Yes he said "sterilize"

I would like to draw your attention to the fact that Professor Sir John Bell, professor of medicine at Oxford University, and a part of the GAVI team developing AstraZeneca's coronavirus vaccine, said in an interview with Jon Snow that "These vaccines are unlikely to completely sterilize a population. They are very likely to have an effect which works in a %, say 60 or 70%." Believe him, someone who has these levels of credentials doesn't misspeak without correcting himself. - Steve Wills Sterilization: 1.The process of making something free from bacteria or other living microorganisms. "Microorganisms can be bacteria, fungi, archaea or protists. The term microorganisms does not include viruses and prions, which are generally classified as non-living."  

 [I'll also include the same video posted on youtube, but I expect that will get deleted soon.]