A new research has discovered a gradual increase in the risk of Covid-19 infection from 90 days after receiving a second dose of the Pfizer-BioNTech vaccine. Results confirm that protection wanes with time and suggest a third (booster) dose might be warranted. The findings of the study were published in the journal 'BMJ'. The study was carried out by the Research Institute of Leumit Health Services in Israel. The findings confirm that the Pfizer-BioNTech vaccine provided excellent protection in the initial weeks after vaccination, but suggest that protection wanes for some individuals with time.