Which of the following statements is true regarding for influenza vaccine

Answer.D. Aquatic birds are reservoirs* RESERVOIR: Humans are the principle reservoir of human influenza A viruses. The an reservoir of influenza A viruses is wild birds, predominantly ducks, geese, and shorebirds.* Seasonal influenza tends to target children younger than 12 months of age and adults 65 years old or older.* Secondary attack rates were estimated at 10.3% (95% CI 6.8-14.7) for secondary cases with influenza-like illness and 20.2% (95% CI 15.4-25.6) for secondary cases with acute respiratory illness.