Which of the following individuals should not receive the annual influenza vaccine?

The annual influenza vaccine is typically recommended for a wide range of individuals, including young children, older adults, and pregnant women, as they are at higher risk for complications from influenza. However, the 5-month-old infant in this case should not receive the annual influenza vaccine, particularly if it is their first influenza vaccination year.

For infants younger than 6 months, the influenza vaccine is contraindicated. The immune systems of very young infants are still developing, and they are at a greater risk of experiencing adverse effects from vaccines if their immune response is not robust enough. The first influenza vaccination is usually recommended around 6 months of age to ensure that the infant has had adequate time to develop an immune response after birth.

In contrast, the other individuals mentioned—such as the 65-year-old male, the 20-year-old female, and the 45-year-old pregnant woman—are all eligible for the influenza vaccine, as they would benefit from the protection it offers against influenza and its complications.