Amandha Vollmer did an interesting video on this phenomena of the vaccine signals "transmitting" from person to person, as you and David Icke have mentioned. She hypothesized that some of the effect may be pheromone based, similar to how some women friends begin to sync their menstrual cycles when they hang out together a lot. In the vaccine case, though, it is a pheromone signal that may interrupt the reproductive system in other women.