Flu vaccine estimated to be 21% effective against flu spread to household members
University of Minnesota http://twin-cities.umn.edu/ 612-625-5000 A study of 700 people who tested positive for influenza suggests that their risk of infecting household contacts was 18.8% and that the estimated effectiveness of flu vaccines against secondary infections is 21.0%. Vanderbilt University–led researchers tested nasal swabs for evidence of influenza and analyzed symptom diaries for up to 7 days from 699 participants and their 1,581 household members during the 2017-18, 2018-19, and 2019-20
