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It's notable that many countries in Europe now have similar stringency of control measures as Sweden (based on Oxford index). But there are a couple of important things to bear in mind... 1/
First, it doesn't mean countries would have seen same outcome if they'd used lighter measures throughout. Sweden had R=1 for much of spring ( https://epiforecasts.io/covid/posts/national/sweden/)– if other countries had kept R=1 rather than R<1, cases would have remained flat at higher level over time. 2/
Second, it doesn't mean we can get R=1 with no control in place. Sweden implemented multiple measures: high schools & universities closed, large gatherings were banned, bars employed social distancing, older groups were encouraged to stay home (more: https://www.folkhalsomyndigheten.se/the-public-health-agency-of-sweden/communicable-disease-control/covid-19/) 3/
Immunity may be having some effect (7% seroprevalence was reported in Stockholm in April – https://www.folkhalsomyndigheten.se/nyheter-och-press/nyhetsarkiv/2020/maj/forsta-resultaten-fran-pagaende-undersokning-av-antikroppar-for-covid-19-virus/) but only because other measures remain in place. If R=1 because of control measures, small amount of immunity can push R<1. But if R=3 with no control, it won't. 4/
Some have pointed to Sweden as evidence we can go back to normal. But data actually suggests the opposite - it illustrates stringency required to ensure R=1. If countries relax further than this & don't have other measures in place (e.g. TTI), they may well see rise in cases. 5/5
