Ah, I get it I think. They mean that they fear the lambda variant could cause a bunch of reinfections in the formerly infected unvaccinated group?
Well, not necessarily reinfections, I think. Infections in general.
The issue is still the same: as of today, there's not a single country (I know of) where vaccination rates are high enough. So if you've got a variant that is going to spread more & faster, that also automatically means that more people are going to get sick.
Hence the lockdown talk to relieve pressure on hospitals.
Edit: am I the only one who thinks a certain someone in this thread has an annoying signature?