COVID-19: Boosters not only replenish immunity against transmission but lift it too, new data shows

These two types of protection - against transmission and against severe disease - are both very important, but they are also quite different. Just because a particular vaccine is good at one thing doesn't necessarily mean it's equally good at the other thing. Just because a particular vaccine's effectiveness at preventing transmission is waning doesn't necessarily mean its effectiveness at preventing serious disease is diminishing at the same rate. I say all of this not just because the two types of protection are often conflated (though they are) but because keeping this distinction under your hat is quite important when navigating all the data around COVID and vaccines.