> Neither reduced duration of infectiousness nor reduced quantity of shedding by definition protects the vulnerable. Everything which reduces community prevale

> Neither reduced duration of infectiousness nor reduced quantity of shedding by definition protects the vulnerable. Everything which reduces community prevalence (& case replication rates) protects the vulnerable, at least indirectly. Briefer and lesser shedding of infectious material is also likely to also contribute to milder cases among the unvaccinated - so they acquire natural-recovered immunity, both surface-mucosal and deep, over time with fewer risks to themselves & others. You are correct that simply having recently completed an initial vaccination should not give anyone confidence to immediately visit a vulnerable, unvaccinated person. After all, a surface/mucosal/sub-symptomatic infection that's still transmissible remains a possibility, especially while community infection rates are high. But 6-12 months later, when infection rates are low, and it's quite possible the vaccinated person has already been mucosally-challenged by naturally-circulating virus? At that point, the net effect of vaccines-over-time means the risk of such visits to the non-immune likely returns to the same baseline level that they had in 2018 and before, from everpresent pneumonia/flu concerns. > And we can also expect effectiveness (protection of the vaccine in the real world) to be lower than efficacy (reported from trials). It could go either way. Even in trials attempting blinding, often the vaccinated have a strong hunch (from side effects) they've received the active vaccine - and so take more risks than the placebo arm, thus causing the trial to underestimate actual protectiveness. Also, to the extent early vaccinations could be well-allocated to either most-vulnerable or most-likely-to-spread – subgroups that weren't overweighted in the trials – they could show more effectiveness in disease-prevention. And this only improves as herd immunity grows: in a tiny trial, others' vaccinations have little indirect protective effect, but as immunity rates rise in the community, there's a compounding benefit.