My biggest fear is immunity of an individual lasts around 6 month.Thats why we are looking at wave after wave in different countries approximately 6 months apart. Data from Israel is scary and kind of points to similar trend.
Are you talking about the data from Israel that shows efficacy of the Pfizer vaccine dropping to 67.5%?
If so what you are seeing is Simpson's paradox. The same data when broken down by under 50 and 50+ gives 91.8% and 85.2%. Breaking it down even farther by age group gives:
