1. a person or thing that immunizes; especially, a vaccine or substance that produces immunity against disease
Usage: medical/scientific context
2. a person who administers immunizations or vaccines
Usage: medical professional

Examples

• The new immunizer was developed to protect against the flu virus.
• Healthcare workers serve as immunizers in vaccination clinics.
• This immunizer has been shown to be effective in clinical trials.
• The immunizer was administered to millions of people during the public health campaign.
• Doctors recommend this immunizer for children starting at age six months.
• The immunizer provides long-lasting protection against the disease.