The impact of a Facebook campaign among mothers on HPV vaccine uptake among their daughters: A randomized field study

Objective: The popularity of social networks provide an incredible opportunity to enhance the impact of preventive medicine programs. We aimed to assess whether a targeted Facebook campaign among mothers may increase the uptake of human Papilloma virus (HPV) immunization among their 8th-grade daughters. Methods: This field study was conducted among the members of a state-mandated health organization in Israel. Included were all 21,592 members who were mothers to 14 year-old daughters in the 2018-19 school-year. A total of 17,271 (80%) were randomly allocated to the campaign arm and the rest (n=4,321) were selected as a reference group. The Facebook ads addressed issues and concerns regarding HPV-related diseases and HPV vaccine. Main outcome measures were Facebook metrics on exposure to campaign and HPV immunization among eighth grade daughters of the study participants. Results: Between 8/2018-10/2018, Facebook ads were shown 1.8-million times (a reach of 88%). The uptake of HPV vaccine among daughters of women allocated to the campaign arm (55.3%) was similar (p = 0.749) to 55.0% in the control group. The only significant differences between study groups were observed when stratifying by SES level. In the lowest SES quartile, Facebook campaign significantly (p = .02) reduced vaccine uptake (35% vs. 39.0%), with a relative risk of 0.90 (95%CI: 0.82-0.98), while in the second SES quartile, Facebook campaign increased vaccine uptake from 52.6% to 55.8%, with a RR of 1.06 (95%CI,1.00-1.12). Among mothers in higher SES levels, daughters of exposed and unexposed mothers had similar immunization rates. Conclusions: Facebook campaign may increase the uptake of HPV vaccine among daughters to mothers of medium-to-low SES level, but it may reduce vaccination among lower SES groups.