There have been warnings from doctors and the UK’s Health Security Agency that waning immunity is leading to deaths even of people who have had two doses of a Covid vaccine. Research, which has not been formally published, estimates that the AstraZeneca vaccine reduced any form of Covid symptom by 66% shortly after the second dose. Five months later that figure had fallen to 47%. For Pfizer, the numbers fell from 90% to 70%. The greater risk of needing hospital care or even of dying is concentrated in the elderly. However, there is already evidence that the booster campaign - which has reached more than 11 million people in the UK - is making a difference. Data from the Office for National Statistics shows antibody levels - those first defenders against infection - have gone up again in the oldest age groups.  
Source : BBC