1/n: Something that became quite clear to me after reading @JustinLessler et al's Lancet Inf. Dis. paper: if contact tracing should work, we will need to isolate contacts before PCR turns positive.
#COVIDー19 #SARS_COV_2
thelancet.com/journals/lanin…
#COVIDー19 #SARS_COV_2
thelancet.com/journals/lanin…
2/n: Patients who were identified based on symptoms were diagnosed 4.6 days after symptom onset, whereas patients who were identified through contact tracing had a positive PCR test 2.9 days after symptom onset. 
3/n: As we've learned from @gmleunghku et al., most infections have already occurred at 4.6 days and 2.9 days after symptom onset. Infectiousness is marked yellow in the attached images.
nature.com/articles/s4159…
nature.com/articles/s4159…
4/n: We'll have to...
A) isolate high-risk contacts immediately after symptom onset in the index case and
B) we'll likely need an app to greatly shorten the time delay between symptom onset in the index case to isolation in their contacts. As described by @ChristoPhraser
A) isolate high-risk contacts immediately after symptom onset in the index case and
B) we'll likely need an app to greatly shorten the time delay between symptom onset in the index case to isolation in their contacts. As described by @ChristoPhraser
5/5: @threadreaderapp unroll
You can download the PDF version of the unroll here: dropbox.com/s/5mqt5enne81e…
