“I wonder why you didn’t quote the very next sentence:
“Generally speaking, after about six months they become ineffective.””
Maybe cause it is not the very next sentence because it is not even in the report!
It’s the very next sentence in the article after the sentence you quoted:
“It is now recognized that their effectiveness quickly diminishes over time. Generally speaking, after about six months they become ineffective. It was found in this study that breakthrough infection rates 5-6 months post-vaccination are twice as high as 3-4 months post-vaccination....”