* Chronic Wasting Disease

Physical distancing may extend to 2022, COVID-19 study finds

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   researchers predicts that recurrent winter outbreaks will probably
   occur after the first, most severe pandemic wave; prolonged or
   intermittent physical distancing may be necessary into 2022; and a
   resurgence is possible as late as 2024.

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   Predicting the likely pattern of the pandemic is important in
   projecting the required intensity, duration, and urgency of contact
   tracing, lockdowns, and physical distancing in the absence of effective
   drug treatments and a vaccine.

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   So far, countries such as Singapore and Hong Kong have used intensive
   testing and case-based interventions to control COVID-19 outbreaks,
   while other countries are using physical distancing, closing schools
   and workplaces, and banning large gatherings.

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   a vaccine and therapies.

   China was able to slow the epidemic through social distancing, which
   the authors said would had to have reduced the baseline reproduction
   number (R nought [R[0]]) by at least 50% to 60%, assuming a baseline
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   re-emerges in 2024, they said.

Duration of distancing may hinge on seasonality

   To estimate how long physical (social) distancing measures need to be
   in place to slow COVID-19 transmission and how intense they need to be,
   the researchers used the SEIRS (susceptible, exposed, infectious,
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   requiring critical care (1.32%).

   They found that, although one-time physical distancing measures lowered
   the epidemic peak, infections resurged when they were lifted. And
   longer and stricter physical distancing didn't always correlate with
   greater peak flattening.

   For example, given 20 weeks of physical distancing achieving a 60%
   reduction in R[0 ]and no seasonal variation, the resurgence peak was
   nearly as high as the peak of the uncontrolled epidemic.

   "The social distancing was so effective that virtually no population
   immunity was built," the authors wrote. "The greatest reductions in
   peak size come from social distancing intensity and duration that
   divide cases approximately equally between peaks."

   But if seasonal variations occurred, simulations showed that the peak
   of a resurgence when physical distancing measures were lifted could be
   even higher than the one of an uncontrolled pandemic.

   "Strong social distancing maintained a high proportion of susceptible
   individuals in the population, leading to an intense epidemic
   when R[0] rises in the late autumn and winter," they said. "None of the
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   Increasing the capacity of the healthcare system to provide critical
   care would allow more people to become immune faster, shortening the
   need for physical distancing. Under that scenario, physical distancing
   could end by early- to mid-2021, and the pandemic could be over by July
   2022, according to the researchers.

   "Intermittent social distancing might maintain critical care demand
   within current thresholds, but widespread surveillance will be required
   to time the distancing measures correctly and avoid overshooting
   critical care capacity," they wrote.