> As far as I’m aware, research shows that a two-dose vaccination rate provides disappointing reductions in transmissiveness - but far, far better than nothing.
The paper you quote shows two-dose vaccination (or previous infection) increasing the secondary attack rate from 29% (unvaccinated) to 32%, i.e. worse than nothing. Only a booster reduces it back to 25%.
My guess is that the increase is not due to direct biochemical effects of vaccination/prior infection, but due to people assuming that they're protected and taking fewer precautions. Demographic differences might also play a role.
> After adjustment for confounders, we found that in households with the Delta VOC, the OR of infection was 2.31 (95% confidence interval (CI) 2.09-2.55) for unvaccinated individuals and 0.38 (CI: 0.32-0.46) for booster-vaccinated individuals when compared to fully vaccinated potential secondary cases. For households with the Omicron VOC, the corresponding OR for infection for unvaccinated individuals was 1.04 (CI: 0.87-1.24) and 0.54 (CI: 0.40-0.71) for booster-vaccinated individuals.
For delta, two dose vaccination helps. For Omicron, there is no statistically significant effect of two dose vaccination.
In no case is there an increase from two dose vaccination of attack rates.
The paper you quote shows two-dose vaccination (or previous infection) increasing the secondary attack rate from 29% (unvaccinated) to 32%, i.e. worse than nothing. Only a booster reduces it back to 25%.
My guess is that the increase is not due to direct biochemical effects of vaccination/prior infection, but due to people assuming that they're protected and taking fewer precautions. Demographic differences might also play a role.