Published: Sep 01, 2011 11:11 AM EDT

ELK GROVE VILLAGE, Ill. (AP) - The American Academy of Pediatrics has updated flu advice that says even children who got flu shots last year need to be vaccinated this season.
 
In recommendations released Thursday, the academy says the 2011-12 vaccine protects against the same three strains as last year.
 
That includes the H1N1 or swine flu strain that is expected to circulate again this year.
 
Immunity can drop several months after being vaccinated so new shots are recommended.
 
Flu vaccine is recommended for ages 6 months and up.
 
The academy says kids aged 9 and up need just one dose. Younger kids need just one dose if they got at least one last year. But younger kids need two doses at least a month apart if they weren't vaccinated last year.