Devi Sridhar+ Your Authors @devisridhar Professor & Chair of Global Public Health, @EdinburghUni Medical School. Director of @GlobalHealthGP. Health governance, financing, policy, systems & security. Jun. 09, 2020 1 min read + Your Authors

Confused why scientists disagree about a 'second wave'? Thread attempting to explain:
1. Definition of 'second wave' debated. Some think it's any increase in cases after a sustained drop over days. Others think it is an increase after prolonged period (months) of few cases.

2. Some think the virus will mutate to a milder or less infectious version (no evidence yet, just theory).

3. Others think there's been broad population exposure to this virus and/or there's cross-immunity from other viruses. They think antibody (serology) test estimates (5-6% of population have antibodies to #SARSCoV2) don't show role of T-cells, etc. (no evidence yet, just theory).

4. Others think a second wave can be avoided with aggressive containment (test/trace/isolate) & individual behaviours (handwashing/distancing) resulting in virus numbers becoming so low, transmission limited to discrete, containable outbreaks. (e.g.South Korea, Germany). My view.

5. Finally some think that regardless of what is attempted by governments, a second wave is inevitable. That ultimately this virus is unstoppable (like flu) until 60-80% of people is exposed. Hopefully some population immunity builds up & virus becomes endemic (herd immunity).

You can follow @devisridhar.


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