A study published in Vaccine examined influenza vaccine effectiveness for people with high-risk conditions.
Researchers gathered data from the U.S. Influenza Vaccine Effectiveness Network from 2012 to 2016. They compared vaccine effectiveness of standard-dose inactivated vaccines among patients 6 months or older with and without high-risk medical conditions. They collected data regarding presence of high-risk conditions and vaccination status from medical records.
Researchers found of 25,369 patients enrolled during four influenza seasons, 9,643 had high-risk conditions and 2,213 tested positive for the flu. For all ages, vaccine effectiveness against any flu type was lower among patients with high-risk conditions than those without.
For children younger than 18 years, vaccine effectiveness against any influenza was 51 percent among those with high-risk conditions and 52 percent among those without. For adults older than 18 years, vaccine effectiveness was 38 percent and 44 percent among those with and without high-risk conditions, respectively
"Influenza vaccination provided protection against medically attended influenza among patients with high-risk conditions, at levels approaching those observed among patients without high-risk conditions," study authors concluded.