More evidence a booster helps prevent you from catching Omicron. We knew that already from Pfizer but this study looks at risks within households, which is useful info as it provides an absolute rather than relative risk in a common situation
https://twitter.com/EricTopol/status/1476212140956553222
The chart ET posted is confusing, as it normalizes to the "fully vaxxed" state. Leaving aside the heterogeneity of this population (vaxxed at different times, and includes some unknown % with the less effective 1-shot J&J), normalizing to unvaxxed would be better. So I redid it. 
As you can see the relative protection from intra-household infection for a boosted person is 48% for Omicron and 84% for Delta vs unvaxxed. 48% is lower than the 70% Pfizer measured, but that's expected for the higher-exposure household setting compared to community transmission
ET doesn't clarify, and the abstract doesn't say, whether the transmission reduction by boosting is when the primary case or the secondary case is boosted. The table legend specifies it's the secondary case, i.e. boosters in the household members protect them from getting it.
Really wish authors would make it clear, when they say vaccines block transmission, if they mean getting infected or transmitting onward. This has been a source of confusion regarding the role of vaccines in blocking spread for a long time.
Finally, the new useful number here is the absolute risk of becoming positive. That's 30% within 7d for Omicron, 20% for Delta. Out of 2225, only 105 (<5%) were boosted. Nice chart.
BTW it shows, contrary to CDC, spread continues after day 5.
BTW it shows, contrary to CDC, spread continues after day 5.
You recall vaxxed unboosted are basically not protected against being infected by Omicron, so basically unvaxxed is ~30% likely to be infected by a household member within 7d, vaxxed unboosted is also ~30%, and boosted is ~15%.
So... if you don't want to get sick from your family member or roommate:
1. get boosted
2. avoid being in the same room when possible
3. wear a mask when in the same room when possible
1. get boosted
2. avoid being in the same room when possible
3. wear a mask when in the same room when possible
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