Bruine de Bruin, Wandi; Andrew M. Parker; Mirta Galesic and Raffaele Vardavas

Flu vaccinations are recommended for almost everyone, but uptake may vary due to perceived social norms. We aimed to examine the relationship between perceived social circle vaccine coverage (including family, friends, and acquaintances) and own vaccination behavior, as well as potential mediators. In 2011, 357 participants from RAND’s American Life Panel reported perceived social circle vaccine coverage for the 2010-11 flu season, own vaccination behavior for the 2009-10 and 2010-11 flu seasons, perceived flu risk without and with vaccination, and perceived vaccine safety. In 2012 and 2016, respectively, participants returned to report their own vaccination behavior for the 2011-12 flu season (N=338) and 2015-16 flu season (N=216). Perceiving greater percent of 2010-11 social circle vaccine coverage was associated with greater likelihood of getting vaccinated in the 2010-11 flu season (OR=1.03, 95% CI=1.01-1.04), and the subsequent 2011-12 flu season (OR=1.02, 95% CI=1.01-1.03), but not the 2015-16 flu season (OR=1.00, 95% CI=.99-1.01), as seen in logistic regressions that controlled for demographics and 2009-10 vaccination behavior. All significant relationships between social circle vaccine coverage and own vaccination behavior were mediated by perceived flu risk without vaccination. Perceived social circle vaccine coverage is associated with own vaccination behavior in the current and subsequent flu season, establishing behavior patterns that may persist into the future. People’s vaccination decisions may be informed by their perceptions of their peers’ beliefs and behaviors. We discuss intervention strategies for promoting vaccine uptake by counteracting negative and increasing positive perceived social norms. Keywords: influenza vaccination, risk perception, social sampling, social influences.