fleeing the virus https://www.theguardian.com/world/2020/mar/18/thank-you-parisians-dont-bring-the-virus-plea-from-rural-france
herd immunity in the UK https://www.washingtonpost.com/world/europe/uk-coronavirus-herd-immunity/2020/03/16/1c9d640e-66c7-11ea-b199-3a9799c54512_story.html
