122 crew members leaving on fishing boat were screened for RNA and antibodies (Ab) 1-2d before departure. All tested negative for RNA but 6+ for Ab, w/ 3+ for neut Ab.
16d later 1 person got sick & boat returned. 103/117 tested positive on/after return for RNA or seroconverted.
16d later 1 person got sick & boat returned. 103/117 tested positive on/after return for RNA or seroconverted.
Paper & thread above focuses on N=2 of 3 people w/ neut Ab being PCR neg& 1 being weakly PCR pos (argued to be residual shedding, not infection) suggesting protection. Paper also mentions issues w/ Abbott test suggesting N=6 had Ab but their analysis indicates only 3 w/ neut Ab.
NYTimes @apoorva_nyc wrote a story on evidence for protective immunity & issues w/ Ab test w/ quotes from @florian_krammer @jbloom_lab:
nytimes.com/2020/08/19/hea…
nytimes.com/2020/08/19/hea…
But neither paper or article discuss fact that initial screening failed to find everyone that was infected. There are 2 options:
- 1+ person got infected b/w being tested & leaving 1-2d later
-Testing missed someone who was infected but viral loads were too low to be detected.
- 1+ person got infected b/w being tested & leaving 1-2d later
-Testing missed someone who was infected but viral loads were too low to be detected.
The 2nd possibility is something that I've been writing about for many months & still hasn't been addressed:
tl;dr A negative test does not rule out infection in asymptomatic people. We can't screen people once to find infected people.
tl;dr A negative test does not rule out infection in asymptomatic people. We can't screen people once to find infected people.
This issue is huge & impacts so many things: travel, schools, universities, visiting elder friends/family, employees returning to work. I worked w/ @sarahzhang on story about it for @TheAtlantic:
theatlantic.com/science/archiv…
theatlantic.com/science/archiv…
I also wrote about how it impacts travel to Hawaii & what they could do to improve on initial 1-test plan:
The latest development is UK trying to use testing to avoid 14d quarantine: forbes.com/sites/micheler…
They're using 2 tests "a few days" apart.
The latest development is UK trying to use testing to avoid 14d quarantine: forbes.com/sites/micheler…
They're using 2 tests "a few days" apart.
They say this will shorten quarantine from 14d to 5-8d. But at what cost? They will likely still miss an unknown fraction of infected people who are infected but don't have detectable virus by normal sampling. 1 case can turn into many very quickly (see NZ).
What can be done? As I detailed in thread (), need very simple study. Just repeated swabbing/testing of recent contacts of cases to determine when virus becomes detectable post-infection & compare this to 14d for 95% of people showing symptoms by 14d.
This would tell us whether testing can be used to shorten quarantine periods, or that there is no way to shorten them. Unfortunately, I don't know of any study that includes repeated sampling of contacts following the likely day of infection but it's not especially difficult.
In fact, I'd bet some form of this data already exists. But I don't think it's been published. If it has please share link here. This is extremely important!
Note: Daily testing w/ a cheap at-home test would be one way around this. @michaelmina_lab has been arguing for months for FDA to allow these tests.
