There's intensive community monitoring for flu. Flu's a big deal, which is why there are internationally coordinated programs to monitor which strains are circu

There's intensive community monitoring for flu. Flu's a big deal, which is why there are internationally coordinated programs to monitor which strains are circulating, and then to create and distribute vaccines. See this for an example of the work involved in the UK: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/526405/Flu_Annual_Report_2015_2016.pdf https://assets.publishing.service.gov.uk/government/uploads/...