I immunize to protect myself from diseases, because vaccines are scientifically tested and proven to be safe and save lives and are far safer than the diseases they prevent. I've had the flu once before - once is enough. It's not a bad cold. It kills. I've lost a friend to the flu. I also immunize to protect others, who cannot be immunized or who do not seroconvert, by contributing to the protective umbrella of herd immunity. I live in a community and a society, and I have an obligation to my fellow humans to act in ways that are supportive of the world we share.