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1st APS COVID webinar today at noon ET!

  • 1.  1st APS COVID webinar today at noon ET!

    Topical Group Officer
    Posted 09-22-2020 23:47

    Please do not forget to join the 1st APS COVID webinar organized by CRRG today!
    If you haven't registered, you still can here or visit the APS COVID webinar webpage.

    Brief info about today's webinar:

    Webinar: Epidemiology of COVID-19: Implications for Control

    September 23, 2020
    12 Noon ET

    Speaker: Marc Lipsitch
    Moderator: Thomas Bortfeld

    Abstract: This talk will describe key features of the epidemiology of the COVID-19 pandemic with emphasis on the complexity of the data-generating mechanisms -- including delayed and incomplete reporting, local heterogeneity, and uncertain effectiveness of control measures -- and the challenges these pose for control. It will describe some approaches to addressing these challenges, including now-casting and detailed sensitivity analyses in models. It will conclude with a subjective view of some of the big open questions in the epidemiology of COVID-19.

    and future webinars:

    Upcoming Webinars

    What we know and don't know about SARS-CoV-2: physics of viruses
    Date: Oct 7 at noon ET
    Speaker: Raul Rabadan, Columbia University
    Moderator: Hossein Khiabanian, Rutgers University

    What we know and don't know about the role of droplets and aerosol in transmission of SARS-CoV-2
    Date: Oct 21 at noon ET
    Speaker: Adriaan Bax, NIH
    Moderator: Jose L. Jimenez, University of Colorado Boulder

    Immune interactions and SARS-CoV-2 evolution
    Date: Nov 4 at noon ET
    Speaker: Benjamin Greenbaum, MSKCC
    Moderator: Nicolas Vabret, Mt. Sinai

    Best regards,


    Robert Jeraj
    University of Wisconsin - Madison
    Madison WI

  • 2.  RE: 1st APS COVID webinar today at noon ET!

    Posted 09-25-2020 19:19
    I found this webinar very enlightening! I took some notes during Marc's presentation, which people might find useful (see below). There were many great points and interesting questions raised, some without good answers. If anyone has any thoughts, I would be interested in hearing what you all found most compelling from this talk, or what answers you might propose to some of the open questions. Thanks!

    • The data is terrible, measurements are conflicting, tools are ill-equipped, and thus the data is often not comparable across places and time
      • Data quality also hindered by unmeasured data points and changing delays
      • Delay distribution is not consistent over time
        • Showed plots which demonstrate that delay between symptom onset and diagnosis has been changing with each week since the pandemic started
    • Part of the solution = Nowcasting
      • Given how many cases we know about today and in recent past, how many cases will we eventually know about that occurred today and in the recent past?
      • Nowcast 'learns' the delay process
      • NYC department of health has been using a method of Nowcasting to fill in estimates of current cases
    • It is now clear that travelers initially spread the virus, often undetected
      • Rough linear relationship between number of cases and daily air travel volume
    • Spread has depended on:
      • Time of introduction (and some bad luck)
        • Branching process simulation
          • Large uncertainty in the inputs to the simulation
          • Initial studies found to not be able to narrow the uncertainty at all
            • BUT turned out we really needed to expand uncertainty and broaden hypotheses in order to best advice communities
          • Results of this work contributed to the urgency of the NYC response
      • Mobility
        • Mobility study with Facebook data examined counties in Mass, NY, Florida
          • Found heterogeneity of mobility across time between the states
      • Individual responses and risk factors
      • Seasonality (likely mild effect)
        • Compared to 2 common cold coronaviruses [Kissler et al. Science 2020]
          • ~20% reduction in summer from winter in these common colds
        • COVID-19 hasn't looked as seasonal because it has so many hosts to infect
          • Others have a depletion of hosts in summer months
      • A huge number of other possible factors
        • Prior exposures?
        • Demography?
        • Use of the BCG vaccine for TB?
        • T cell cross-immunity
      • Pre-symptomatic transmission is common
        • ~40% of transmission occurs prior to symptom onset (pre/asymptomatic)
          • Was a rough estimate but seems to have stood the test of time thus far
        • This is a challenge for contact tracing
          • Plot that shows strong evidence that individual quarantine is much more effective than just active monitoring, but that neither is really effective unless you have a large number of contacts traced (~75%) (Peak et al. 2020 Lancet Inf Diseases)
    • Contract tracing data from NYC
      • Only about ~25% of contacts are likely found (told about and able to be contacted), and usually already in the midst of their disease
      • It has worked well for other diseases, but it is likely only making a modest contribution to control in this case
    • Infection fatality rate: ~0.07% (not a constant!)
      • IFR increases dramatically with age
        • Log-linear increase up to ~10% between old and young
      • Age, race, and socio-economic status have been shown to have significant influence on IFR
    • Most of the world has experienced far less than 20% of population infected, already with catastrophic consequences in many places
    • Vaccines:
      • SEIR model
        • Susceptible, exposed, infected,
        • Age-stratified SEIR models allow us to ask more targeted questions
      • Lots of unknowns, but know that vaccine will be scarce
      • Modeled different prioritizations for vaccine distribution:
        • For mortality:
          • Vaccinating the oldest is the best strategy
          • Nearly imperturbable.. no matter the assumption, vaccinating the oldest is the most effective at reduction of deaths (robust across countries, etc)
        • For infections:
          • Vaccination the young adults is most effective (modest difference, can change order of best strategies using different assumptions)
      • Might be a benefit from pairing serology tests with a vaccination strategy
        • Test for antibodies (assuming these are effective) and only vaccinate seronegatives
    • Big open questions:
      • Where does transmission occur? How many activities can we do safely?
      • What are the predictors of superspreading and how can we prevent them>
      • Who is at risk for complications?
      • Will vaccines work at all? If so, for what outcome?

    Alison Deatsch
    Postdoctoral Research Associate
    University of Wisconsin - Madison
    Madison IL

  • 3.  RE: 1st APS COVID webinar today at noon ET!

    Posted 09-27-2020 03:47
    the webinar was great.  friends who didn't have a chance are asking where to go to see the recording.  is it available yet?  (i think you, Robert, said it would be.)  cheers.

    Greg Minshall
    Kadikoy, Istanbul

  • 4.  RE: 1st APS COVID webinar today at noon ET!

    Topical Group Officer
    Posted 09-27-2020 13:32
    Hi Greg,

    Thanks for asking and glad you liked the webinar (as we all did)!

    Yes, the recording of the webinar will be available in the CRRG library, likely early this week. The raw file is huge, so the APS team is transferring it into a more user-friendlier format. We are also considering posting all webinars on the APS YouTube Channel.

    Watch out for more information soon!


    Robert Jeraj
    University of Wisconsin - Madison
    Madison WI

  • 5.  RE: 1st APS COVID webinar today at noon ET!

    Topical Group Officer
    Posted 09-29-2020 12:26

    Recording of the 1st APS COVID webinar of Prof. Mark Lipsitch is now available at:

    It is also posted in the CRRG library.



    Robert Jeraj
    University of Wisconsin - Madison
    Madison WI