Regarding translating fold reductions of neutralization titers into vaccine effectiveness, I always go back to this: https://www.nature.com/articles/s41591-021-01377-8 (Fig 1a). Titers ~4x convalescent is what mRNAs do against wild-type, getting them to about 90%+ efficacy. About a 2x reduction against Delta means titers ~2x convalescent, getting them to about 85% efficacy. These conform with what we’ve seen. A 25-40x reduction against Omicron means titers .10-.16x convalescent, getting us down to 40% efficacy for two shots. Pfizer says a booster gets us back to “full” efficacy, and hopefully that holds up!
Regarding translating fold reductions of neutralization titers into vaccine effectiveness, I always go back to this: https://www.nature.com/articles/s41591-021-01377-8 (Fig 1a). Titers ~4x convalescent is what mRNAs do against wild-type, getting them to about 90%+ efficacy. About a 2x reduction against Delta means titers ~2x convalescent, getting them to about 85% efficacy. These conform with what we’ve seen. A 25-40x reduction against Omicron means titers .10-.16x convalescent, getting us down to 40% efficacy for two shots. Pfizer says a booster gets us back to “full” efficacy, and hopefully that holds up!