Titres of antibodies drop in time. You can't expect this to last forever. Plus, vaccines are less effective against certain variants even at peak titres, so, wh

Titres of antibodies drop in time. You can't expect this to last forever. Plus, vaccines are less effective against certain variants even at peak titres, so, who knows how effective a vaccine administered today will be in the variants in circulation 6 months from now. Plus, mass vaccinations apply evolutionary pressure and although they slow the spread and thus the variability, they force only new variants or straints to spread, which could send us back to square one.