geoffrey modest medical blogs

  a recent large Canadian study confirmed that there were very few false positive results in rapid antigen tests for SARS-CoV-2 virus, and that the limited number of false positives were largely from manufacturing issues of the tests (see  covid false pos rapid antigen rare JAMA2022 in dropbox, or doi:10.1001/jama.2021.24355)   Details: -- Canada implemented their Creative Destruction Lab Rapid Screening Consortium (CDL RSC) in order to help protect against Covid transmission in workplaces     -- this program was set up to inform the operational requirements of rapid antigen screening in workplaces -- asymptomatic employees were screened twice weekly, on a voluntary basis -- data collected from January 11 to October 13, 2021 during which there were two significant Delta variant waves (March to June and August to October) -- screening results were recorded, including the place of employment, the test done, and (optionally) the lot number of the...

  The CDC just published an evaluation of the Abbott BinaxNOW rapid antigen test for SARS-CoV-2 infection at 2 community-based testing sites in Arizona (see  https://www.cdc.gov/mmwr/volumes/70/wr/mm7003e3.htm#T2_down  )   Details:  -- the BinaxNOW rapid antigen test received FDA Emergency Use Authorization      --it is advertised by Abbott as a "fast, $5, 15-minute, easy-to-use Covid-19 antigen test", and that with FDA EUA, is "ramping production to 50 million tests a month", and is the size of a credit card -- 3419 specimens were collected from people >10 yo, during November       -- age range 10-95yo, with median age 41, 7% age 10-17/55% aged 18-49/22% aged 50-64, and 16% >65yo      -- 38% male, 75% white/2% Black       -- asymptomatic 76%, symptomatic 24% with 19% having symptoms for <8 days: 11% 0-3 days, 8% 4-7 days  -- symptomatic people: 14% had a positive ...

  a recent mathematical modeling study suggested tweaking the current quarantine recommendations in the hopes of decreasing quarantine times by adding testing strategies, especially important with our current huge surge and more indoor exposure during  the upcoming holidays and prolonged winter,    (see  covid quarantine testing strategies medrxiv2020  in dropbox, or doi.org/10.1101/2020.10.27.20211631 )    Details:  -- the recommendation in general is to self-quarantine for 14 days after an exposure to someone who has Covid-19, per the CDC  -- the goal of this current mathematical modeling study is to blend the time of self-quarantine along with SARS-CoV-2 testing, to achieve optimal risk reduction for post quarantine transmission (PQT) of the virus  -- the current modeling assumes a one-day delay for testing results  -- they also assume that PCR specificity is 100% -- these models were based on clinical studies over time, fin...