Thank you @Carla!
I heard that HLC members received a letter last year about the biological contents of vaccines (aborted tissues etc.) and they are instructed to respond in a specific way in case a Witness comes asking them. If no one asks, they will not mention it. If asked, they will not deny but will reply in such a way that it is up to the Witness to do research and decide. This can be cross-checked easily with an HLC member near you.
WT, by only mentioning whether a vaccine contains blood fractions or not, is misleading witnesses, knowing that none of them will make their own research. If they were transparent, they would openly talk about the ingredients of vaccines and many witnesses would be well informed and would make an informed decision.