Infect Minecraft villagers?

I'm just playing Minecraft again and have set up a functioning village with villagers. On YT I saw how someone improved the offerings of the NPCs by infecting them and then healing them again. I wanted to do that too, but instead of infecting the villager, he is simply killed. Do you have to pay attention to something or is it because I play the Bedrock Edition?

I think this is only a certain chance