COVID vaccine effects wane over time but still prevent death and severe illness. 16 Sep, 2021 | 10:10h | UTC COVID vaccine effects wane over time but still prevent death and severe illness – The Conversation Related: Perspective | What we actually know about waning immunity. Another study shows Pfizer mRNA vaccine immunity is reduced over time. [Press release – not published yet] Study shows vaccine protection wanes over time, but vaccines still offer good protection against severe disease. Studies: COVID vaccine protection waning against infection but not hospitalization. Pfizer says it’s time for a Covid booster; FDA and CDC say not so fast.