Hi Mac, There are a few different issues with how you're interpreting those R0 numbers. The big one is that R0, the basic reproduction number <https://en.wikipedia.org/wiki/Basic_reproduction_number>, assumes an entirely "susceptible" population. That is, a population in which no one has any immunity, due to prior infection or vaccination. So your link is saying that if XBB.1.5 had suddenly appeared in 2019 each infected person would, on average, infect 5.4 other people. You're treating it as if it was Rt, the effective reproduction number <https://en.wikipedia.org/wiki/Basic_reproduction_number#Effective_reproduction_number>, but that's much lower, about 1 <https://covidestim.org/us/MA>.
Even then, you can't interpret Rt as how many other people you getting infected is likely to cause, even ignoring ways in which you're not average: the number of counterfactual infections can be much higher or lower: * In the early days of an epidemic that still has a good chance of successful suppression, the expected number of infections caused by a marginal case can be *far* larger than Rt. Each additional case makes it harder to suppress, and increases the chance that it spreads globally. * In a case where suppression is unlikely, the expected number of infections caused by a marginal case is lower than Rt. Each person you infect had some chance of otherwise being infected by someone else instead. Jeff On Sat, Apr 8, 2023 at 5:26 PM Walker Sloan via Organizers < organizers@lists.sharedweight.net> wrote: > > Becoming infected by Covid today is a lower risk to the individual than > at the start of the pandemic. > > However, becoming infected by Covid is also an opportunity for the Covid > virus to be transmitted to others, and to mutate. > > R0 is the number of people that an infected individual is likely to infect. > > R0 was 5.4 in Dec 2022. > > XBB.1.5 is estimated to be 82% of all Covid cases today. > > 5.4 and 82% are not numbers influenced by communities or individuals > attitudes towards risk. Only by community and individual behavior. > > People who assume increased risk for themselves are also assuming > increased risk for 5.4 other people. > > Masks, vaxes, and emails mitigate risks. > > These data are from an article published by a reputable university > hospital last month on Mar 17 2023. Scroll to the last page for R0. > > > https://www.ohsu.edu/sites/default/files/2023-03/Oregon-Hospital-Forecast-Trends-March17-2023.pdf > > Mac Sloan > _______________________________________________ > Organizers mailing list -- organizers@lists.sharedweight.net > To unsubscribe send an email to organizers-le...@lists.sharedweight.net >
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