THREAD
1/ This study is important. They looked into false negative rates of PCR for #covid19 the days leading up to symptoms.
Even up to the day before symptoms start, the probability of a false-negative result is 67% (CI is wide, 27% to 94%).
acpjournals.org/doi/10.7326/M2…
1/ This study is important. They looked into false negative rates of PCR for #covid19 the days leading up to symptoms.
Even up to the day before symptoms start, the probability of a false-negative result is 67% (CI is wide, 27% to 94%).
acpjournals.org/doi/10.7326/M2…
2/ This matters because #SARSCoV2 viral load has been shown to peak on the day of symptom onset.
Presymptomatic transmission is estimated to account for nearly half of the transmission burden.
nature.com/articles/s4159…
Presymptomatic transmission is estimated to account for nearly half of the transmission burden.
nature.com/articles/s4159…
3/ The concern is that using PCR to detect asymptomatic exposures (through contact tracing programs) that subsequently return negative initially may give folks a false sense of security in the days leading up to symptom onset. To me, this is the most dangerous window.
4/ Because you think you’re fine; you are likely interacting with your family in close quarters without a mask on. And you very well could be transmitting virus without knowing it, as viral load is growing/peaking in the upper respiratory tract.
5/ The White House is trying to use the daily testing strategy to pick up possible cases. I think this reduces the chance that someone who is sick interacts w/ others, but certainly isn’t fool-proof. Strict quarantine is the only strategy that is.
nytimes.com/2020/05/10/us/…
nytimes.com/2020/05/10/us/…
6/ And this really means quarantine from the day of exposure...which is tough because you may not know the day you were exposed, especially if it was presymptomatic in nature.
Contact tracing efforts are in a race against the clock to reduce “exposure to quarantine” time.
Contact tracing efforts are in a race against the clock to reduce “exposure to quarantine” time.
7/ But they will need all the help they can get. I think both manual tracing + digital tracing will be important. Some models (see below) have gone as far as saying you can’t stop this epidemic without digital tracing.
science.sciencemag.org/content/368/64…
science.sciencemag.org/content/368/64…
8/ I’ve tweeted about this before- the South Korean digital tracing program, albeit invasive of personal privacy, is one to watch.
The screenshot paragraphs below really stuck out to me from this @NewYorker article.
newyorker.com/news/news-desk…
The screenshot paragraphs below really stuck out to me from this @NewYorker article.
newyorker.com/news/news-desk…
