nonHCWs (range 2-6 mirroring the epidemic curve), and that 9.8% of HCWs likely transmitted to a household contact. Lots of other stuff in here but these were the findings I found most interesting.
I don't think the available data allowed them to adjust for a differential rate of testing, which was almost certainly higher among HCWs, though I doubt 5.5x higher. On the other hand, the denominator used to calculate rates of identified cases in HCWs was probably over-inclusive